Finally (!) after a two year wait, my building received hookup of the
second leg of an electrical service upgrade (delay was due to asbestos
contamination issues)...I now have 220VAC availible. Time to hookup my
5HP/80 gallon IR compressor!
I have a question regarding grounding that I need to be clear on
before proceeding.
*[I have copy of the NEC 2002 Codebook in case anyone needs to
reference it].
Here's the hardware configuration:
-Compressor Motor: 5HP/230VAC/ 1 Phase/ 22.5 FLA
-Electrical Service Panel:
We have BX metal cable in this building which is the local NYC code.
The breaker panel in my place has as the main feed a metal Greenfield
conduit entering it: the Greenfield carries three wires,
white/red/blk. There is NO green ground wire anywhere in this panel.
Red connects to one side of the breaker terminal. Black connects to
the other side of the breaker terminal. White goes to a seperate
non-breaker terminal, and I am assuming the white is thus neutral.
Here are the voltage meter readings I get when testing at the breaker
panel:
Blk/Red =209VAC
Blk/Wht =120VAC
Red/Wht =120VAC
Wht/Service Panel = 0.29 VAC
Blk/ Service Panel = 120VAC
Red/ Service Panel = 120VAC
------------------------
I intend to run BX cable from the service panel to an enclosed metal
switchbox: and then a short length of Liquid Tite Flexible Metal
Conduit from the switchbox to the compressor motor. I am using 10guage
wire for the circuit. Total length of the circuit from panel to motor
is approx. 20'.
Questions:
1) Will a 230VAC single phase motor run OK on 210VAC service?
2) I need either a Duplex Breaker, or 2 Single Breakers to control the
circuit. What should each pole of the breaker be rated at? Is 25 or
30amps
correct? Do I need any special 'motor type breaker'?
3)The motor has terminals for 2 wires and 1 ground wire. From my
understanding I can run the Red (120VAC) & Blk (120VAC) from the
breaker panel to the switchbox, and then from the switchbox onto the
motor to their respective terminals. However, what do I use as a
ground wire???
Can I put a copper grounding screw/lug into the service panel box and
run a green ground wire off of that and use it as my ground?
4) There is no need to utilize the white wire in this circuit, correct
(unless I decide to place a 120VAC outlet somewhere on the circuit?
Thanks a bunch.
-N.
I have the current NEC codebook but am still perplexed.
Thanks for any clarification.
Somebody wrote:
> According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor
with
> a motor designed for 230v AC on a 208v circuit. IR sells a special 208v
> motor for those installations. You have to order it with the correct motor
> on it.
Absolutely true.
If you want to operate a 230V motor on a 208V supply, you must add a
buck-boost transformer to the system.
By definition, a motor must be able to operate at +/-10% of nameplate
voltage.
For a 230V motor, that translates to 207V minimum which sounds like it might
work on a 208V supply; however, the utility supply voltage is allowed to
operate at +/-10% which translates into 187V minimum.
Therein lies the rub. You can't get there from here.
Add a buck-boost x'fmr.
They are small and relatively low cost.
HTH
--
Lew
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: <http://home.earthlink.net/~lewhodgett> for Pictures
Doug Miller wrote:
> In article <[email protected]>, -n.
> <[email protected]> wrote: [snip]
>>
>> UPDATE:
>> I spoke by phone with the electrical contractor who did the install
>> and asked him exactly what kind of service I now have. He responded
>> that I have two lines at 115VAC with a common nuetral. It is single
>> phase 208VAC service.
>
> This is extremely doubtful. 208V is THREE-phase, not single-phase.
> You might have two legs of a three-phase service. What voltage do you
> measure between the two 115V legs?
He said 210 in a previous post.
>
>> He
>> mentioned that for 230VAC motor, I should do the install for a
>> 220VAC line, with double breaker.
>> I asked his opinion about running a 230 VAC 1-phase motor on 208
>> service...he said it wouldn't be a problem, at the very worst the
>> motor may run a little slow.
>
> You need to get a _competent_ electrician, ASAP. This guy doesn't
> have a clue. Unless the motor was designed to be run on 208 3-phase,
> you'll burn it up in a hurry.
His "electrician" is definitely clueless. There are plenty of 208/230 single
phase motors however. Otherwise the vast number of commercial and
institutional customers with 208Y service would not be able to use them.
On Tue, 2 Dec 2003 18:08:53 -0400, Scott Lurndal wrote
(in message <[email protected]>):
> Roger Hull <[email protected]> writes:
>> On Tue, 2 Dec 2003 10:10:12 -0800, N. wrote
>
>>> Questions:
>>> 1) Will a 230VAC single phase motor run OK on 210VAC service?
>>> 2) I need either a Duplex Breaker, or 2 Single Breakers to control the
>>> circuit. What should each pole of the breaker be rated at? Is 25 or
>>> 30amps
>>> correct? Do I need any special 'motor type breaker'?
>>> 3)The motor has terminals for 2 wires and 1 ground wire. From my
>>> understanding I can run the Red (120VAC) & Blk (120VAC) from the
>>> breaker panel to the switchbox, and then from the switchbox onto the
>>> motor to their respective terminals. However, what do I use as a
>>> ground wire???
>>> Can I put a copper grounding screw/lug into the service panel box and
>>> run a green ground wire off of that and use it as my ground?
>>> 4) There is no need to utilize the white wire in this circuit, correct
>>> (unless I decide to place a 120VAC outlet somewhere on the circuit?
>>>
>>> Thanks a bunch.
>>> -N.
>>>
>>>
>>> I have the current NEC codebook but am still perplexed.
>>> Thanks for any clarification.
>>
>> I have no knowledge of NYC local codes, but as far as the national code
>> goes:
>>
>> 1. Yes
>> 2. A double breaker is required. 30 Amp would be correct for #10 wire.
>> 3. The ground is through the shell of the BX cable. If your flex does not
>> complete the grounding path a bonding wire must be installed.
>> A copper lug in the panel is not necessary, I am unclear as to if the
>> panel
>> is your "Service entrance" or a subpanel. If a subpanel a lug is NOT
>> allowed.
>
> Not quite. If it is a subpanel, bonding the grounded conductor and the
> grounding conductor is not allowed. It is common for a subpanel to have
> a ground bar bonded to the panel (the panel is required to be bonded
> to the grounding conductor, but that happens through the BX shell as
> pointed out in this case).
>
> The NEC no longer allows the armor on some armored cables to be used
> as the grounding conductor. This typically applies to flexible metal
> conduit, but may also apply to BX armored cable. Check the book.
>
>> 4. Correct.
>>
>
> scott
Regarding service panels: The basement houses the 'Main Service Feed Panel'
for the building. I live on the 4th floor, and I have a 'Breaker Panel' that
is fed from that main panel: a Greenfield cable rises 4 floors and enters my
'Breaker Panel'...it is the ONLY panel in my living space. Nomenclature: does
this 'Breaker Panel' generally qualify as a 'subpanel', or conversely, would
a 'subpanel' be the nomenclature for any additional breaker panel installed
along a new circuit I run downstream from my 'Breaker Panel'?
Yes, I had assumed the ground to be the shell of the BX cable...there is no
'ground bar' in my breaker panel.
In my space, none of the receptacles have a ground wire .... I assume the BX
cable itself to be the ground.
Regarding grounding the motor to the 'Breaker Panel': I was thinking the
BX/Flexible Metal Conduit would suffice, but I had purchased a little copper
screw/terminal to screw to the 'Breaker Panel" (refering to it as a 'lug' in
my initial post). I'm still a little unclear as to general grounding/bonding
practices, and was wondering if the BX was sufficient for the ground in my
circuit, or if I would need to install a seperate green ground wire off the
'lug' from the 'Breaker Panel' and connect that to the motor.
When the electrical upgrade was made, the contractor installed a new
receptacle and ran BX back to the 'Breaker Panel"...there is no seperate
ground wire in this circuit, so, yes, I'm assuming the BX is functioning as
the ground.
What are the views on the best way for me to execute the ground for this
motor circuit?
Thanks again.
-N.
--
Swap out the air for lovegasoline to make contact.
On Tue, 2 Dec 2003 22:16:38 -0400, ATP wrote
(in message <[email protected]>):
> BX is a lot different than Flexible Metal Conduit. Run the separate ground.
> When you install the lug in the subpanel scrape the paint off the back of
> the subpanel behind the lug.
Good idea.
Thanks to all for the assistance.
I have one last question.
As long as I'm running the circuit into the room the compressor is in, I
figure I might as well throw in an additional 120VAC recep while I'm at it.
