Multi-wire circuits

[Robert E Lee]

My son-in-law in is the process of installing a generator backup system at their home. There are (4) multi-wire circuits that he plans on moving over to the transfer panel. When he went for the permit today he was told that he will need to use "handle ties" on the breakers of these multi-wire circuits. I have never been aware of the need for "handle ties" on multi-wire circuits other than on the disposal/dishwasher outlet. They are located in WA state, in a suburb of Seattle, anyone else ever run into something like this?

[John Dirks Jr]

I've only seen handle ties for a multi wire circuit once in five years of inspecting. As you said Robert, it was for a dishwasher/disposal combination on a 2010 new home construction. Since that time I've done other new homes and never saw the ties again.

[Brandon Whitmore]

210.4 Multiwire Branch Circuits.

(A) General. Branch circuits recognized by this article

shall be permitted as multiwire circuits. A multiwire circuit

shall be permitted to be considered as multiple circuits. All

conductors of a multiwire branch circuit shall originate

from the same panelboard or similar distribution equip-

ment.

FPN: A 3-phase, 4-wire, wye-connected power system

used to supply power to nonlinear loads may necessitate

that the power system design allow for the possibility of

high harmonic currents on the neutral conductor.

(B) Disconnecting Means. Each multiwire branch circuit

shall be provided with a means that will simultaneously

disconnect all ungrounded conductors at the point where

the branch circuit originates.

© Line-to-Neutral Loads. Multiwire branch circuits

shall supply only line-to-neutral loads.

Exception No. 1: A multiwire branch circuit that supplies

only one utilization equipment.

Exception No. 2: Where all ungrounded conductors of the

multiwire branch circuit are opened simultaneously by the

branch-circuit overcurrent device.

FPN: See 300.13(B) for continuity of grounded conductor

on multiwire circuits.

(D) Grouping. The ungrounded and grounded conductors

of each multiwire branch circuit shall be grouped by wire

ties or similar means in at least one location within the

panelboard or other point of origination.

Exception: The requirement for grouping shall not apply if

the circuit enters from a cable or raceway unique to the

circuit that makes the grouping obvious.

[Robert E Lee]

(B) Disconnecting Means. Each multiwire branch circuit

shall be provided with a means that will simultaneously

disconnect all ungrounded conductors at the point where

the branch circuit originates.

Brandon, what version of the NEC is the para from? As almost all of the circuits in their existing panel are multi-wire circuits and none of the breakers have "handle ties".

[Bill Kibbel]

It looks like it first appeared in 2008.

[Robert E Lee]

Thanks guys, the home was built in 1999 so wouldn't have been required on the existing panel, but need to do so on the transfer panel.

[Jeff Remas]

Yep, 2008 was the change with the NFPA 70