SET SCREW ON CB

[AARON-EE]

HI, Doe anyone know what the set screws on these breakers are for? Thank you

 

[infinity]

Those are breaker locks used to keep someone from inadvertently shutting off the CB. They're required on certain circuits like those in 700.12(F)(2)Exception, et al.

Welcome to the Forum.

 

[mwm1752]

non compliant with 110.25 -- what does the panel schedule say?

 

[infinity]

non compliant with 110.25 -- what does the panel schedule say?

My guess it that the CB's are not being used as a disconnecting means.

 

[petersonra]

non compliant with 110.25 -- what does the panel schedule say?

That paragraph refers to locking things in the open position. These set screws lock them in the closed position.

 

[Jraef]

That paragraph refers to locking things in the open position. These set screws lock them in the closed position.

Correct and keep in mind that just because it is locked closed, doesn't meant it can't trip, it can and will, but the requires someone to unscrew the lock to reset it. So that's another reason why some people use them, to keep casual users from continually resetting breakers.

 

[AARON-EE]

THANK YOU FOR THE INSGHT.

THANK YOU FOR THE INSGHT.

Thank you for the input everyone. They are on various loads I could see the tenant would not want inadvertently shut off.

 

[mwm1752]

That paragraph refers to locking things in the open position. These set screws lock them in the closed position.

So we should call these lock ons :?

 

[infinity]

So we should call these lock ons :?

I would, the NEC uses the words lock-on feature.

700.12(F)(2)Exception: In a separate and uninterrupted area supplied
by a minimum of three normal lighting circuits that are not
part of a multiwire branch circuit, a separate branch circuit
for unit equipment shall be permitted if it originates from
the same panelboard as that of the normal lighting circuits
and is provided with a lock-on feature.

 

[sliderule]

Often called a lock dog.

 

[JDB3]

Use them for circuit feeding fire alarm panel

 

[GoldDigger]

Use them for circuit feeding fire alarm panel

And often for circuits with mechanical time clocks. As well as circuits for egress lighting and night lighting.