This would be for running other shop stuff, likely when the compressor ISN'T
running.
What would be the simplest method?
Can I branch off one of the 120VAC wires going to the compressor (either the
red or black) either before or after it enters the compressor's switchbox,
and then run it down to a standard dual 120VAC three prong wall receptacle
Of course I would have to run a white neutral wire off the subpanel to
complete the wiring to the recep.
I could always just run a completely seperate 120VAC wire and a white nuetral
wire from the subpanel and put them on a dedicated breaker to provide juice
to the recep. I just figure it would be easier to run both the 120VAC recep
and the compressor motor off the same circuit.
Is that kosher?
Thanks.
-N.
On Tue, 2 Dec 2003 16:56:23 -0400, Roger Hull wrote
(in message <[email protected]>):
> Roger in Vegas
> Worlds Greatest Impulse Buyer
Roger, what sort of purchases are we talking about to have won the title?
-N.
On Sat, 13 Dec 2003 1:22:28 -0400, Checkmate wrote
(in message <[email protected]>):
>
> Most likely they're feeding the building with three phase, but splitting
> it up to the individual apartments with approximately 1/3 of the units
> on AB, BC, and CA. That's pretty unusual in residential buildings. Too
> bad he can't pull the third leg up to his unit, but he's most likely on
> a single phase meter unless there's just one meter for everybody.
>
>
>> Anyway -- if you are measuring 120V from neutral to both hots,
>> but 209 between them, you *are* getting two phases of a 208V three phase
>> feed.
>>
>>> I don't think that reset button will protect you from chronic
>>> undervoltage.
>>> How big a motor is this? If it's just a horse or two, then your solution
>>> is
>>> really simple - buy a cheap buck/boost transformer, hook it up, and have a
>>> nice cup of coffee!
>
Yes, it is an apatment building...thanks, I now understand why (2 legs of a)
3-phase service registers 208VAC. The motor is 5hp nominal,an Emerson motor,
rated @ 22FLA.
What spec Buck-boost transformer should I be shopping for?
Any good online sources for the above?
Thanks again guys for the electricity lesson.
On Tue, 2 Dec 2003 10:10:12 -0800, N. wrote
(in message <[email protected]>):
> Finally (!) after a two year wait, my building received hookup of the
> second leg of an electrical service upgrade (delay was due to asbestos
> contamination issues)...I now have 220VAC availible. Time to hookup my
> 5HP/80 gallon IR compressor!
>
> I have a question regarding grounding that I need to be clear on
> before proceeding.
> *[I have copy of the NEC 2002 Codebook in case anyone needs to
> reference it].
>
> Here's the hardware configuration:
> -Compressor Motor: 5HP/230VAC/ 1 Phase/ 22.5 FLA
> -Electrical Service Panel:
> We have BX metal cable in this building which is the local NYC code.
> The breaker panel in my place has as the main feed a metal Greenfield
> conduit entering it: the Greenfield carries three wires,
> white/red/blk. There is NO green ground wire anywhere in this panel.
> Red connects to one side of the breaker terminal. Black connects to
> the other side of the breaker terminal. White goes to a seperate
> non-breaker terminal, and I am assuming the white is thus neutral.
>
> Here are the voltage meter readings I get when testing at the breaker
> panel:
> Blk/Red =209VAC
> Blk/Wht =120VAC
> Red/Wht =120VAC
> Wht/Service Panel = 0.29 VAC
> Blk/ Service Panel = 120VAC
> Red/ Service Panel = 120VAC
>
> ------------------------
> I intend to run BX cable from the service panel to an enclosed metal
> switchbox: and then a short length of Liquid Tite Flexible Metal
> Conduit from the switchbox to the compressor motor. I am using 10guage
> wire for the circuit. Total length of the circuit from panel to motor
> is approx. 20'.
>
> Questions:
> 1) Will a 230VAC single phase motor run OK on 210VAC service?
> 2) I need either a Duplex Breaker, or 2 Single Breakers to control the
> circuit. What should each pole of the breaker be rated at? Is 25 or
> 30amps
> correct? Do I need any special 'motor type breaker'?
> 3)The motor has terminals for 2 wires and 1 ground wire. From my
> understanding I can run the Red (120VAC) & Blk (120VAC) from the
> breaker panel to the switchbox, and then from the switchbox onto the
> motor to their respective terminals. However, what do I use as a
> ground wire???
> Can I put a copper grounding screw/lug into the service panel box and
> run a green ground wire off of that and use it as my ground?
> 4) There is no need to utilize the white wire in this circuit, correct
> (unless I decide to place a 120VAC outlet somewhere on the circuit?
>
> Thanks a bunch.
> -N.
>
>
> I have the current NEC codebook but am still perplexed.
> Thanks for any clarification.
I have no knowledge of NYC local codes, but as far as the national code goes:
1. Yes
2. A double breaker is required. 30 Amp would be correct for #10 wire.
3. The ground is through the shell of the BX cable. If your flex does not
complete the grounding path a bonding wire must be installed.
A copper lug in the panel is not necessary, I am unclear as to if the panel
is your "Service entrance" or a subpanel. If a subpanel a lug is NOT allowed.
4. Correct.
Roger in Vegas
Worlds Greatest Impulse Buyer
Any breaker panel that is fed from another breaker panel is a subpanel.
There is only one "Service entrance" panel and it is fed from the power
company lines. The panel in your living quarters sounds like a subpanel and
is fed from the service entrance somewhere else in the building.
As to running an additional green wire from the motor to the panel, it is not
necessary by code but will do no harm (Except to confuse the next occupant :)
On Wed, 3 Dec 2003 1:27:37 -0500, Anthony wrote
(in message <[email protected]>):
> If the panel you refer to is your service entrance, you *SHOULD* have a
> bare #6 min/#4 preferred BARE ground wire running from the terminal block
> which the white wire connects to a ground rod outside your building. This
> provides the earth ground. As for your installation:
> Typically, you will use a double breaker, 30A for #10 wire.
> Pull 3 wires, 1 red, 1 black and 1 bare from your panel to the disconnect
> box, and the same to your compressor.
> Red to one hot side, black to the other and ground to the ground lug on
> the compressor.
> The ground must also attach via screw, to the disconnect box (if using
> metal box) This bare ground should connect to the neutral/ground terminal
> strip in the service panel.
The breaker panel in my residence does have a terminal block that the white
nuetral wire connects to (the largest white wire that comes from the main
service panel in the building's basement), and is also where all the white
neutral wires for the various circuits in my residence also terminate (but no
bare wires connect to it...indeed, there are no bare wires in my breaker
panel). Are you suggesting that this terminal block is where I should connect
the bare ground wire to (instead of just connecting to the panel itself)?
> In combination with the ground rod/#6/4 wire this provides a direct earth
> ground for the compressor.
>
Thanks.
-N.
On Wed, 3 Dec 2003 23:40:33 -0500, ATP wrote
(in message <[email protected]>):
> Lew Hodgett wrote:
>> RE: Subject
>>
>> Some where in this thread, 209V was noted as a measured voltage.
>>
>> If that data is in fact true, you may be getting two legs and a
>> neutral of a 208Y/120V, 3 phase service.
>>
>> If that is true, you will almost certainly burn up a 240V motor
>> unless you also install a buck-boost transformer for the 240V motor.
>>
>> BTW, 208Y/120V is quite common in commercial buildings.
>>
>> Be a good idea to reconfirm your supply voltage.
>
> Although 208/230 motors are pretty common, he should check the nameplate.
>
UPDATE:
I spoke by phone with the electrical contractor who did the install and asked
him exactly what kind of service I now have. He responded that I have two
lines at 115VAC with a common nuetral. It is single phase 208VAC service. He
mentioned that for 230VAC motor, I should do the install for a 220VAC line,
with double breaker.
I asked his opinion about running a 230 VAC 1-phase motor on 208 service...he
said it wouldn't be a problem, at the very worst the motor may run a little
slow.
-N.
On Sat, 6 Dec 2003 14:37:52 -0500, Checkmate wrote
(in message <[email protected]>):
>
> On Sat, 6 Dec 2003 08:24:57 -0600, Rick put forth the notion that...
>
>> According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor
>> with
>> a motor designed for 230v AC on a 208v circuit. IR sells a special 208v
>> motor for those installations. You have to order it with the correct motor
>> on it.
>>
>> We've tried using the standard 230v motor and had problems with them
>> overheating and shorting out. It will run for a while, but eventually the
>> motor will fail.
>>
>> We are seeing more and more 208v in our area instead of 230v. I'm not sure
>> of the reason, but most newly constructed areas are being serviced with
>> 208v.
