SHUNT TRIP CIRCUIT BREAKER

[jonno]

I need to specify a shunt trip circuit breaker for an elevator. The breaker will be 480v and interface with a fire alarm system to enable shutdown on machine room activation, however I understand I need 120v to activate the breaker. If the breaker is located in a 480v panel should you really be providing a 120v circuit inside this panel ? (obviously you are mixing voltages & also if the panel is shut down 120v could still remain hot)

Would it better to locate an enclosed shunt breaker remotely & provide 120v & warning labels ?

Any advice would be appreciated.

 

[iwire]

It is very common to have 120 volt shunt wiring in a 480 volt panel. You could choose to put the breaker in a separate enclosure but I would not.

 

[Jraef]

I'm not sure I understand the concern though. If you have 480V in a distribution panel and need a source of 120V for a ST, where is that 120V going to come from, a different building? Because if your concern is that when you kill the 480V to the panel in order to work on exposed bus bars after removing the dead front, and the 120V comes (even indirectly via a lighting transformer) from any one of the 480V feeders in that panel, problem solved. If not, it's not like a distribution panel is something that people enter on a regular basis, so just put in some very clear and prominent sings warning anyone who MIGHT remove the dead front that there is a foreign source of 120V.

 

[jonno]

Guys, many thanks for the responses.