I am hooking up a new air compressor. 5 hp and 10 feet from the breaker box. what size wire and breaker should I get?

by John
(Mo)

I have a new air compressor. It is 5 hp and 10 feet from the breaker box. I will use 220.I need to know the size of breaker to buy and what guage of wire.


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Bill says...

John, the motor plate will tell you the amp draw of the motor (or the manual). Make sure the breaker is more than the draw.

Your local big box lumber store will likely have a chart in the electrical department that will relate amperage over distance to help you select the right gauge.

You need to know the amp draw to figure out the wire size. However, bigger wire is always better than smaller, so if you are only running 10 feet, if I were installing it, I'd probably go 8 gauge.

Cheers,

Bill


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Fuse blows on shut down

by frank
(illinois)

Last week a couple days when turning off a three phase 480v compressor one of the fuses blew. Today when turning on one of the fuses blew in half. What could be the problem.

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Bill says...

Frank, I've moved this to electrical-troubleshooting as I expect that's what the issue is. I hope that we have a friendly electrician out there that reads this and posts a comment.

If it were blowing breakers on high pressure cut out, I'd be thinking the pressure switch.

Since I understand that the compressor blows breakers on shut down (as in you are turning off the power ) I think it's an electrical issue.

Cheers,

Bill

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Old Joy 30 Hp....need wiring diagram please

Hi,

I have an old Joy 30 Hp 3 phase compressor (Model TA-30BAN4B Serial 7401M). The last electrician took the wiring out and now I am trying to figure out how to wire it up. Does anyone have a wiring diagram?

I know how to wire it to run in the off/on mode, but I am trying to figure out how to let the electric motor continuously run and have the load/unload circuit work.

The wiring basically consists of:
1) Solenoid pumping oil that has to be on 100% of the time
2) Contactor
2) Tank pressure switch
3) Loader/unloader pressure switch (not sure of the name)
4) Loader/unloader solenoid
5) 3 position switch on/off/on. (sort of like 2 spst switches that can only be operated one at a time).

Any help is greatly appreciated. I have been scratching my head for a week now.

Tim







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