Compressor outside and a switch inside?

[2Big2Ride]

I'm running EMT and planned on filling with 8 awg THHN for a future compressor (don't own a compressor today). I have changed my thinking and I'm now considering locating the compressor outside instead of inside. Whether the compressor is inside or outside I had planned on mounting a 65A disconnect commonly used for air conditioners. If I place the compressor outside I would also like a way to conveniently shut off the power from the inside where I originally planned to locate the compressor. I don't want to leave the compressor powered when the shop is not in use. What are the recommendations to shut of the power to the compressor from the inside? Perhaps another AC disconnect mounted on the inside wall also? ...yes, could switch off the circuit breaker but was looking for something located near the normal exit door where the compressor was going to be located.

 

[Charles (in GA)]

Nothing wrong with two disconnects inline. Some here will suggest schemes using relays and a whole host of other ideas. Most common probably would be a fairly light circuit, possibly 14 gauge wire even, to a standard light switch, and use this to interrupt the control circuit that runs thru the pressure switch. But you still haven't removed power from the motor starter itself if you do this, you are just preventing the pressure switch from completing the start circuit.

Charles

 

[bczygan]

Good idea.

That's what I'll do.

But just the inside switch.

Bill

 

[wyliesdiesels]

Wheres the panel located?

If inside and the compressor is outside then a disconnect is required at the compressor.

The light switch idea is often used. It will only work with compressors that have motor starters Some compressors use Hp rated pressure switches. If thats the case, u will need a horsepower rated switch. Wire the switch in-line with the pressure switch. This should be one side of the starter coil.

 

[Brian_WK]

If motor starter switching isn't feasible:
A 220v Coil contactor a fuse block and a 220V light switch. Pull one leg off each side line side of the contactor. Run to fuse block run one leg through the coil then both wires to the light switch with the proper wire colors. Turn the switch on contactor pulls in. Turn switch off contactor opens up.
Even if you can switch the motor starter fuse protect the wire running over to the switch and back as i'm assuming it will be 220V control.

Brian