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#180848 - 09/13/08 12:42 AM 210.7(B) vs. 408.36(C)
pdh Offline
Member

Registered: 01/20/05
Posts: 354
NEC 2008 210.7(B):
 Quote:
Multiple Branch Circuits. Where two or more branch circuits supply devices or equipment on the same yoke, a means to simultaneously disconnect the ungrounded conductors supplying those devices shall be provided at the point at which the branch circuits originate.

NEC 2008 408.36(C) [2005 408.36(E)]:
 Quote:
Delta Breakers. A 3-phase disconnect or overcurrent device shall not be connected to the bus of any panelboard that has less than 3-phase buses. Delta breakers shall not be installed in panelboards.

How can two separate circuits in a 120/240 volt single phase system be attached to a combination duplex receptacle with NEMA 5-XXR and NEMA 6-XXR, with a common handle to meet the simultaneous disconnect rule in 210.7(B) and not violate what appears to be a prohibition in 408.36(C)? Does a 3-pole breaker mean it is a 3-phase disconnect/OCPD? What if 3 separate single pole breakers are tied together with listed handle ties for breakers designed for that, would that make them be a 3-phase disconnect?

Or can this type of receptacle only be connected where the ungrounded conductor of the 120V half is in common with an ungrounded conductor of the 240V half? \:\(

And what is a "Delta Breaker"? A 3-phase breaker for delta systems? Or does 408.36(C) only apply to delta systems (maybe where the midpoint of one winding is grounded)?


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#180851 - 09/13/08 05:38 AM Re: 210.7(B) vs. 408.36(C) [Re: pdh]
KJay Offline
Member

Registered: 11/27/07
Posts: 763
Loc: MA, USA
If I understand correctly, I believe what your referring to is allowed by 210.4[B] and 210.4[C], exception No. 2.
The disconnecting means in this instance doesn’t necessarily have to be a common trip. The 2008 Handbook exhibits 210.1 and 210.2 on page 76 and 77 gives an excellent depiction of this.
Hopefully this is on target with what you were asking.

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#180854 - 09/13/08 07:24 AM Re: 210.7(B) vs. 408.36(C) [Re: KJay]
Ralpha494 Offline
Member

Registered: 05/19/04
Posts: 71
Loc: Pewaukee,WI,USA
Here in WI we have a 240v grounded B phase. (The power co. is phasing them out, so you can't get a new 240 grounded B service but they will maintain an existing one.) These panels look just like single phase panels, but need 2-pole breakers rated for 240v to ground. The grounded conductor goes to the neutral bar, and the two other phase conductors go to the 2-pole breaker. I think this is what they are addressing in 408.36(C). I also heard this past week that there is no such thing as a listed three pole handle tie, but can't verify it.

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#180855 - 09/13/08 07:24 AM Re: 210.7(B) vs. 408.36(C) [Re: KJay]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
The "delta breaker" is a strange beast, no longer made, and not relevant here. It's best to dodge that part of the your question entirely. (If you're really curious, stop by the chat room tonight; some of the regular participants actually have them, and can better explain them to us).

Your point is a good one, though. The illustration in the handbook (210.2) presumes that one 'hot' leg will be serving both halves of the receptacle, so they will both be shut off by the same two-pole breaker.

What if you want the two halves to be on completely different circuits?
The ban you mention (found at 384 in pre-2002 editions) appears in a paragraph devoted specifically to the delta breaker. Oddly enough, it appears that the delta breaker was intended for this exact situation - and it's no longer allowed.

Now ... if I may go off on a slight tangent for a moment ...
I've tried to find replacement receptacles like the ones you pictured, and have had some difficulty. I suspect that, like two-prong receptacles, that this arrangement is no longer allowed - except for replacement / maintenance purposes. For all I know, they might not be UL listed any more (won't be the first such situation).

Returning to your question ... I think you are limited by the code to two solutions:
1) Tying a single pole and a two pole breaker together with a handle tie (if you can!); and,
2) Having a separate three pole disconnect switch.

Off the cuff, this looks like a very good issue to address with a proposal to the NEC committee, for the next edition!

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#180856 - 09/13/08 07:33 AM Re: 210.7(B) vs. 408.36(C) [Re: renosteinke]
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
The delta circuit breaker:



As Reno has stated you don't have one of these.