>>
>> Rick
>
> It's a simple matter to get a 240/24 volt transformer, and wire it up in
> a boost configuration. This will turn 208 volts into 230.
Checkmate, can you elaborate on this boost transformer setup? Also, any idea
what the equipment would cost (new or surplus) to gt it done?
Thanks,
-N.
On Sat, 6 Dec 2003 10:24:57 -0500, Rick wrote
(in message <[email protected]>):
> According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor with
> a motor designed for 230v AC on a 208v circuit. IR sells a special 208v
> motor for those installations. You have to order it with the correct motor
> on it.
>
> We've tried using the standard 230v motor and had problems with them
> overheating and shorting out. It will run for a while, but eventually the
> motor will fail.
>
> We are seeing more and more 208v in our area instead of 230v. I'm not sure
> of the reason, but most newly constructed areas are being serviced with
> 208v.
Rick,
That is not news I want to hear.
This goes for running 230VAC single phase on 208VAC single phase service?
I had always thought there was some lattitude in voltage ratings of motors.
Can anyone elaborate on why this would cause overheatng/shorting? Trying to
learn something along the way.
-N.
On Sat, 6 Dec 2003 15:12:08 -0500, Mike wrote
(in message <[email protected]>):
> -n. <[email protected]> wrote
>> Good idea.
>> Thanks to all for the assistance.
>>
>> I have one last question.
>
> You are nuts to get your electrical wiring information from this
> group. In the past some of the information I've seen posted is
> downright dangerous, a lot is just plain wrong, some misguided, some
> pertains to other jurisdictions or situations or is out of date, some
> makes no economic sense. A small part is good sound advice from
> knowledgable professionals who are up on current code. So how do you
> sort it out? Hire an electrician.
>
> mike
Mike,
I appreciate your admonition: with enough input I think the resolution(s)
rise to the top of the heap eventually. It may take a little debate to get
there, but often a few heads are better than one, and there are many
knowledgeble folks on these newsgroups. In fact, a few years ago when I was
first exploring electronics and wanted to design a digitalyl controlled
circuit, an electrical engineer emailed me and it started a very intense
email education...the man is brilliant and knew his stuff....one of the
greatest learning experiences of my life.
What you say can be true, but there are also some smart, informed , and
experienced folks on here. I'll wait till I get the doubts ironed out and
get consensus, then go forward.
Cheers,
-N.
On Wed, 3 Dec 2003 11:27:06 -0500, Anthony wrote
(in message <[email protected]>):
> -n. <[email protected]> wrote in
> news:[email protected]:
>
>> On Wed, 3 Dec 2003 1:27:37 -0500, Anthony wrote
>> (in message <[email protected]>):
>>> As for your installation:
>>> Typically, you will use a double breaker, 30A for #10 wire.
>>> Pull 3 wires, 1 red, 1 black and 1 bare from your panel to the
>>> disconnect box, and the same to your compressor.
>>> Red to one hot side, black to the other and ground to the ground lug
>>> on the compressor.
>>> The ground must also attach via screw, to the disconnect box (if
>>> using metal box) This bare ground should connect to the
>>> neutral/ground terminal strip in the service panel.
To reiterate:
I am clear on this above wiring scheme except for one detail. The panel I am
starting from is a subpanel and it does not contain any grounding bar or
grounding terminal. In this case, does my ground wire need to be bare, or
will green insulated work just as well?
I pull red, black, and green insulated ground (all 10awg). Red goes to one
pole of 30A dual breaker, black goes to other pole of breaker, for ground I
drill a hole into the subpanel box itself then scrape some paint away and
screw in a copper grounding lug. I run these three wires through BX cable to
a 30AMP rated disconnect box, making certain to affix the ground to the
disconnect box via a screw and to acheive good continuity. THese 3 wires exit
the disconnect box and are encased in liquid tite flexible metal conduit
which goes to the compressor motor/switch. Again, black and red connect to
respective lugs on the motor and the ground goes to ground lug on motor.
[If I find out a boost transformer is absolutely needed to boost my 208VAC
service to run the 230VAC motor, I will research that and add it t the
system].
If I wish to install a 120VAC recep box in the same room as the compressor,
it must be on a seperate ciruit with a dedicated breaker, NOT off the hot
wires used in the compressor circuit.
The only other modification I can forsee doing to this compressor circuit
would be to install a 230VAC receptacle in the wall and a mating 230VAC
plug/cordset [10awg, 3 wire: red, black, green] on the compressor .... and
run that downstream from the disconnect box as an option instead of the
hardwired liquid tite flexible metal conduit.
What do you think guys, does that sound like it confirms to code?
Thanks.
-N.
>> The breaker panel in my residence does have a terminal block that the
>> white nuetral wire connects to (the largest white wire that comes from
>> the main service panel in the building's basement), and is also where
>> all the white neutral wires for the various circuits in my residence
>> also terminate (but no bare wires connect to it...indeed, there are no
>> bare wires in my breaker panel). Are you suggesting that this terminal
>> block is where I should connect the bare ground wire to (instead of
>> just connecting to the panel itself)?
>>
>>
>>> In combination with the ground rod/#6/4 wire this provides a direct
>>> earth ground for the compressor.
>>>
>>
>> Thanks.
>> -N.
>>
>>
>
> Obviously this system is grounded through the conduit (not my preference,
> but ok)
> In this case, the metal flex conduit from the breaker panel to the
> disconnect box obviously serves as ground path. You will probably need a
> bonding wire (bare or green) from the ground lug on the compressor to the
> ground lug on the disconnect box (the actual box itself).
>
>
>
>
On Thu, 11 Dec 2003 11:58:40 -0500, Checkmate wrote
(in message <[email protected]>):
>
>
>> I asked his opinion about running a 230 VAC 1-phase motor on 208
>> service...he
>> said it wouldn't be a problem, at the very worst the motor may run a
>> little
>> slow.
>
> What he should have said, is at the worst it may run a little HOT. AC
> induction motors turn at a certain speed because of the frequency of the
> sine wave, not the amount of voltage. If you give the motor less
> voltage than it was designed for, it won't slow down initially, it'll
> draw more current, and current equals heat. You really have to lower
> the voltage significantly to see a drop in speed, but you don't have to
> lower it a whole lot to see an increase in amperage and heat buildup.
> Some motors are designed to run on anything between 208 and 230, but not
> all of them. If the manufacturer says the motor is okay to run at 208,
> that's fine, but don't go by what the contractor is telling you.
>
To reiterate, the supply voltage I measured is 209VAC between the two hots.
The motor states 230VAC single phase, 1.25 service factor, and is thermally
proteted with a reset button.
Again, the electrical contractor who owns the bizz that did the install
states I have single phase service @ 208VAC....although many of you are
claiming that this latter data must be incorrect. I will need to bug that
contractor again and discuss the doubts expressed here.
I haven't spoken with the motor manufacturer to check if the motor can run
on 208-230VAC, although it most certainly does not list 208-230VAC on the
nameplate.
Is there a way for me to check and confirm the phase of the service I have (1
or 3 phase) with only a voltage/amp meter?
Lastly, going with only the data I now have, many of you have expressed
concern that the motor would run HOT and possibly burn out, short, or
experience a reduced servie life if it were connected as is without a boost
transformer. Hypothetically, wouldn't the thermal protection/reset circuit in
the motor protect it before damage was done by shutting off the motor in the
event that it did experience an increase in temp?
Thanks again.
ATP wrote:
>
> -n. wrote:
> > ...
> > Can I branch off one of the 120VAC wires going to the compressor
> ...
>
> No. You could accomplish the same thing by running a small feeder to a
> subpanel, but you cannot piggyback a receptacle load on a hot leg running to
> a piece of equipment. ...
Especially because the wires going to the compressor will be protected
by a 25 or 30 amp breaker. You want the 120 receptacle to be on a 15 or
20 amp breaker.
Rick wrote:
> We are seeing more and more 208v in our area instead of 230v. I'm not sure
> of the reason, but most newly constructed areas are being serviced with
> 208v.
Most new areas are seeing three phase power distribution. Single phase
service is provided by tapping off one phase and neutral. The result is
208V.
Ted
Checkmate wrote:
>
> On Sat, 06 Dec 2003 20:51:50 GMT, Ted Edwards put forth the notion
> that...
>
> > Rick wrote:
> >
> > > We are seeing more and more 208v in our area instead of 230v. I'm not sure
> > > of the reason, but most newly constructed areas are being serviced with
> > > 208v.
