# INTERLOCKING Exhaust Fan and MUA



## Wirenuting (Sep 12, 2010)

Parallel the CO's dry contact output to the coil of each relay coil. 

If you need starter feed back, use an aux contact on the starter.


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## macmikeman (Jan 23, 2007)

Plug in relays have two sets of nc and two sets of no contacts. You can interlock by putting the coils of each of the motor starters thru the other relay's spare set of NO contacts, that way if one motor drops out, the other will also.


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## power (Feb 27, 2012)

@WireNutting - Thanks for that....your comment might be the same as the following post

@McMikeMan - That sounds good, but try to draw it out. That will work when both MUA and EF have already started, but they could never start from very beginning. Each unit locks out the other!


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## macmikeman (Jan 23, 2007)

power said:


> @WireNutting - Thanks for that....your comment might be the same as the following post
> 
> @McMikeMan - That sounds good, but try to draw it out. That will work when both MUA and EF have already started, but they could never start from very beginning. Each unit locks out the other!


Bada bing! but I didn't think about that till .oooooo5 microseconds after I hit the post button...............................:laughing:


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## power (Feb 27, 2012)

It's a tricky one, I know!

Until I took the time to draw out it, I thought it was easy. It seems it isn't.


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## macmikeman (Jan 23, 2007)

Still without drawing it out or thinking it thru my next suggestion is perhaps a timing relay in the mix to deal with starting up the first fan and holding it till #2 is turned on so the original macsolution works..........


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## power (Feb 27, 2012)

@macmikeman = I think you are bang on right. That's what I doing right now.


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## Nom Deplume (Jul 21, 2013)

Stop with the @. This isn't tweeter.


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