fire suppression system

Status
Not open for further replies.
Well I wired my first commercial fire suppression system and I have an inspection tomorrow. Here is what I did and you knowledged folks tell me if I should be worried. I have a 220 V exhaust, 120V Make up air and 120V hood lights. I got 3 NO contactors, 1 NO micro switch, 1NC micro switch, and a common. So I ran a 120v control circuit to a Two pole switch that switches the exh and mua, the mua runs to the single NO micro switch and from there to the NO contactor. The ex runs straight from the 2 pole switch to the contactor. I have a single pole switch for the hood lights and the same 120V control circuit powers it , then runs to the same micro switch NO (there is only one NO micro switch) which then goes to the contactor. I can't seem to understand how when the system is activated, it will shut down lights, mua, but leave the exh running. Any insight would be greatly appreciated. Thank you.
 

Riograndeelectric

Senior Member
Well I wired my first commercial fire suppression system and I have an inspection tomorrow. Here is what I did and you knowledged folks tell me if I should be worried. I have a 220 V exhaust, 120V Make up air and 120V hood lights. I got 3 NO contactors, 1 NO micro switch, 1NC micro switch, and a common. So I ran a 120v control circuit to a Two pole switch that switches the exh and mua, the mua runs to the single NO micro switch and from there to the NO contactor. The ex runs straight from the 2 pole switch to the contactor. I have a single pole switch for the hood lights and the same 120V control circuit powers it , then runs to the same micro switch NO (there is only one NO micro switch) which then goes to the contactor. I can't seem to understand how when the system is activated, it will shut down lights, mua, but leave the exh running. Any insight would be greatly appreciated. Thank you.


you did not mention what other electrically operated appliances you have under the hood. the suppression system must shut down all Electrical for all appliance's located under the hood and the natural gas .

why did you have to install the micro switches? these should be part of the suppression system


I use a 6 pin ice cube relay 120 Volt coil. the ice cube controls all of the contactors for the Hood system
I put the Make up air on it own 1 or 2 pole contactor.

I use the NC contacts on micoswitch to power the ice cube realy then in turn feed the contactors of f the NC side of ice cube realy. i Put a jumper wire from the the common terminal to the NO contacts of the ice cube relay.

when the suppression system trips it shuts power off to the ice cube relay but the NO contacts of the ice cube relay close upon power loss thus feeding power to the Make up air


I am not a fan of shunt trip breakers>
 

renosteinke

Senior Member
Location
NE Arkansas
Let NFPA 96 (Commercial Kitchen Exhaust Hoods) be your guide. I think that's the name - double check. It's an understatement to say that very few folks have read, or even own, this standard. There are a lot of assertions made that are NOT supported by the code- especially regarding make-up air.

Here are some of the 'pitfalls' that may, or may not, become issues:

The fire suppression usually has room for three micro-switches, and the guy usually installs two. One is used by the alarm company, and one by you. The switches have an NO, NC, and common contact.

If there is no alarm system, you will have to hook up an alarm bell or light.

I typically use a definite purpose contactor, with as many contacts as I need. I have had to use more than one, to get the required number of contacts.

I will typically use a pull can for mounting the contactors, but I have hear of inspectors who want the box to have a hinged cover.

One 'devil' in the details regards gas-fired cooking equipment. IF the equipment has pilot lights, you will also have to instal a separate 'reset' for the gas line solenoid valve.

Typically everything under the hood must be shut down - every source of power or fuel.
 
Status
Not open for further replies.
Top