> >
> > Most new areas are seeing three phase power distribution. Single phase
> > service is provided by tapping off one phase and neutral. The result is
> > 208V.
> >
> > Ted
>
> One phase and neutral gives you 120 volts.
Your right. Sorry. Neutral to any phase is 120. As a result, from one
phase to another is 208 volts.
Ted
Lew Hodgett wrote:
> RE: Subject
>
> Some where in this thread, 209V was noted as a measured voltage.
>
> If that data is in fact true, you may be getting two legs and a
> neutral of a 208Y/120V, 3 phase service.
>
> If that is true, you will almost certainly burn up a 240V motor
> unless you also install a buck-boost transformer for the 240V motor.
>
> BTW, 208Y/120V is quite common in commercial buildings.
>
> Be a good idea to reconfirm your supply voltage.
Although 208/230 motors are pretty common, he should check the nameplate.
-n. wrote:
> On Tue, 2 Dec 2003 22:16:38 -0400, ATP wrote
> (in message <[email protected]>):
>
>> BX is a lot different than Flexible Metal Conduit. Run the separate
>> ground. When you install the lug in the subpanel scrape the paint
>> off the back of the subpanel behind the lug.
>
> Good idea.
> Thanks to all for the assistance.
>
> I have one last question.
> As long as I'm running the circuit into the room the compressor is
> in, I figure I might as well throw in an additional 120VAC recep
> while I'm at it. This would be for running other shop stuff, likely
> when the compressor ISN'T running.
> What would be the simplest method?
> Can I branch off one of the 120VAC wires going to the compressor
> (either the red or black) either before or after it enters the
> compressor's switchbox, and then run it down to a standard dual
> 120VAC three prong wall receptacle Of course I would have to run a
> white neutral wire off the subpanel to complete the wiring to the
> recep.
>
> I could always just run a completely seperate 120VAC wire and a white
> nuetral wire from the subpanel and put them on a dedicated breaker to
> provide juice to the recep. I just figure it would be easier to run
> both the 120VAC recep and the compressor motor off the same circuit.
>
> Is that kosher?
No. You could accomplish the same thing by running a small feeder to a
subpanel, but you cannot piggyback a receptacle load on a hot leg running to
a piece of equipment. BTW, the hot legs are not really 120 VAC, that is the
phase to neutral potential but you are using phase to phase and the phase to
phase potential is what is important here. If you have 210V between phases
you may have a 120/208 three phase service to the building, a single phase
service would give you approximately 240 hot leg to hot leg, yet the legs
would still be 120V to neutral. Calling them 120 V legs implies an additive
relationship when you put them together which does not really exist, it only
appears to exist in center tapped single phase systems because of the
symmetry involved.
On Wed, 03 Dec 2003 10:06:45 GMT, -n. put forth the notion that...
> On Wed, 3 Dec 2003 1:27:37 -0500, Anthony wrote
> (in message <[email protected]>):
>
>
> > If the panel you refer to is your service entrance, you *SHOULD* have a
> > bare #6 min/#4 preferred BARE ground wire running from the terminal block
> > which the white wire connects to a ground rod outside your building. This
> > provides the earth ground. As for your installation:
> > Typically, you will use a double breaker, 30A for #10 wire.
> > Pull 3 wires, 1 red, 1 black and 1 bare from your panel to the disconnect
> > box, and the same to your compressor.
> > Red to one hot side, black to the other and ground to the ground lug on
> > the compressor.
> > The ground must also attach via screw, to the disconnect box (if using
> > metal box) This bare ground should connect to the neutral/ground terminal
> > strip in the service panel.
>
> The breaker panel in my residence does have a terminal block that the white
> nuetral wire connects to (the largest white wire that comes from the main
> service panel in the building's basement), and is also where all the white
> neutral wires for the various circuits in my residence also terminate (but no
> bare wires connect to it...indeed, there are no bare wires in my breaker
> panel). Are you suggesting that this terminal block is where I should connect
> the bare ground wire to (instead of just connecting to the panel itself)?
Never connect a ground wire to the neutral bus bar in a subpanel. Your
ground has to connect to the can, preferably by using a ground lug
bolted to the back of the panel.
> > In combination with the ground rod/#6/4 wire this provides a direct earth
> > ground for the compressor.
> >
>
> Thanks.
> -N.
>
>
--
Checkmate
Copyright 2003
all rights reserved
On Sat, 6 Dec 2003 08:24:57 -0600, Rick put forth the notion that...
> According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor with
> a motor designed for 230v AC on a 208v circuit. IR sells a special 208v
> motor for those installations. You have to order it with the correct motor
> on it.
>
> We've tried using the standard 230v motor and had problems with them
> overheating and shorting out. It will run for a while, but eventually the
> motor will fail.
>
> We are seeing more and more 208v in our area instead of 230v. I'm not sure
> of the reason, but most newly constructed areas are being serviced with
> 208v.
>
> Rick
It's a simple matter to get a 240/24 volt transformer, and wire it up in
a boost configuration. This will turn 208 volts into 230.
> "N." <[email protected]> wrote in message
> news:[email protected]...
> > Finally (!) after a two year wait, my building received hookup of the
> > second leg of an electrical service upgrade (delay was due to asbestos
> > contamination issues)...I now have 220VAC availible. Time to hookup my
> > 5HP/80 gallon IR compressor!
> >
> > I have a question regarding grounding that I need to be clear on
> > before proceeding.
> > *[I have copy of the NEC 2002 Codebook in case anyone needs to
> > reference it].
> >
> > Here's the hardware configuration:
> > -Compressor Motor: 5HP/230VAC/ 1 Phase/ 22.5 FLA
> > -Electrical Service Panel:
> > We have BX metal cable in this building which is the local NYC code.
> > The breaker panel in my place has as the main feed a metal Greenfield
> > conduit entering it: the Greenfield carries three wires,
> > white/red/blk. There is NO green ground wire anywhere in this panel.
> > Red connects to one side of the breaker terminal. Black connects to
> > the other side of the breaker terminal. White goes to a seperate
> > non-breaker terminal, and I am assuming the white is thus neutral.
> >
> > Here are the voltage meter readings I get when testing at the breaker
> > panel:
> > Blk/Red =209VAC
> > Blk/Wht =120VAC
> > Red/Wht =120VAC
> > Wht/Service Panel = 0.29 VAC
> > Blk/ Service Panel = 120VAC
> > Red/ Service Panel = 120VAC
> >
> > ------------------------
> > I intend to run BX cable from the service panel to an enclosed metal
> > switchbox: and then a short length of Liquid Tite Flexible Metal
> > Conduit from the switchbox to the compressor motor. I am using 10guage
> > wire for the circuit. Total length of the circuit from panel to motor
> > is approx. 20'.
> >
> > Questions:
> > 1) Will a 230VAC single phase motor run OK on 210VAC service?
> > 2) I need either a Duplex Breaker, or 2 Single Breakers to control the
> > circuit. What should each pole of the breaker be rated at? Is 25 or
> > 30amps
> > correct? Do I need any special 'motor type breaker'?
> > 3)The motor has terminals for 2 wires and 1 ground wire. From my
> > understanding I can run the Red (120VAC) & Blk (120VAC) from the
> > breaker panel to the switchbox, and then from the switchbox onto the
> > motor to their respective terminals. However, what do I use as a
> > ground wire???
> > Can I put a copper grounding screw/lug into the service panel box and
> > run a green ground wire off of that and use it as my ground?
> > 4) There is no need to utilize the white wire in this circuit, correct
> > (unless I decide to place a 120VAC outlet somewhere on the circuit?
> >
> > Thanks a bunch.
> > -N.
> >
> >
> > I have the current NEC codebook but am still perplexed.
> > Thanks for any clarification.
>
>
>
--
Checkmate
Copyright 2003
all rights reserved
In article <[email protected]>, tailslid1
@no.spam.please.bis.midco.net says...
> According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor with
> a motor designed for 230v AC on a 208v circuit.
Rick, do you know what RPM motor I should be using on an older
Ingersoll-Rand Type 30 Model 234C4?
On Sat, 06 Dec 2003 20:51:50 GMT, Ted Edwards put forth the notion
that...
> Rick wrote:
>
> > We are seeing more and more 208v in our area instead of 230v. I'm not sure
> > of the reason, but most newly constructed areas are being serviced with
> > 208v.
>
> Most new areas are seeing three phase power distribution. Single phase
> service is provided by tapping off one phase and neutral. The result is
> 208V.
>
> Ted
One phase and neutral gives you 120 volts.
