correctly wire fire suppression without use of shunt breakers

Little Bill

Staff member
Tennessee NEC:2017
For some reason I can't get my diagram to post, it says there is too many characters.:rant:

But I just wired a Amerex fire suppression system a few weeks ago. I will post the steps and you can draw it out if you like.

I used 2 separate contactors in 2 separate junction boxes. I did this because another piece of equipment was sprung on me at the last minute and I already had one box up. I don't know what equipment you have, and that would determine how many contactors you need.

I used a nipple to come out of the control head with the leads from the micro switch into a small box to make the connections since you're not allowed to make splices in the control head.
I was controlling two pieces of equipment along with the make-up air and exhaust. The two fans (MUA & Exhaust) were controlled by a single switch. I wired them so the MUA would go off and the exhaust would stay on regardless of the switch's position.

The connections went like this:

Hot to N/O of the micro switch and to the line side of the fan switch

Load side of switch to Common of micro switch and to exhaust fan

N/C from micro switch to MUA and to the coils of the two contactors
the coils were both 120V line voltage

Now you might have more than one micro switch and more/other equipment, but this should point you in the right direction.