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Compressor Wiring

Ramper

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I have read just about ALL threads regarding wiring a 240V (220V) compressor, but I still have questions. I have 100AMP service in my shop. There is a 60AMP 240V circuit breaker fromk the previous owner, but no wires connected to it. I am thinking I would run a circuit to a plu and then run a plug on the compressor (just in case I need to move it)

My questions:
  • What size breaker?
  • What type of outlet?
  • What type of plug?
I do not have and may never have any other 240V tools

Here are some pics
 

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Ramper

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it is a 5HP. If I read the tag correctly it is 24AMP. It is a VINTAGE unit so it is really 5hp
 

5lima30

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I ran 10-2 with a 30 amp breaker and went with a 6-30R outlet. My 5hp 60 gal compressor requires about 23 amps as I recall. I installed a matching 6-30P plug pigtail off the compressor. It works great for me.
 

pattenp

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If it's 24A then 30A breaker, outlet and plug as 5lima30 posted will do.

NEMA_6-30P.jpg
NEMA_6-30R.jpg
 
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Ramper

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So just to be sure:
30 AMP Double Breaker
10-2 Romex to a 6-30R oulet (would 8-2 be better?)
Then a pigtail cord with a 6-30R end to the compressor.
 
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pattenp

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You got it. Except 8-2 is not better, unless you need to step it up to a 40A circuit in the future, or compensate for voltage drop on a long run.

So just to be sure:
30 AMP Double Breaker
10-2 Romex to a 6-30R oulet (would 8-2 be better?)
Then a pigtail cord with a 6-30R end to the compressor.
 
Last edited:

Gary S

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I ran 10-2 with a 30 amp breaker and went with a 6-30R outlet. My 5hp 60 gal compressor requires about 23 amps as I recall. I installed a matching 6-30P plug pigtail off the compressor. It works great for me.

Mine is wired similarly. I used 8-2 and a 30 amp breaker hardwired into the breaker in the box. I didn't want a plug to complicate the wiring. With #8 wire, the motor seems to spin up faster and easier than with #10.
I did the same thing with my little 120v compressor. When I had it wired with #12 on a 20A breaker, it would trip the breaker trying to startup when the garage was cold. Switching the wire from #12 to #10 gave me fast starts so the 20A breaker no longer trips in the cold.
 
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Ramper

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After reading more thread I am thinking a disconect with an indicator light. So 8-3 (two hots a neutral and a ground) from the breaker box to the disconect and then 8-2 to the compressor.
 

pattenp

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Make sure the 6-30 plug and outlet will handle #8. Are you going to use #8 SO cord from the compressor to the disconnect?
 
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Ramper

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I want to do this once and do it right. I will be "researching" this for a few days on GJ. I really like the set ups with the indicator lights.
 

Fred43

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Bellingham, MA
Ramper,
I have 47 years of Elec Contracting experience

I definately would install a motor stater before the receptacle.
The Motor heaters in the starter will protect your motor if it overheats for any reason and there are many ways it can overheat.
It is required by code.
There are insurance liabilities if the motor caught fire and it spreads
It also gives you the presure switch automatic start and stop features.
 
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