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Discussion Starter · #1 ·
Hello all,
I have a small commercial job I am finishing, (my first restaurant), and I would like some advice about the fire suppression system. Here is what I have:

2 exhaust fans & a MUA unit, all powered via contactors (motor starters).

Simplex G. is doing the under the hood fire system and they have installed pyro-chem microswitches.
The microswitches have 3 wires:
Red/Hot
Black/N.O.
Brown/N.C.

The paper work for the microswitches says they can handle 21A 120v, so it does not look like a need a relay for this model.

My question is about the micro switches, if I run a 120v control circuit to the switches, am i supposed to run a wire from the black/N.O. to the normally open terminal on my contactor. (I want the exhaust to kick on or continue running when the fire system is activated).

I just want to make sure method is correct. I am worried about the 120v from the microswitch causing a short on the contactors, as the power would be from a different phase than the contactor control circuit.
 

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When I had that setup a few times in the past I ran my 120v power for the MUA unit controls through the common and NC contacts on the micro switch.
Then that same power I ran through a NO dry set of contacts on a RIB relay ( power went to the common and the other went to the NO contact on the micro switch).
The inter lock relay or air proving switch turned on the RIB coil.
Then off the same NO contact on the micro switch I hit the exhaust fan coil or starter.
So basically when they pull the cord for the micro switch it goes to NO contacts and feeds the exhaust coil, your control power gets killed because it was ran through NC on micro, your 120 control power is ran through NO contacts on the Rib so that cannot back feed.

Now I don't have to create my own system anymore because most of them come with everything already set up for ansul shutdown in a control panel.



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Discussion Starter · #3 ·
First of all, Thanks for your time,

My issue is with the control circuit being 240v (coil voltage is 240v). Am I allowed to break one phase via the micro switch and leave the other connected, even during alarm activation?
 

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Oh in your post you said 120v.
Anyway I don't see a problem with that.
The fire alarm guy will use one of those micro switches for the alarm.
Has nothing to do with your chit.


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