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Old 08-24-2012, 01:10 PM   #1
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Circuit for an air compressor


I have an 5HP air compressor. The motor runs on 230 volts. I want to install a dedicated power line to the compressor. My question is How do I get 230 volts. I thought you have 110 volts, then you have 2 pole single phase with 220 volts. Sooo how do I get 230V. And what AWG should I run, assuming someone can tell me about the 230 thingie.

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Old 08-24-2012, 01:31 PM   #2
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Circuit for an air compressor


There are enough electricians here that I will leave the particulars to them, but, in the mean time, you may want to also provide the full load amps for the motor. Also, you did not mention it, so did your air compressor come with a magnetic starter? If not, what is the RPM of the motor?

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Old 08-24-2012, 01:32 PM   #3
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Circuit for an air compressor


The best way for you to get the "230 thingy" is to call an electrician and get an estimate on how much they will charge you to install this circuit.
It will be money well spent.
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Old 08-24-2012, 01:33 PM   #4
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Originally Posted by DexterII View Post
Also, you did not mention it, so did your air compressor come with a magnetic starter? If not, what is the RPM of the motor?
Can you tell me what having a starter has to do with it? And while we're on the subject what in the world would the RPMs have to do with it???
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Old 08-24-2012, 02:40 PM   #5
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Circuit for an air compressor


Simply a matter of inquiring if the OP had what he needed to run his air compressor. A conventional 5 H.P. air compressor, with 1725-1750 RPM motor, needs a magnetic starter, whereas a lot of the "cheater" models, with motors in the 3450 RPM range are often run without starters. I happen to agree that he should hire an electrician to wire it, but, in case he needs one and doesn't have it, I also have found that it is often easier to obtain the correct size starter from the air compressor supplier than otherwise.
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Old 08-24-2012, 02:51 PM   #6
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Circuit for an air compressor


First of all, I have to say WOW!

The 230V listed on the motor is nominal voltage. Your house can operate anywhere from 110V to 121V on one leg, assuming nominal voltage is 115V. That is 95% to 105%, per NEC. So, the 230V is the nominal voltage across the two 115V legs.

Your compressor will run off the slightly reduced voltage with no problem. You should probably use a 30 Amp double pole breaker and #10 copper wire.
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Old 08-24-2012, 05:16 PM   #7
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The 230V listed on the motor is nominal voltage. Your house can operate anywhere from 110V to 121V on one leg, assuming nominal voltage is 115V. That is 95% to 105%, per NEC. So, the 230V is the nominal voltage across the two 115V legs.
Nominal voltage in the US is 120/240v. The typical voltage in my area is closer to 125/249V.
The fact that the compressor is rated for 230v is a non-issue.



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Your compressor will run off the slightly reduced voltage with no problem. You should probably use a 30 Amp double pole breaker and #10 copper wire.
WHAT are you basing this on? The fact that hte OP told us his compressor is "5HP"??
I bet this "5HP" compressor is rate for 15A.
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Old 08-24-2012, 06:31 PM   #8
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Circuit for an air compressor


Well I guess when I asked for advice I did not think I would start a firestorm over it. No, I will not hire an electrician to do the wiring. I know how to do. The mechanical stuff was not the question I asked. The question was about voltage. But I think I now have the answer. I agree what was said about nominal voltage, etc. I've got it figured out now.

Thank you all
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Old 08-24-2012, 06:55 PM   #9
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Circuit for an air compressor


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Well I guess when I asked for advice I did not think I would start a firestorm over it.

So you didn't read the fine print when you signed up here, did you?
All electrical questions and subsequent answers are hereby referred to as the "FIRESTORM FORUM" And you saying you have it figured out is not the end of it....it will go on and on and on.
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Old 08-24-2012, 07:09 PM   #10
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Circuit for an air compressor


Quote:
Originally Posted by maddog1 View Post
Well I guess when I asked for advice I did not think I would start a firestorm over it. No, I will not hire an electrician to do the wiring. I know how to do. The mechanical stuff was not the question I asked. The question was about voltage. But I think I now have the answer. I agree what was said about nominal voltage, etc. I've got it figured out now.

Thank you all
It's funny how over dramatic some people get. "Fire Storm"?? OK.


Let me ask you, since you say you've got it figured out; do you what amperage circuit you are going to run?

Sorry if my "hire and electrician" comment upset you. If you read the original post from my perspective, judging by your comments you'd understand how in my opinion you do not seem nearly experienced enough.
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Old 08-24-2012, 08:38 PM   #11
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Circuit for an air compressor


i have to admit, i thought the same thing at first, anytime someone says "230v thingy" warning bells go off.

if he goes with a #10 it will cover his butt. Manufacturer may recommend a 40A but that's overkill. If it's a standard 5hp it will llikely draw just over 20A.
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Old 08-24-2012, 09:06 PM   #12
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Circuit for an air compressor


#10 will work if the terminals are 75C, otherwise #8. As for the OCPD, 250% of 28A is 56A. SO a 60A breaker is needed. I'm curious as to what the installation instructios require.
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Old 08-24-2012, 09:06 PM   #13
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i have to admit, i thought the same thing at first, anytime someone says "230v thingy" warning bells go off.

if he goes with a #10 it will cover his butt. Manufacturer may recommend a 40A but that's overkill. If it's a standard 5hp it will llikely draw just over 20A.
28 amps
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Old 08-24-2012, 09:41 PM   #14
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Circuit for an air compressor


Quote:
Originally Posted by electures

28 amps
Hp doesn't translate directly into amps in this case. It may have a much lower running amps as speedy already stated. Breaker gets sized off the Fla which op didn't tell us
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Old 08-24-2012, 09:52 PM   #15
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Circuit for an air compressor


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Originally Posted by andrew79 View Post
Hp doesn't translate directly into amps in this case. It may have a much lower running amps as speedy already stated. Breaker gets sized off the Fla which op didn't tell us
FLA has to be sized from 430.247. I'm still curious about manufacturers instructions though.

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