--
Checkmate
Copyright 2003
all rights reserved
On 6 Dec 2003 11:12:08 -0800, Mike put forth the notion that...
> -n. <[email protected]> wrote
> > Good idea.
> > Thanks to all for the assistance.
> >
> > I have one last question.
>
> You are nuts to get your electrical wiring information from this
> group.
I've been a licensed electrical contractor for 29 years... does that
count?
> In the past some of the information I've seen posted is
> downright dangerous, a lot is just plain wrong, some misguided, some
> pertains to other jurisdictions or situations or is out of date, some
> makes no economic sense. A small part is good sound advice from
> knowledgable professionals who are up on current code. So how do you
> sort it out? Hire an electrician.
>
> mike
>
--
Checkmate
Copyright 2003
all rights reserved
On Sun, 07 Dec 2003 05:57:31 GMT, Ted Edwards put forth the notion
that...
> Checkmate wrote:
>
> > I've been a licensed electrical contractor for 29 years... does that
> > count?
>
> Nope. Considering some of the work I've seen that was done by "licensed
> electrical contractors", that alone doesn't mean much.
From my observations, that's usually because the guy with the license
isn't actually doing the work... he's hiring a bunch of twenty-something
year old's who think they're electricians, and he's not supervising the
job properly. Sometimes incompetence is actually profitable. A good
example is the electrical repair business. The guys that do
troubleshooting and repair usually charge by the hour. Who makes more
money, the guy who knows what he's doing and can find a problem in under
half an hour, or the guy who hasn't got a clue, and spends the whole day
pulling every outlet in the building apart until he stumbles upon the
problem?
I know what you're saying... the advice you get on Usenet is often worth
exactly what you paid for it. On the other hand, there are people out
there who know what they're talking about and don't mind helping people.
If you get enough answers from enough people, you can get a pretty good
idea as to who knows what they're talking about and who's full of shit.
--
Checkmate
Copyright 2003
all rights reserved
On Thu, 11 Dec 2003 08:46:14 GMT, -n. put forth the notion that...
> On Sat, 6 Dec 2003 14:37:52 -0500, Checkmate wrote
> (in message <[email protected]>):
>
> >
> > On Sat, 6 Dec 2003 08:24:57 -0600, Rick put forth the notion that...
> >
> >> According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor
> >> with
> >> a motor designed for 230v AC on a 208v circuit. IR sells a special 208v
> >> motor for those installations. You have to order it with the correct motor
> >> on it.
> >>
> >> We've tried using the standard 230v motor and had problems with them
> >> overheating and shorting out. It will run for a while, but eventually the
> >> motor will fail.
> >>
> >> We are seeing more and more 208v in our area instead of 230v. I'm not sure
> >> of the reason, but most newly constructed areas are being serviced with
> >> 208v.
> >>
> >> Rick
> >
> > It's a simple matter to get a 240/24 volt transformer, and wire it up in
> > a boost configuration. This will turn 208 volts into 230.
>
>
> Checkmate, can you elaborate on this boost transformer setup? Also, any idea
> what the equipment would cost (new or surplus) to gt it done?
> Thanks,
> -N.
Certainly. You take a 240 to 24 volt transformer, and wire the primary
and secondary windings in series by connecting one end of the primary
winding to one end of the secondary winding. Now, you have what's known
as an autotransformer. Next, you connect your 208 volt input to the
opposite end of the primary winding, and the common ends of the primary
and secondary windings. Finally, you connect your output to the same
end of the primary that you connected your input to, plus far end of the
secondary winding, and you'll get 230 volts out. It's important that
you connect the windings so that they're in phase. By that, I mean you
don't want the windings in the primary to be connected to the windings
in the secondary in such a way that one coil is wound clockwise, and the
other is wound counterclockwise. Acme transformer has some excellent
information on this, as well as the correct wiring diagrams for each of
their transformers. Here's the link:
http://www.electricalpowertransformer.com/buck-boost.html
--
Checkmate
Copyright 2003
all rights reserved
On Thu, 11 Dec 2003 08:41:49 GMT, -n. put forth the notion that...
> On Wed, 3 Dec 2003 23:40:33 -0500, ATP wrote
> (in message <[email protected]>):
>
> > Lew Hodgett wrote:
> >> RE: Subject
> >>
> >> Some where in this thread, 209V was noted as a measured voltage.
> >>
> >> If that data is in fact true, you may be getting two legs and a
> >> neutral of a 208Y/120V, 3 phase service.
> >>
> >> If that is true, you will almost certainly burn up a 240V motor
> >> unless you also install a buck-boost transformer for the 240V motor.
> >>
> >> BTW, 208Y/120V is quite common in commercial buildings.
> >>
> >> Be a good idea to reconfirm your supply voltage.
> >
> > Although 208/230 motors are pretty common, he should check the nameplate.
> >
>
> UPDATE:
> I spoke by phone with the electrical contractor who did the install and asked
> him exactly what kind of service I now have. He responded that I have two
> lines at 115VAC with a common nuetral. It is single phase 208VAC service. He
> mentioned that for 230VAC motor, I should do the install for a 220VAC line,
> with double breaker.
> I asked his opinion about running a 230 VAC 1-phase motor on 208 service...he
> said it wouldn't be a problem, at the very worst the motor may run a little
> slow.
What he should have said, is at the worst it may run a little HOT. AC
induction motors turn at a certain speed because of the frequency of the
sine wave, not the amount of voltage. If you give the motor less
voltage than it was designed for, it won't slow down initially, it'll
draw more current, and current equals heat. You really have to lower
the voltage significantly to see a drop in speed, but you don't have to
lower it a whole lot to see an increase in amperage and heat buildup.
Some motors are designed to run on anything between 208 and 230, but not
all of them. If the manufacturer says the motor is okay to run at 208,
that's fine, but don't go by what the contractor is telling you.
--
Checkmate
Copyright 2003
all rights reserved
On Thu, 11 Dec 2003 09:22:04 GMT, -n. put forth the notion that...
> On Wed, 3 Dec 2003 11:27:06 -0500, Anthony wrote
> (in message <[email protected]>):
>
> > -n. <[email protected]> wrote in
> > news:[email protected]:
> >
> >> On Wed, 3 Dec 2003 1:27:37 -0500, Anthony wrote
> >> (in message <[email protected]>):
>
> >>> As for your installation:
> >>> Typically, you will use a double breaker, 30A for #10 wire.
> >>> Pull 3 wires, 1 red, 1 black and 1 bare from your panel to the
> >>> disconnect box, and the same to your compressor.
> >>> Red to one hot side, black to the other and ground to the ground lug
> >>> on the compressor.
> >>> The ground must also attach via screw, to the disconnect box (if
> >>> using metal box) This bare ground should connect to the
> >>> neutral/ground terminal strip in the service panel.
>
> To reiterate:
> I am clear on this above wiring scheme except for one detail. The panel I am
> starting from is a subpanel and it does not contain any grounding bar or
> grounding terminal. In this case, does my ground wire need to be bare, or
> will green insulated work just as well?
> I pull red, black, and green insulated ground (all 10awg). Red goes to one
> pole of 30A dual breaker, black goes to other pole of breaker, for ground I
> drill a hole into the subpanel box itself then scrape some paint away and
> screw in a copper grounding lug. I run these three wires through BX cable to
> a 30AMP rated disconnect box, making certain to affix the ground to the
> disconnect box via a screw and to acheive good continuity. THese 3 wires exit
> the disconnect box and are encased in liquid tite flexible metal conduit
> which goes to the compressor motor/switch. Again, black and red connect to
> respective lugs on the motor and the ground goes to ground lug on motor.
>
> [If I find out a boost transformer is absolutely needed to boost my 208VAC
> service to run the 230VAC motor, I will research that and add it t the
> system].
> If I wish to install a 120VAC recep box in the same room as the compressor,
> it must be on a seperate ciruit with a dedicated breaker, NOT off the hot
> wires used in the compressor circuit.
>
> The only other modification I can forsee doing to this compressor circuit
> would be to install a 230VAC receptacle in the wall and a mating 230VAC
> plug/cordset [10awg, 3 wire: red, black, green] on the compressor .... and
> run that downstream from the disconnect box as an option instead of the
> hardwired liquid tite flexible metal conduit.
>
> What do you think guys, does that sound like it confirms to code?
> Thanks.
You've got the right idea, and that's how I'd do it. Whether it
conforms to code is another issue. Offhand, I'd say yes, but every
jurisdiction has their own little quirks... what kind of conduit they
want you to use, etc. I've seen some weird demands from even weirder
inspectors. If you're going to get it permitted, it's best to run your
plans by an inspector first and get his blessings, so to speak.
