Shared Neutral

[rgallahorn]

It is my understanding that any time two 110V circuits share a common neutral, the circuits should be treated as a 220V circuit (double pole breaker). Example: a 12-3 romex was pulled, one leg feeds wall outlets, one leg feeds lighting. Should these circuits be controlled by two single pole breakers or one double?
If double pole is required, does some one have a code reference?

[Larry D. Kage]

Many electricians don't think they are a good idea but I believe they are allowed if done correctly.

http://www.nachi.org/forum/f19/shared-neutrals-22893/

[Speedy Petey]

Actually most electricians think they are a good idea and use them whenever possible. I know I do.
Handle ties were not a code requirement until the new 2008 NEC. That is if your area has adopted it and the work was done after 1/1/08.

This new handle twi code is IMO a sad event, and I am afraid that we and the NEC are taking a dangerous path towards "over coding" ourselves.
There is NOTHING unsafe about MWBCs if handled properly. This new code is NOT a safety code, it is a code designed to protect unqualified people when working with electrical systems.
That friends is NOT the intent of the NEC, ie: to protect the unqualified and untrained person from themselves.

[jtedesco1]

240.20(B)(1) through (3): Revised to require identified handle ties where they are used with individual single-pole circuit breakers.

See the definition for this term, no longer will they be OK when Approved, see that definition too.

[Speedy Petey]

So then what is an identified handle tie?

[jtedesco1]

Originally Posted by Speedy Petey

So then what is an identified handle tie?

THIS NAIL WAS APPROVED


The 2002 Code permits use of a circuit breaker as a disconnect. For a multiwire branch circuit, unless limited by 210.4(B), individual single-pole circuit breakers, with or without “approved” handle ties, are permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase, line-to-neutral loads. A proposal for the 2005 NEC [ROP 10-39] was accepted to delete the word “approved” and replace it with the word “identified” because Art. 100 defines “approved” as acceptable to the authority having jurisdiction. Some electrical inspectors have accepted nails, screws, or wires as an approved handle tie. Art. 100 defines “identified” as “recognizable as suitable for the specific purpose, function, use, environment, application, and so forth, where described in a particular code requirement.” Accessories, such as handle ties, are readily available from product manufacturers.

[jtedesco1]

Here's one:

[rcooke]

Originally Posted by Speedy Petey

So then what is an identified handle tie?

A bent nail is easy to identify.
Yep sure looks like a bent nail to me .
Been working fine for many years ,must be OK my Brother-in-law the electrician put it in.
...Cookie

[Mike Whitt]

Originally Posted by jtedesco1

240.20(B)(1) through (3): Revised to require identified handle ties where they are used with individual single-pole circuit breakers.

Originally Posted by jtedesco1

See the definition for this term, no longer will they be OK when Approved, see that definition too.

Joe
This section was moved to 240.15 in the 2008 code cycle and the reference to 210.4(B) was removed.
This is what Pete was referring to. In the 2008 cycle a multiwire branch circuit will be required to open simultaneously all ungrounded conductors (210.4(B))

With the wording that is found in the 2008 code handle ties no matter if they are approved, identified or just a plain old nail will not comply.

[jtedesco1]

• Section 240.20, covering requirements for overcurrent protection in series with ungrounded conductors and requirements for operational characteristics of circuit breakers, is relocated to Part I of Article 240 in a new Section 240.15.

• These provisions are more appropriate in Part I, which covers general requirement for overcurrent devices.

• No technical changes were made in this section, just relocated text.
•

[Mike Whitt]

Yes you are right it was moved and the only text change was in (A)(3) where they added "point" so it now reads grounded neutral point.

The big change was to 210.4(B) and now reads that a multiwire circuit must simultaneously open all ungrounded (hot) conductors.