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electrifier
electrifier, Master Electrician
Category: Electrical
Satisfied Customers: 1633
Experience:  Electrical contractor and electrical inspector for over 24 years with phone and networking expertise
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Hi, I am wiring a 220v exhaust fan for a paint booth and have

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Hi, I am wiring a 220v exhaust fan for a paint booth and have it done up to the on/off switch but am confused as to how to wire in the two door safety switches that only work when door is shut. The switches only have 3 wires, do I need to run separate wires to each or can they be wired in series? thanks a bunch

electrifier :

How do you want it to work? Do you want it to turn off when either door is open? Is this for spray painting? Do you know how to turn off the air when the exhaust is not working?

electrifier :

Each switch has a common and a NC and NO contact.

electrifier :

Do you have a solenoid valve on the air line?

electrifier :

Do you only want the fan to turn off when either door is open?

Customer:

Yes I want it to turn off when door is open. yes for spray painting. to turn off the air wont it be wired the same as for these switches? yes there is a solenoid on the air line. with a common, NC, NO contact don't you run a 110 leg to each side (red,blk) yes when door is open but shut off with on/off toggle switch when not in use

electrifier :

For this you must wire in series to the motor contactor control circuit. Use the common and NO terminals so when the doors are closed the switch will close, so both doors will be closed to make the motor run.

electrifier :

Do you have a starter to control the motor?

Customer:

contactor motor not mag start

electrifier :

Use an aux contact on the starter to control the solenoid valve, when the starter is on the air valve is on.

electrifier :

Do you have an aux contact on the contactor?

electrifier :

How big is the motor?

Customer:

ok is there a schematic somewhere to follow? motor is 2hp

electrifier :

Do you have some type of overload protection on the motor?

Customer:

yes there is a reset button

electrifier :

So you could have power to the motor and it would need to be reset. This makes it hard to control the valve.

electrifier :

Take one leg off the contactor to the solenoid valve to turn on the air when the motor is running. The reset button on the motor could be a big problem for you. Using a starter and overloads instead of the internal protection would be a better bet. I would not approve this installation if I was inspecting it. It is not designed to be fail safe

electrifier :

Have you talked to your mechanical inspector about this installation?

Customer:

not yet

electrifier :

I would advise it before you go any further so you don't do something you have to change

electrifier :

I would hate to see you have problems

electrifier :

Are you the electrician wiring the booth?

Customer:

ok I will do that and thanks for the input

Customer:

yes I am

electrifier :

I want you to be successful on your first try

Customer:

MEEEEE TOOOOOOOOOO

electrifier :

Ok, cool. Come back here after you talk to inspectors. I will then help you succeed,.

electrifier :

Your success is my goal

Customer:

thanks again

electrifier :

I have to sleep now. Talk to you soon.

electrifier and other Electrical Specialists are ready to help you

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