--
Checkmate
Copyright 2003
all rights reserved
On Sat, 13 Dec 2003 00:49:19 GMT, -n. put forth the notion that...
> On Thu, 11 Dec 2003 11:58:40 -0500, Checkmate wrote
> (in message <[email protected]>):
>
> >
> >
> >> I asked his opinion about running a 230 VAC 1-phase motor on 208
> >> service...he
> >> said it wouldn't be a problem, at the very worst the motor may run a
> >> little
> >> slow.
> >
> > What he should have said, is at the worst it may run a little HOT. AC
> > induction motors turn at a certain speed because of the frequency of the
> > sine wave, not the amount of voltage. If you give the motor less
> > voltage than it was designed for, it won't slow down initially, it'll
> > draw more current, and current equals heat. You really have to lower
> > the voltage significantly to see a drop in speed, but you don't have to
> > lower it a whole lot to see an increase in amperage and heat buildup.
> > Some motors are designed to run on anything between 208 and 230, but not
> > all of them. If the manufacturer says the motor is okay to run at 208,
> > that's fine, but don't go by what the contractor is telling you.
> >
>
> To reiterate, the supply voltage I measured is 209VAC between the two hots.
> The motor states 230VAC single phase, 1.25 service factor, and is thermally
> proteted with a reset button.
> Again, the electrical contractor who owns the bizz that did the install
> states I have single phase service @ 208VAC....although many of you are
> claiming that this latter data must be incorrect. I will need to bug that
> contractor again and discuss the doubts expressed here.
> I haven't spoken with the motor manufacturer to check if the motor can run
> on 208-230VAC, although it most certainly does not list 208-230VAC on the
> nameplate.
> Is there a way for me to check and confirm the phase of the service I have (1
> or 3 phase) with only a voltage/amp meter?
> Lastly, going with only the data I now have, many of you have expressed
> concern that the motor would run HOT and possibly burn out, short, or
> experience a reduced servie life if it were connected as is without a boost
> transformer. Hypothetically, wouldn't the thermal protection/reset circuit in
> the motor protect it before damage was done by shutting off the motor in the
> event that it did experience an increase in temp?
>
> Thanks again.
If you have a 120/208 volt single phase service, it's derived from two
legs and a neutral from a three phase service somewhere along the line.
If your motor has a thermal overload switch, it should shut off if it's
working properly, however this isn't going to solve your problem.
--
Checkmate
Copyright 2003
all rights reserved
On 13 Dec 2003 01:09:00 -0500, DoN. Nichols put forth the notion that...
> In article <[email protected]>,
> Grant Erwin <[email protected]> wrote:
> >You almost certainly don't have three phase service unless you live in
> >some space that used to be industrial.
>
> What about a large apartment building? Those are probably fed
> three phase, since all totaled, there is a *lot* of load, and this will
> distribute it fairly evenly.
Most likely they're feeding the building with three phase, but splitting
it up to the individual apartments with approximately 1/3 of the units
on AB, BC, and CA. That's pretty unusual in residential buildings. Too
bad he can't pull the third leg up to his unit, but he's most likely on
a single phase meter unless there's just one meter for everybody.
> Anyway -- if you are measuring 120V from neutral to both hots,
> but 209 between them, you *are* getting two phases of a 208V three phase
> feed.
>
> >I don't think that reset button will protect you from chronic undervoltage.
> >How big a motor is this? If it's just a horse or two, then your solution is
> >really simple - buy a cheap buck/boost transformer, hook it up, and have a
> >nice cup of coffee!
>
> Agreed -- that is the safest thing to do.
>
> Good Luck,
> DoN.
>
>
--
Checkmate
Copyright 2003
all rights reserved
Roger Hull <[email protected]> writes:
>On Tue, 2 Dec 2003 10:10:12 -0800, N. wrote
>> Questions:
>> 1) Will a 230VAC single phase motor run OK on 210VAC service?
>> 2) I need either a Duplex Breaker, or 2 Single Breakers to control the
>> circuit. What should each pole of the breaker be rated at? Is 25 or
>> 30amps
>> correct? Do I need any special 'motor type breaker'?
>> 3)The motor has terminals for 2 wires and 1 ground wire. From my
>> understanding I can run the Red (120VAC) & Blk (120VAC) from the
>> breaker panel to the switchbox, and then from the switchbox onto the
>> motor to their respective terminals. However, what do I use as a
>> ground wire???
>> Can I put a copper grounding screw/lug into the service panel box and
>> run a green ground wire off of that and use it as my ground?
>> 4) There is no need to utilize the white wire in this circuit, correct
>> (unless I decide to place a 120VAC outlet somewhere on the circuit?
>>
>> Thanks a bunch.
>> -N.
>>
>>
>> I have the current NEC codebook but am still perplexed.
>> Thanks for any clarification.
>
>I have no knowledge of NYC local codes, but as far as the national code goes:
>
>1. Yes
>2. A double breaker is required. 30 Amp would be correct for #10 wire.
>3. The ground is through the shell of the BX cable. If your flex does not
>complete the grounding path a bonding wire must be installed.
>A copper lug in the panel is not necessary, I am unclear as to if the panel
>is your "Service entrance" or a subpanel. If a subpanel a lug is NOT allowed.
Not quite. If it is a subpanel, bonding the grounded conductor and the
grounding conductor is not allowed. It is common for a subpanel to have
a ground bar bonded to the panel (the panel is required to be bonded
to the grounding conductor, but that happens through the BX shell as
pointed out in this case).
The NEC no longer allows the armor on some armored cables to be used
as the grounding conductor. This typically applies to flexible metal
conduit, but may also apply to BX armored cable. Check the book.
>4. Correct.
>
scott
-n. <[email protected]> wrote in
news:[email protected]:
> On Wed, 3 Dec 2003 1:27:37 -0500, Anthony wrote
> (in message <[email protected]>):
>
>
>> If the panel you refer to is your service entrance, you *SHOULD* have
>> a bare #6 min/#4 preferred BARE ground wire running from the terminal
>> block which the white wire connects to a ground rod outside your
>> building. This provides the earth ground. As for your installation:
>> Typically, you will use a double breaker, 30A for #10 wire.
>> Pull 3 wires, 1 red, 1 black and 1 bare from your panel to the
>> disconnect box, and the same to your compressor.
>> Red to one hot side, black to the other and ground to the ground lug
>> on the compressor.
>> The ground must also attach via screw, to the disconnect box (if
>> using metal box) This bare ground should connect to the
>> neutral/ground terminal strip in the service panel.
>
> The breaker panel in my residence does have a terminal block that the
> white nuetral wire connects to (the largest white wire that comes from
> the main service panel in the building's basement), and is also where
> all the white neutral wires for the various circuits in my residence
> also terminate (but no bare wires connect to it...indeed, there are no
> bare wires in my breaker panel). Are you suggesting that this terminal
> block is where I should connect the bare ground wire to (instead of
> just connecting to the panel itself)?
>
>
>> In combination with the ground rod/#6/4 wire this provides a direct
>> earth ground for the compressor.
>>
>
> Thanks.
> -N.
>
>
Obviously this system is grounded through the conduit (not my preference,
but ok)
In this case, the metal flex conduit from the breaker panel to the
disconnect box obviously serves as ground path. You will probably need a
bonding wire (bare or green) from the ground lug on the compressor to the
ground lug on the disconnect box (the actual box itself).
--
Anthony
You can't 'idiot proof' anything....every time you try, they just make
better idiots.
Remove sp to reply via email
Roger Hull <[email protected]> wrote in
news:[email protected]:
>>
>>
>> I have the current NEC codebook but am still perplexed.
>> Thanks for any clarification.
>
> I have no knowledge of NYC local codes, but as far as the national
> code goes:
>
> 1. Yes
> 2. A double breaker is required. 30 Amp would be correct for #10 wire.
> 3. The ground is through the shell of the BX cable. If your flex does
> not complete the grounding path a bonding wire must be installed.
> A copper lug in the panel is not necessary, I am unclear as to if the
> panel is your "Service entrance" or a subpanel. If a subpanel a lug is
> NOT allowed. 4. Correct.
>
> Roger in Vegas
> Worlds Greatest Impulse Buyer
>
>
If the panel you refer to is your service entrance, you *SHOULD* have a
bare #6 min/#4 preferred BARE ground wire running from the terminal block
which the white wire connects to a ground rod outside your building. This
provides the earth ground. As for your installation:
Typically, you will use a double breaker, 30A for #10 wire.
