Multi-wire Branch Circuits

[kwired]

Is it possible if one does trip and the other does not with a handle tie on it?

With the four remaining players we have today Square D, Eaton, Siemens, and GE and the product lines those four have acquired in the past 40 years, when one trips it won't have enough force to pull others with handles tied to it into the off position.

However in order to reset the one that has tripped you likely will end up turning the non tripped one(s) off in the process.

There may be some old obsolete breakers out there that can do so.

 

[infinity]

With the four remaining players we have today Square D, Eaton, Siemens, and GE and the product lines those four have acquired in the past 40 years, when one trips it won't have enough force to pull others with handles tied to it into the off position.

Some breaker handles seem to be very sensitive. I find that with my big fingers trying to shut of one side of a twin breaker I can easily touch the adjacent breaker handle. Even a light touch seems to make the thing pop. For a 3 single pole CB's handle tied together I would guess that the center CB tripping may have a chance at tripping one or two of the other CB's. I wonder if someone ever tested this.

 

[ptonsparky]

I did a few homes early on and every one of them had MWBC. Every commercial job had them. The breakers may or may not have been adjacent after the initial construction.

 

[kwired]

Some breaker handles seem to be very sensitive. I find that with my big fingers trying to shut of one side of a twin breaker I can easily touch the adjacent breaker handle. Even a light touch seems to make the thing pop. For a 3 single pole CB's handle tied together I would guess that the center CB tripping may have a chance at tripping one or two of the other CB's. I wonder if someone ever tested this.

I've had many unintentional "shut off's" as well. Can't really recall any trips of a single pole taking out others that are handle tied to it though. Always had to shut the others off to reset the tripped one.

The Cutler Hammer (CH series) may be the exception. I don't get around these all that often though when I first started in this trade it was mostly what we used. The fact the handles don't trip to a mid position may tend to have more of a chance to pull adjacent tied handles to off position.

 

[ramsy]

With the four remaining players we have today Square D, Eaton, Siemens, and GE..

Leviton is a new kid in town, with no handle ties or twins.

 

[jaggedben]

For as long as I remember, breakers have been required to have "trip free" operation, meaning that the breaker must open when the load conditions require it, even when the operating handle is forced to stay in the ON position.
Two adjacent breakers which are not part of a common assembly will not implement a "common trip" condition where both open if one senses a a fault, even if they are connected by a handle tie. The common trip function cannot be implemented by something external to the breaker(s).

I've seen a handle tie turn off the other handle when one handle trips. But it's certainly not to be counted upon.