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Air Compressor Pressure Switch Help.

csmitty

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Joined
Dec 17, 2010
Messages
1,542
So, I've done a ton of reading and mostly have my game plan down. however, I'm a bit stuck on pressure switch wiring.

I have a 230V 7.5hp single phase motor. 240V 7.5hp 40A magnetic starter with 240V control circuit. The pressure switch I'm looking at takes 240V but I'm wondering how many amps will go through the control circuit when the pressure switch kicks in and what size wire I need to run between the two. I can only assume it will be minimal amps but I just can't seem to verify it on any of the data sheets. Whats they typical install for the PS?

Thanks.
 
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larry_g

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oregon
It is minimal as said above however the coil current should be listed on the starter.

lg
no neat sig line
 
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wyliesdiesels

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Aug 14, 2012
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20,279
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Modesto, CA
Should only be the current of the starter coul which like everyone else has said is minimal.

And to simplify things u really don't need to run both legs through the PS. Just run one leg through it and back to the starter coil. The other side of the coil will be powered through the overload relay.
 
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csmitty

Well-known member
Joined
Dec 17, 2010
Messages
1,542
True, it was just rated up to 10A at 240. Which would be just using it to start the motor. I was planning on just running one leg to it. Just the engineer in me was missing some numbers. I'll check the starter when I get home though. The data sheet online doesn't say much. Its a Square D 8911DPSG42V09.

If it doesn't give me anything I'll just run some 12ga.
 
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