Pull 3 wires, 1 red, 1 black and 1 bare from your panel to the disconnect
box, and the same to your compressor.
Red to one hot side, black to the other and ground to the ground lug on
the compressor.
The ground must also attach via screw, to the disconnect box (if using
metal box) This bare ground should connect to the neutral/ground terminal
strip in the service panel.
In combination with the ground rod/#6/4 wire this provides a direct earth
ground for the compressor.
--
Anthony
You can't 'idiot proof' anything....every time you try, they just make
better idiots.
Remove sp to reply via email
N. wrote:
> On Tue, 2 Dec 2003 18:08:53 -0400, Scott Lurndal wrote
> (in message <[email protected]>):
>
>> Roger Hull <[email protected]> writes:
>>> On Tue, 2 Dec 2003 10:10:12 -0800, N. wrote
>>
>>>> Questions:
>>>> 1) Will a 230VAC single phase motor run OK on 210VAC service?
>>>> 2) I need either a Duplex Breaker, or 2 Single Breakers to control
>>>> the circuit. What should each pole of the breaker be rated at? Is
>>>> 25 or 30amps
>>>> correct? Do I need any special 'motor type breaker'?
>>>> 3)The motor has terminals for 2 wires and 1 ground wire. From my
>>>> understanding I can run the Red (120VAC) & Blk (120VAC) from the
>>>> breaker panel to the switchbox, and then from the switchbox onto
>>>> the motor to their respective terminals. However, what do I use as
>>>> a ground wire???
>>>> Can I put a copper grounding screw/lug into the service panel box
>>>> and run a green ground wire off of that and use it as my ground?
>>>> 4) There is no need to utilize the white wire in this circuit,
>>>> correct (unless I decide to place a 120VAC outlet somewhere on the
>>>> circuit?
>>>>
>>>> Thanks a bunch.
>>>> -N.
>>>>
>>>>
>>>> I have the current NEC codebook but am still perplexed.
>>>> Thanks for any clarification.
>>>
>>> I have no knowledge of NYC local codes, but as far as the national
>>> code goes:
>>>
>>> 1. Yes
>>> 2. A double breaker is required. 30 Amp would be correct for #10
>>> wire.
>>> 3. The ground is through the shell of the BX cable. If your flex
>>> does not complete the grounding path a bonding wire must be
>>> installed. A copper lug in the panel is not necessary, I am unclear
>>> as to if the panel
>>> is your "Service entrance" or a subpanel. If a subpanel a lug is NOT
>>> allowed.
>>
>> Not quite. If it is a subpanel, bonding the grounded conductor and
>> the grounding conductor is not allowed. It is common for a subpanel
>> to have a ground bar bonded to the panel (the panel is required to
>> be bonded to the grounding conductor, but that happens through the
>> BX shell as pointed out in this case).
>>
>> The NEC no longer allows the armor on some armored cables to be used
>> as the grounding conductor. This typically applies to flexible metal
>> conduit, but may also apply to BX armored cable. Check the book.
>>
>>> 4. Correct.
>>>
>>
>> scott
>
>
> Regarding service panels: The basement houses the 'Main Service Feed
> Panel' for the building. I live on the 4th floor, and I have a
> 'Breaker Panel' that is fed from that main panel: a Greenfield cable
> rises 4 floors and enters my 'Breaker Panel'...it is the ONLY panel
> in my living space. Nomenclature: does this 'Breaker Panel'
> generally qualify as a 'subpanel', or conversely, would a 'subpanel'
> be the nomenclature for any additional breaker panel installed along
> a new circuit I run downstream from my 'Breaker Panel'?
>
> Yes, I had assumed the ground to be the shell of the BX cable...there
> is no 'ground bar' in my breaker panel.
> In my space, none of the receptacles have a ground wire .... I assume
> the BX cable itself to be the ground.
>
> Regarding grounding the motor to the 'Breaker Panel': I was thinking
> the BX/Flexible Metal Conduit would suffice, but I had purchased a
> little copper screw/terminal to screw to the 'Breaker Panel"
> (refering to it as a 'lug' in my initial post). I'm still a little
> unclear as to general grounding/bonding practices, and was wondering
> if the BX was sufficient for the ground in my circuit, or if I would
> need to install a seperate green ground wire off the 'lug' from the
> 'Breaker Panel' and connect that to the motor.
>
> When the electrical upgrade was made, the contractor installed a new
> receptacle and ran BX back to the 'Breaker Panel"...there is no
> seperate ground wire in this circuit, so, yes, I'm assuming the BX is
> functioning as the ground.
> What are the views on the best way for me to execute the ground for
> this motor circuit?
>
> Thanks again.
> -N.
BX is a lot different than Flexible Metal Conduit. Run the separate ground.
When you install the lug in the subpanel scrape the paint off the back of
the subpanel behind the lug.
In article <[email protected]>,
Grant Erwin <[email protected]> wrote:
>You almost certainly don't have three phase service unless you live in
>some space that used to be industrial.
What about a large apartment building? Those are probably fed
three phase, since all totaled, there is a *lot* of load, and this will
distribute it fairly evenly.
Anyway -- if you are measuring 120V from neutral to both hots,
but 209 between them, you *are* getting two phases of a 208V three phase
feed.
>I don't think that reset button will protect you from chronic undervoltage.
>How big a motor is this? If it's just a horse or two, then your solution is
>really simple - buy a cheap buck/boost transformer, hook it up, and have a
>nice cup of coffee!
Agreed -- that is the safest thing to do.
Good Luck,
DoN.
--
Email: <[email protected]> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
-n. <[email protected]> wrote
> Good idea.
> Thanks to all for the assistance.
>
> I have one last question.
You are nuts to get your electrical wiring information from this
group. In the past some of the information I've seen posted is
downright dangerous, a lot is just plain wrong, some misguided, some
pertains to other jurisdictions or situations or is out of date, some
makes no economic sense. A small part is good sound advice from
knowledgable professionals who are up on current code. So how do you
sort it out? Hire an electrician.
mike
On Thu, 11 Dec 2003 08:49:29 GMT, -n. <[email protected]> wrote:
>On Sat, 6 Dec 2003 10:24:57 -0500, Rick wrote
>(in message <[email protected]>):
>
>> According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor with
>> a motor designed for 230v AC on a 208v circuit. IR sells a special 208v
>> motor for those installations. You have to order it with the correct motor
>> on it.
>>
>> We've tried using the standard 230v motor and had problems with them
>> overheating and shorting out. It will run for a while, but eventually the
>> motor will fail.
>>
>> We are seeing more and more 208v in our area instead of 230v. I'm not sure
>> of the reason, but most newly constructed areas are being serviced with
>> 208v.
>
>
>Rick,
>That is not news I want to hear.
>This goes for running 230VAC single phase on 208VAC single phase service?
>I had always thought there was some lattitude in voltage ratings of motors.
>Can anyone elaborate on why this would cause overheatng/shorting? Trying to
>learn something along the way.
>-N.
There is some latitude. A nominal 230 motor will typically run fine on
voltages between 220 and 240. But 208 is too low unless the motor is
specially designed to handle it. Horsepower is voltage times current
divided by 746. For a given horsepower demand, a lower supply voltage
means the motor must draw more current to provide rated power.
Heat build up in the motor is a function of current squared times winding
resistance. So the more current the motor has to draw to meet the load
power demand, the hotter the motor will run. Notice that heat is a function
of the square of current, so it doesn't take a whole lot of excess current
to get the motor very hot.
Motors are designed for a specific maximum temperature. Exceeding that
temperature will greatly shorten the life of the motor, ie you'll let out all the
magic smoke if you persist in running a motor at its rated output power
with lower than rated supply voltage.
Note that you could probably get away with running a 230 volt motor at lower
than design voltage if you don't draw anything approaching its rated power
output from it. In other words, if the motor is oversize for the load power
demand, it'll tolerate running on a lower voltage. That's how motors rated
to run on 208 to 240 are designed, ie they're bigger (larger windings and
or more cooling air) than their nameplate hp would otherwise require them
to be. That costs money, so equipment manufacturers typically don't use
such motors unless you pay extra for them.
Gary
In article <[email protected]>, -n. <[email protected]> wrote:
[snip]
>
>UPDATE:
>I spoke by phone with the electrical contractor who did the install and asked
>him exactly what kind of service I now have. He responded that I have two
>lines at 115VAC with a common nuetral. It is single phase 208VAC service.
This is extremely doubtful. 208V is THREE-phase, not single-phase. You might
have two legs of a three-phase service. What voltage do you measure between
the two 115V legs?
