shunt trip wiring

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Mes,AZ
Have a square D 30amp single pole shunt breaker, wonder were the controll wire from the ansul system goes on the breaker. On the shunt side there are two screws, is one fore control and one for the equipment neutral? And how do I now if if its N.O or N.C?
Here is what is says on the breaker; "shunt trip circuit is ope when circuit breaker is off or tripped" thanks in advance!
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
A shunt-trip on a breaker is just a breaker that contains a remote-control way of tripping it. Sending 120v to the coil trips it, and then it must be manually reset when the emergency is over.

That last part means that there's a contact in series with the trip coil, so leaving the tripping circuit energized won't burn out the coil. If the breaker was supplying its own tripping power, it wouldn't matter anyway.

The terminals should be labeled, and many such breakers have wires rather than screws. The two terminals (other than the load) are for the tripping coil. One ties to the panel's neutral bus, and the other from the Ansul.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired) DINOSAUR
If I may, one small side note to Larry's excellent explanation. Shunt trip coils are available in voltages other than 120v, so to be on the safe side make sure your operating voltage matches the trip.
(120v is, I imagine, by far the most common, but there are others including lv DC coils for use with fire alarm circuits.
 

TOOL_5150

Senior Member
Location
bay area, ca
just a quick question about this... Lets say there is a shunt trip breaker in a panel that has no power.. but the shunt circuit does have power... can that breaker still be tripped?

~Matt
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
just a quick question about this... Lets say there is a shunt trip breaker in a panel that has no power.. but the shunt circuit does have power... can that breaker still be tripped?
Yes. There's a solenoid (electromagnet) in the breaker that releases the latch mechanism. That circuit is independent of the breaker's load-carrying parts.
 
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