Wiring compressor
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From: Hampstead, NC
Wiring compressor
I recently bought a Sanborn compressor (230 volt/15 amp motor) and am wanting to get it wired up and working in the next couple of days. I am wondering if I need any more than a 20 amp circuit for this compressor. It has, as mentioned before, a 230 volt/15 amp motor on it. I have a 4 foot length of 10/3 extension cord wire for the pressure switch to wall socket. I also have 50 feet of 10/2 with ground wire for the run from circuit breaker to outlet. The run is about 35 feet, if that is important. This circuit is for the compressor only, nothing else will ever be run off of it.
Tuned
Joined: Sep 2003
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Everything you have will work, use a 30A breaker on it. The startup currents are high and the 30 keeps it from tripping. What you are doing is a common compressor circuit. If you are wiring this to a 4 wire subfed panel remember to put ground to ground bar, if it is a main service entrance you can go to a ground bar if it has one or to the neutral bar. Also make sure you are using a 30A rated plug/receptical.
Senior User
Joined: Feb 2002
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I have the same unit, and that hookup will serve well. Another thought to consider when wiring, is adding a time switch to prevent it starting up in the wee hours of the morning when everyone's asleep. I used an Intermatic T-104 that I got on ebay for about $20.00
Post Fiend
Joined: Jun 2001
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From: Running Springs CA
30A rated breaker and fittings is overkill in this application, 20A is fine.
1. Circuit breakers are designed to absorb short overloads, as in motor starting. Fuses blow instantaneously.
2. Air compressors have, or should have, a compression release valve that lets it start turning before appling load.
3. Instead of a long extension cord, I use air hose instead.
Jim
1. Circuit breakers are designed to absorb short overloads, as in motor starting. Fuses blow instantaneously.
2. Air compressors have, or should have, a compression release valve that lets it start turning before appling load.
3. Instead of a long extension cord, I use air hose instead.
Jim
Tuned
Joined: Sep 2003
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You are correct, a 20 would more than likely work fine but I have seen some of these pesky buggers trip them on start, not all the time but on occassion, my bud had one that about every 6th start it did it. Fuses work if they are slo-blow. The reason we sometimes run 30A on these is that the motor has its own thermal protection, it has a thermal reseting feature on it that protects the wire, the breakers main function is short circuit interuption and as a means of disconnect. With its own thermal you could run 12 wire and a 30 breaker or super lag fuse. The wire needs to be 125% of the FLA to allow it to be over breakered. A 12 is good for 20, the load is 15, could breaker it to a 30.
Last edited by Sberry27; Dec 24, 2004 at 12:58 AM.
Posting Guru
Joined: Mar 2004
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From: MI
Originally Posted by jimandmandy
30A rated breaker and fittings is overkill in this application, 20A is fine.
the fact that this a motor load that could be running all day(continuous load), you size the cicut to 125% of the load(125% of 15 = 18.75), and code states you can only load a continuous circut to 80%. 80% of 20 = 16 80% of 30 = 27.
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