I've went in the "search" menu and found some great information on "shunt trip breakers". I have a job where I will not be able to add any shunt trip breakers because the panel is packed and I know a shunt trip breaker requires another space, so I'm thinking about going just above the panel and setting a traugh and installing contactors inside the traugh to control the other circuits that need to go off when the Ansul system calls for it. Since the shunt trip breakers require 120 volts to activate it, will I not have to run another wire to the NC contact on the ansul system to energize the coils on my contactors, so that when the ansul system is activated, the coils will "drop out" on the circuits I have installed the contactors on? I was originally thinking I could come off the same wire that the other "shunt breakers" were on, but if they need the presence of 120 volts to trip, then I need the absence of 120 volts to make my contactors drop out. Thanks for the help. Steve...

Shunts need the voltage to open.Use a mechanical contactor N/C (like a lighting contactor).Or go back to the distribution panel and add a Main ST breaker.

Remember, what ever you use it MUST need to be manually reset.

NFPA 17A
4.4.3.7: Shut off devices shall require manual resetting prior to fuel or power being restored.

Lee, I think you are misreading the NFPA 17A and 95 requirements.

Either a contactor or a shunt trip breaker will be "manually reset" when the release mechanism is reset. That's just fine.

What is NOT allowed is for that resetting operation to also open up gas flow to the appliances - unless those appliances also have electric automatic spark igniters. The manual reset provision is there to help ensure that the (presumably still 'on') appliances don't fill the kitchen with gas fumes.

Since most Ansul systems use a mechanical gas valve, rather than an solenoid operated one, this is usually not an issue.

Reno_ "Since most"-

Not all.

This I will concede as interpretation.

Perhaps I read too deep.
However,A shunt trip IS a shut off device.

lets assume (I know we should not) All appliances are electric.

Being affiliated in the industry,I will not and do not reset anything aside from 'My' equipment. If I reset and move along,Now the gas stove or electric stove (insert appliance here) Is re energized after my system is reset,Not recharged.
A new or current hazard re emerges.

Not all kitchen fires stem from a cooking situation.

NFPA 17 and 17A require a reset relay if the gas valve is electrical. As do the manufacturers, Ansul, Amerex and Badger. Even if the appliances to have electric spark igniters, they could always be replaced later with standing pilot appliances.

I agree as to resetting the gas valve, if the gas valve is electric. Now, I cannot speak for the entire world ... but in my experience, electric valves are few and far between.

Absent such a valve, there is no need for anything special - it all - gas and power - gets reset when the trigger mechanism is reset. That's all you need.

As for the difference in resetting a shunt trip vs. resetting a contactor .... it is true that a shunt trip will require a second step to restore power. Not only must the trigger mechanism be reset, the breaker must also be reset. Which method you use is purely a design choice; I can point to situations that favor each.

As I read the original post you already have some shunt trip breakers in the panel, I am assuming they are on the same system you need to ad the contactors to.

Why not power the contactor coils off the existing load side of the shunt trip breaker. The Ansul trips the shunt trip and the shunt trip drops the contactor for the other loads.

A master shut trip that controls a slew of contactors is the way it's done for all of the Safeways I've built.

Field engineering our own schemes was never permitted.

So I never had to worry about other ways to do it.