Lock On

[Pat Weldon]

Can a circuit breaker that supplies power to a Fire Alarm and Fire suppresion system be locked on? Molded case breaker will trip due to overcurrent. :-?

 

[480sparky]

It's usually required. The breaker will trip if need be, but you cannot turn it off manually.

 

[iwire]

Yes you can lock breaker handles on, the NEC even requires that for circuits supplying only EBUs.

As 480 mentioned it does not keep it from tripping.

 

[Pat Weldon]

Can you tell me in what article in the NEC I can find that ? Thank you very much for your time.

 

[charlie]

. . . what article in the NEC I can find that?

695.4(B)(2)(2) is a good place to start. Additionally, circuit breakers are to be trip free (240.80 and means that it can be locked in the closed position and still open in the case of overcurrent. Lastly, if there is no place that says you can't lock it, then you can lock it. This is a permissive Code. :smile:

 

[LarryFine]

Yes you can lock breaker handles on, the NEC even requires that for circuits supplying only EBUs.

As 480 mentioned it does not keep it from tripping.

Funny, I just installed a handle-lock on a breaker this morning for a fire-panel supply circuit I installed yesterday.

How far back have breakers had the free-trip requirement? What if the breaker that must be locked on is not of the free-trip design?

This is a GE type TEB breaker, by the way. The lock is a TLD3.

 

[jim dungar]

How far back have breakers had the free-trip requirement? What if the breaker that must be locked on is not of the free-trip design?

Square D's QO has been trip free since it was introduced in the late 50's.

I remember this topic being discussed when I started in the trade over 30yrs ago.