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Re: Air compressor electric circuit

To: shop-talk@autox.team.net
Subject: Re: Air compressor electric circuit
From: Randall <randallyoung@earthlink.net>
Date: Thu, 13 Jul 2000 07:39:25 -0700
Bill :

IMO They're lying about the horsepower, so they're probably lying about
the power as well.  I'd at least go for the 20 amp circuit.

If you are running a new circuit, I'd suggest running 220v @ 25 amps or
more.  The additional cost is slight (if your main panel will handle
it), and most units can be rewired to run on it, which results in higher
efficiency, less light dimming, etc.  Besides, you might decide to get a
'real' 4.5 horsepower compressor someday, and it will require 220v.

Note : 120 volts * 15 amps = 1800 watts.  A horsepower is 747 watts. 
Even if your compressor motor was perfectly efficient, and had a power
factor of 1.0, both of which are impossible, it could only put out 2.4
hp.

And, my 2.5 hp Sanborn will pop it's 20 amp breaker on a bad day if I
don't bleed the tank before starting it the first time.  Starting
currents run way over running currents (2 or 3 times is not unusual).

Randall

"William M. Gilroy" wrote:
> 
> I am shopping for an air compress and I was wondering what kind
> of electric circuit I need to run.  If the compressor has the specs of
> 
>         4.5 HP
>         120 volt/15 amp operation
> 
> Does that mean:
>         1) The compressor needs a 15 amp circuit
>         2) The compressor draws 15 amps, and then would require a
>            20 amp circuit.
> 
> I would think it would be number one but what do other think/know.

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