Circuit for an air compressor

frenchelectrican · 08-25-2012, 12:57 AM

Quote:

Originally Posted by maddog1

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

That is not the " best " answer there. Did you ever look at the motour manufacter nameplate for all the infomation there ??

That is the only way we can able sized the circuit properly due there is a resdentail grade compressour and commercal / industrail compressour both are differnt on them ditto with the motour.

So post the voltage et amps even you did see " SPL " on the HP location on the nameplate.

Merci,
Marc

mpoulton · 08-25-2012, 01:51 AM

Quote:

Originally Posted by electures

As for the OCPD, 250% of 28A is 56A. SO a 60A breaker is needed.

I'm curious as to why you keep saying this. Any time there's a thread about motor OCPD sizing, you always say that the OCPD MUST be sized according to the table. That's just not true. The table specifies the MAXIMUM OCPD allowed, not the EXACT size required. The language of the code is clear. He could use up to a 60A breaker. He could also use a breaker as small as the FLA rating. There is absolutely no requirement that anyone use the largest breaker allowed by that table, nor is it necessarily a good idea. Using the smallest OCPD that doesn't trip on startup is a better idea, since that will provide the fastest protection in case of a mechanical failure seizing the motor.

kbsparky · 08-25-2012, 04:26 AM

Quote:

Originally Posted by electures

FLA has to be sized from 430.247. I'm still curious about manufacturers instructions though.

In most cases, yes. But when dealing with compressors, especially ones that are marketed to consumers, I'd be willing to bet the farm that his compressor is NOT an actual 5 HP. It may be advertised as such, but if one were to take the actual amps of such a beast, one would be able to determine that it's more like 1½ actual HP.

Which would operate just fine on a 15 Amp circuit as stated elsewhere in this thread.

Without the nameplate information, we are stabbing in the dark here.

Tell you what: Next time you are out shopping at a place like Sears, or Lowes, etc. go have a look at their air compressors. Look for one that is advertised as 5HP in big letters on the signage. Then take a close look at the nameplate on the actual motor.

The nameplate will NOT state "5 HP" on it. That will be left blank, or have something stupid like "spl" or some other such nonsense on it.

Those manufacturers should be shot. They get their advertised 5HP ratings from the LRA of the motor, not the actual delivered hp from a running motor/compressor. And the regulatory folks who allowed this nonsense should be shot as well.

electures · 08-25-2012, 09:25 AM

Quote:

Originally Posted by kbsparky

In most cases, yes. But when dealing with compressors, especially ones that are marketed to consumers, I'd be willing to bet the farm that his compressor is NOT an actual 5 HP. It may be advertised as such, but if one were to take the actual amps of such a beast, one would be able to determine that it's more like 1½ actual HP.

Which would operate just fine on a 15 Amp circuit as stated elsewhere in this thread.

Without the nameplate information, we are stabbing in the dark here.

Tell you what: Next time you are out shopping at a place like Sears, or Lowes, etc. go have a look at their air compressors. Look for one that is advertised as 5HP in big letters on the signage. Then take a close look at the nameplate on the actual motor.

The nameplate will NOT state "5 HP" on it. That will be left blank, or have something stupid like "spl" or some other such nonsense on it.

Those manufacturers should be shot. They get their advertised 5HP ratings from the LRA of the motor, not the actual delivered hp from a running motor/compressor. And the regulatory folks who allowed this nonsense should be shot as well.

Agreed. Which is why a picture of the nameplate or the model number or instructions would be nice.

andrew79 · 08-25-2012, 01:20 PM

actually it still hasn't been answered

. he asked what awg but we need to know what the nameplate says for that.

Stubbie · 08-25-2012, 01:22 PM

Quote:

Originally Posted by maddog1

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.

Maddog1

This is your first post ... and you actually thought someone could tell you what wire amperage to run based on this information?

AS for the 230 volt 'thingie I thought you were acussing others of not being able to spell.....

Here is IMO how you should have begun your inquiry ..

I am a novice at electrical and I'm needing information on how to run the correct wiring to operate a 5 hp air compressor. If you will tell me the information I need to have I will supply it to you .... thanks.

Now that wasn't so hard was it ...

Instead you supply needless information about how you obviously know zilch about air compressors and nothing about electricty and then you end your response trying to be cute.

As said earlier you need someone with just a little knowledge about what your wanting to do ... an electrician comes to mind.

Good Luck

**beenthere** · 08-25-2012, 04:12 PM

Question asked, question answered. Nothing to be gained by the OP from this thread due to how it is now side tracked with bickering, thread closed.