> He
>mentioned that for 230VAC motor, I should do the install for a 220VAC line,
>with double breaker.
>I asked his opinion about running a 230 VAC 1-phase motor on 208 service...he
>said it wouldn't be a problem, at the very worst the motor may run a little
>slow.
You need to get a _competent_ electrician, ASAP. This guy doesn't have a clue.
Unless the motor was designed to be run on 208 3-phase, you'll burn it up in a
hurry.
--
Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
"ATPwrites:
> His "electrician" is definitely clueless. There are plenty of 208/230
single
> phase motors however. Otherwise the vast number of commercial and
> institutional customers with 208Y service would not be able to use them.
Typically motors that will operate at either 208V or 240V are more expensive
than the equivalent motor wound to operate at 230V.
Over the years, have sold a lot of buck-boost transformers to solve this
problem.
Get one, install it, then get a beer, and enjoy life.
--
Lew
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: <http://home.earthlink.net/~lewhodgett> for Pictures
Checkmate <[email protected]> wrote:
> Most likely they're feeding the building with three phase, but splitting
> it up to the individual apartments with approximately 1/3 of the units
> on AB, BC, and CA. That's pretty unusual in residential buildings.
^^^^^^^
I assume you meant to say "usual" there?
I used to live in a 55 unit apartment building, and the wiring was done
exactly that way. Each apartment had a washer/dryer, with a "220"
outlet for the dryer. The dryer motor ran on 110 and the "220" was just
for the electric heating element, so I imagine all that happened is it
didn't get as hot as it should have.
Roy Smith wrote:
> Checkmate <[email protected]> wrote:
>
>>Most likely they're feeding the building with three phase, but splitting
>>it up to the individual apartments with approximately 1/3 of the units
>>on AB, BC, and CA. That's pretty unusual in residential buildings.
>
> ^^^^^^^
>
> I assume you meant to say "usual" there?
>
> I used to live in a 55 unit apartment building, and the wiring was done
> exactly that way. Each apartment had a washer/dryer, with a "220"
> outlet for the dryer. The dryer motor ran on 110 and the "220" was just
> for the electric heating element, so I imagine all that happened is it
> didn't get as hot as it should have.
I got this hilarious mental image of a home
shop type with a Bridgeport in his bedroom
and extension cords running to the apartments
on either side of him to get the other two
phases...
According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor with
a motor designed for 230v AC on a 208v circuit. IR sells a special 208v
motor for those installations. You have to order it with the correct motor
on it.
We've tried using the standard 230v motor and had problems with them
overheating and shorting out. It will run for a while, but eventually the
motor will fail.
We are seeing more and more 208v in our area instead of 230v. I'm not sure
of the reason, but most newly constructed areas are being serviced with
208v.
Rick
"N." <[email protected]> wrote in message
news:[email protected]...
> Finally (!) after a two year wait, my building received hookup of the
> second leg of an electrical service upgrade (delay was due to asbestos
> contamination issues)...I now have 220VAC availible. Time to hookup my
> 5HP/80 gallon IR compressor!
>
> I have a question regarding grounding that I need to be clear on
> before proceeding.
> *[I have copy of the NEC 2002 Codebook in case anyone needs to
> reference it].
>
> Here's the hardware configuration:
> -Compressor Motor: 5HP/230VAC/ 1 Phase/ 22.5 FLA
> -Electrical Service Panel:
> We have BX metal cable in this building which is the local NYC code.
> The breaker panel in my place has as the main feed a metal Greenfield
> conduit entering it: the Greenfield carries three wires,
> white/red/blk. There is NO green ground wire anywhere in this panel.
> Red connects to one side of the breaker terminal. Black connects to
> the other side of the breaker terminal. White goes to a seperate
> non-breaker terminal, and I am assuming the white is thus neutral.
>
> Here are the voltage meter readings I get when testing at the breaker
> panel:
> Blk/Red =209VAC
> Blk/Wht =120VAC
> Red/Wht =120VAC
> Wht/Service Panel = 0.29 VAC
> Blk/ Service Panel = 120VAC
> Red/ Service Panel = 120VAC
>
> ------------------------
> I intend to run BX cable from the service panel to an enclosed metal
> switchbox: and then a short length of Liquid Tite Flexible Metal
> Conduit from the switchbox to the compressor motor. I am using 10guage
> wire for the circuit. Total length of the circuit from panel to motor
> is approx. 20'.
>
> Questions:
> 1) Will a 230VAC single phase motor run OK on 210VAC service?
> 2) I need either a Duplex Breaker, or 2 Single Breakers to control the
> circuit. What should each pole of the breaker be rated at? Is 25 or
> 30amps
> correct? Do I need any special 'motor type breaker'?
> 3)The motor has terminals for 2 wires and 1 ground wire. From my
> understanding I can run the Red (120VAC) & Blk (120VAC) from the
> breaker panel to the switchbox, and then from the switchbox onto the
> motor to their respective terminals. However, what do I use as a
> ground wire???
> Can I put a copper grounding screw/lug into the service panel box and
> run a green ground wire off of that and use it as my ground?
> 4) There is no need to utilize the white wire in this circuit, correct
> (unless I decide to place a 120VAC outlet somewhere on the circuit?
>
> Thanks a bunch.
> -N.
>
>
> I have the current NEC codebook but am still perplexed.
> Thanks for any clarification.
You almost certainly don't have three phase service unless you live in
some space that used to be industrial.
I don't think that reset button will protect you from chronic undervoltage.
How big a motor is this? If it's just a horse or two, then your solution is
really simple - buy a cheap buck/boost transformer, hook it up, and have a
nice cup of coffee!
Grant Erwin
-n. wrote:
> On Thu, 11 Dec 2003 11:58:40 -0500, Checkmate wrote
> (in message <[email protected]>):
>
>
>>
>>>I asked his opinion about running a 230 VAC 1-phase motor on 208
>>>service...he
>>>said it wouldn't be a problem, at the very worst the motor may run a
>>>little
>>>slow.
>>
>>What he should have said, is at the worst it may run a little HOT. AC
>>induction motors turn at a certain speed because of the frequency of the
>>sine wave, not the amount of voltage. If you give the motor less
>>voltage than it was designed for, it won't slow down initially, it'll
>>draw more current, and current equals heat. You really have to lower
>>the voltage significantly to see a drop in speed, but you don't have to
>>lower it a whole lot to see an increase in amperage and heat buildup.
>>Some motors are designed to run on anything between 208 and 230, but not
>>all of them. If the manufacturer says the motor is okay to run at 208,
>>that's fine, but don't go by what the contractor is telling you.
>>
>
>
> To reiterate, the supply voltage I measured is 209VAC between the two hots.
> The motor states 230VAC single phase, 1.25 service factor, and is thermally
> proteted with a reset button.
> Again, the electrical contractor who owns the bizz that did the install
> states I have single phase service @ 208VAC....although many of you are
> claiming that this latter data must be incorrect. I will need to bug that
> contractor again and discuss the doubts expressed here.
> I haven't spoken with the motor manufacturer to check if the motor can run
> on 208-230VAC, although it most certainly does not list 208-230VAC on the
> nameplate.
> Is there a way for me to check and confirm the phase of the service I have (1
> or 3 phase) with only a voltage/amp meter?
> Lastly, going with only the data I now have, many of you have expressed
> concern that the motor would run HOT and possibly burn out, short, or
> experience a reduced servie life if it were connected as is without a boost
> transformer. Hypothetically, wouldn't the thermal protection/reset circuit in
> the motor protect it before damage was done by shutting off the motor in the
> event that it did experience an increase in temp?
>
> Thanks again.
>
Jim,
I honestly don't know the answer to that question, and I don't have my work
resources available to me right now.
You may find an answer here:
http://air.irco.com/index.asp
Rick
"Jim Kovar" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, tailslid1
> @no.spam.please.bis.midco.net says...
> > According to Ingersoll Rand (I am a dealer) you CANNOT run a compressor
with
> > a motor designed for 230v AC on a 208v circuit.
>
> Rick, do you know what RPM motor I should be using on an older
> Ingersoll-Rand Type 30 Model 234C4?
RE: Subject
Some where in this thread, 209V was noted as a measured voltage.
If that data is in fact true, you may be getting two legs and a neutral of a
208Y/120V, 3 phase service.
If that is true, you will almost certainly burn up a 240V motor unless you
also install a buck-boost transformer for the 240V motor.
BTW, 208Y/120V is quite common in commercial buildings.
Be a good idea to reconfirm your supply voltage.
--
Lew
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: <http://home.earthlink.net/~lewhodgett> for Pictures