Multiwire branch

[jcarter052496]

Best Design Practice

Best Design Practice

For typical 20A/1P circuits, we show 4 circuits per homerun (4 hots, 2 neutrals, 6 current carrying conductors per code) fed from 20A/1P circuit breakers.

Per NEC 2008 210.4B, we are going to change to 3 circuits per homerun and add a note to provide 3-pole handle ties.

This tie will allow a single pole breaker to trip and be reset without affecting it's adjacent, tied breaker, right?

Also, I assume this is the best design practice, but would like comments.

Another option is to ONLY allow single pole homeruns (imagine 42 MC or AC cables coming out of 1 panel, yuck!).

Or show 3-pole breakers where 1 short or overcurrent event will affect 6 offices, instead of 2 offices. This would be unacceptable to my clients.

Again, any comments would be appreciated.

 

[iwire]

This tie will allow a single pole breaker to trip and be reset without affecting it's adjacent, tied breaker, right?

With handle ties one trip may not take out the one beside it but it can.

With a common trip it is of course a guarantee.

Unfortunately because of the new NEC rule the best design may be to use all 2 wire circuits.

 

[Smart $]

This tie will allow a single pole breaker to trip and be reset without affecting it's adjacent, tied breaker, right?

NOT.

Provided it hasn't affected it already, resetting the tripped breaker requires its handle to be flipped all the way to the OFF position. Unless you remove the handle tie prior to this action and replace afterwards rolleyes, it will affect the adjacent, handle-tied breaker.

 

[Karl H]

So your saying a screw or piece of wire inserted through the
holes of two single pole breaker handles arent "Approved Handle Ties?"

 

[bjp_ne_elec]

Does anyone have a pic of these handle ties? Do they make a version for a Crouse Hinds panel?

Also, what if you're pulling off an exisiting two wire with shared neutral? I have a case where the two wire circuit is already run out of the panel in to an existing JB just above the panel in the ceiling. As it's existing, and I'm just picking up and running from there - would I have to correct the existing install?

Thanks

 

[jrock0305]

thats common sense for all the neutral sharers out there who dont label or use a common trip breaker how would you like to shut a ckt off and take the neutral hit from 2 other ckts without warning because someone just dosent care about the next guy