Three pole breaker

[dneveaux]

I know a three pole breaker is required in feeding a three phase motor. My question is if I am feeding 3 separate outlets from a twist lock (L 21-30) using a 5 wire so cord (10/5) do I need to put the twist lock on a three pole breaker? I have a box with three RV receptacles and don't want one tripping causing all three to trip. If someone knows this answer can you point me in the right direction of the code to be able to do this or not? Thanks.

Dave

 

[don_resqcapt19]

Under the 2008 code this circuit needs a common disconnect. That would not require the use of a 3 pole breaker. Single pole breakers with a handle tie would serve the purpose. The handle tie may or may not cause the other breakers to open when one breaker trips. 210.4(B)

 

[dneveaux]

Wouldn't the twist lock be considered a means of disconnect?

 

[Dennis Alwon]

Wouldn't the twist lock be considered a means of disconnect?

Here is the 2008 NEC art. 210.4

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 equipment.
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.
(C) 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.

I don't believe anyone makes 3 pole handle ties but I am not certain of that.

 

[LarryFine]

Don't forget that the twistlock receptacle in question is a single device, which requires the common trip all by itself, even without the cord to the splitter box inserted.