(photo courtesy of NORCAL)

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#180861 - 09/13/08 08:04 AM Re: 210.7(B) vs. 408.36(C) [Re: pdh]
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1296
Loc: Alaska
Being that the OP metioned that the panel is a single phase system, I doubt but not impossible I guess a delta breaker would even fit in the panel (different Breaker frames).

It would be a AHJ question by allowing a 3 pole breaker in the single phase panel. It would be a case by case basis. Personally I do not see why it would be an issue using a 3 pole breaker.

It is as safe or safer then a disconnect since it would be two power sources in the same diconnect which is not typical and with the added cost, you do not achieve anything. I would go as far labling the panel as 120/240 1 phase panel.

If a 3 pole breaker in a single phase panel throws the next guy/gal that goes in the panel, that is an indicator he/she is over their head and need to call someone who knows what they are doing.


Edited by sparkyinak (09/13/08 08:04 AM)
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#180862 - 09/13/08 09:47 AM Re: 210.7(B) vs. 408.36(C) [Re: sparkyinak]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
A SqD 3 phase breaker will fit in a single phase panel.
(at least the old ones, there may be some kind of rejection device now)
I suppose it would allow your 5-15/6-15 device to be on separate circuits and still be compliant but I bet it is a 110.3(B) violation.
Usually this arrangement is when you have a 120v outlet on a 240v single phase circuit where a neutral is provided.
This is a multiwire circuit with a 240v load if you want to look at it the other way.
It is not really unusual at all. Think about the light in your oven.
_________________________
Greg Fretwell

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#180866 - 09/13/08 12:48 PM Re: 210.7(B) vs. 408.36(C) [Re: gfretwell]
KJay Offline
Member

Registered: 11/27/07
Posts: 763
Loc: MA, USA
This is interesting.
I still have some T&B 20A 3-pole plug-in CB’s in stock somewhere. I think maybe some Siemans QP too.
Are manufactures not making 3-pole plug-in breakers anymore?

This excerpt from the 2007 UL white Book (DIVQ) doesn’t seem to limit the number of poles or mention receptacles by name, but it also doesn’t appear to exclude them.

“Multi-pole common trip circuit breakers rated 120/240 V ac are suitable for use in a single-phase multi-wire circuit, with or without the neutral connected to the load, where the voltage to ground does not exceed 120 V.”

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#180867 - 09/13/08 03:01 PM Re: 210.7(B) vs. 408.36(C) [Re: KJay]
pdh Offline
Member

Registered: 01/20/05
Posts: 354
A duplex 5-20R would be easy to split into 2 separate circuits. A 2-pole breaker would easily do the job with 3-wire cable for shared neutral, or 4-wire cable for split neutral. For the latter, you'll need to find dual circuit cable since you can't remark the blue wire of three phase cable as an extra neutral per 200.6(A). I suppose you could also do it with one of those duplex breakers (no shared neutral, must be split neutral only) if the panel accepts them and you can find a way to tie the handles together (I haven't seen that).

A duplex 6-20R would be a lot harder to split into 2 separate circuits, since you'll need to find a 4-pole breaker. Maybe one of those 2-pole duplex breakers (Cutler-Hammer has them in the BR series) with some kind of handle tie over all 4 handles (I haven't seen that).

What does "at the point where the branch circuits originate" in 210.7(B)? There is similar wording in 210.4(B). Does that mean the actual breakers in the panel? What if I put a 40A 2-pole breaker in the panel and feed that to a small subpanel immediately adjacent to the main panel with a pair of 20A 2-pole breakers. Would the one 40A 2-pole breaker meet the requirement of 210.7(B), or does it have to be the last point where circuits branch out at breakers?

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#180875 - 09/14/08 10:23 AM Re: 210.7(B) vs. 408.36(C) [Re: pdh]
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
A delta breaker was designed to allow a three phase circuit to be fed from a single phase panel. These breakers are no longer manufactured (I believe Square D stopped making them 30 years ago). They were used where the service was a 240/120 3Phase 4Wire and only one three phase load was being served.

408.36(C)has nothing to do currently built equipment, it should probably be retired just like rosettas were a few cycles back.

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