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Run fire alarm control wires to an enclosed MCCB to power shunt trip coil?

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Mccalabrese

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Location
Seattle
Occupation
Gear Quotations (Union journeyman but working for distributer currently)
Can I used an enclosed circuit breaker with an aux shunt trip or would it need to be in a panel? I'm under the impression that this would be fine but I just wanted to verify with the pros before I send it out.
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Mccalabrese said:
Can I used an enclosed circuit breaker with an aux shunt trip or would it need to be in a panel? I'm under the impression that this would be fine but I just wanted to verify with the pros before I send it out.
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I'm not sure exactly what you are proposing, but connections are made all the time between fire alarm relay modules and foreign systems. Shunt trips for elevators comes directly to mind. Sometimes there is a bit of a tussle regarding what kind of wire should go from the relay to the CB. Some people insist it should be "fire alarm" wire, others are looking for control cable or some other item. I think THHN/THWN is fine.
 
M

Mccalabrese

Member
Location
Seattle
Occupation
Gear Quotations (Union journeyman but working for distributer currently)
gadfly56 said:
I'm not sure exactly what you are proposing, but connections are made all the time between fire alarm relay modules and foreign systems. Shunt trips for elevators comes directly to mind. Sometimes there is a bit of a tussle regarding what kind of wire should go from the relay to the CB. Some people insist it should be "fire alarm" wire, others are looking for control cable or some other item. I think THHN/THWN is fine.
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Thanks for your reply, I am more just attempting to make sure that there is no code against running low loot control wires into an individual enclosed CB as opposed to a panel. I don’t see why there would be but the question came up and I felt it better to be safe than sorry
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Several things, what is the voltage of your shunt trip coil? What is the voltage rating of the fire alarm cable? Keep in mind if you use a low voltage shuntrip, will the fire alarm relay have the capacity for the high current? Just got through re-designing the controls for a 24 volt shunt trip that has a 38 amp draw. Fire alarm relay had only a 1/2 amp contact, so they were smoking it every time it was tested. At least they had the right size transformer.
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
hillbilly1 said:
Several things, what is the voltage of your shunt trip coil? What is the voltage rating of the fire alarm cable? Keep in mind if you use a low voltage shuntrip, will the fire alarm relay have the capacity for the high current? Just got through re-designing the controls for a 24 volt shunt trip that has a 38 amp draw. Fire alarm relay had only a 1/2 amp contact, so they were smoking it every time it was tested. At least they had the right size transformer.
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Geez, 38 amps? What are you shunting, Grand Coulee Dam? You need like a 40 or 50 amp definite purpose contactor for that. A RIB wouldn't cut it. The whole of the new LaGuardia Terminal B doesn't have anything in it requiring that level of current to operate any of the shunts they have.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
gadfly56 said:
Geez, 38 amps? What are you shunting, Grand Coulee Dam? You need like a 40 or 50 amp definite purpose contactor for that. A RIB wouldn't cut it. The whole of the new LaGuardia Terminal B doesn't have anything in it requiring that level of current to operate any of the shunts they have.
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Yep, that’s what I redesigned the control circuit for. I knew 24 volt would be higher (don’t know why they specified 24) but I was surprised too when I pulled the spec. I figured 10 to 20. Most people use 120 volt coils, much lower current! Only a 150 amp breaker!
 
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