Split circuit yoke vs. AFCI

There are some uses for having 2 separate circuits on a single receptacle yoke. This is often done in kitchens to safely provide sufficient power
at one point when two appliances together would otherwise overload one circuit. Many kitchen appliances can easily do that. Sometimes these are wired as a shared neutral, either daisy-chained with other receptacles or wired dedicated for maximum power availability. Or they can be wired with separate neutrals. But in either case they must be switched off in common at the breaker [210.7(B)]. With NEC 2008 now moving to near full AFCI protection for dwellings [210.12(B)] there is a conflict. How do you provide the required AFCI protection on a 2-pole (whether neutral is or is not shared) 120 volt circuit? A 2-pole AFCI breaker would be required. To date, only Cutler-Hammer makes these. Square-D does not, and in one document, indicated they did not want to because that would encourage shared neutral circuits (which are considered less safe). However, this is still an impact even for circuits that don't involve a shared neutral. How would _you_ wire a split-yoke dual-circuit 120 volt duplex receptacle fed with dual-neutral wiring to the breaker originating the circuit under NEC 2008 rules when the panel is a Square-D QO type?
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On 25 Dec 2006 14:49:58 GMT, snipped-for-privacy@ipal.net wrote:

It does not apply to kitchens, garages or outside outlets.
This is the current language after the comment phase.
Comment 2-119 210.12(B) Panel Action: Accept in Principle in Part Vote: Vote was unanimous because this was referred to the action on Comment 2-95 The panel took a more measured approach to the AFCI expansion through the action on Comment 2-95. See the commentary on Comment 2-95 (below) for more information. The NEMA reps recommend voting in favor of the panel action with an affirmative comment on vote (only to note that the panel statement should reference 2-95 instead of 2-85). Comment 2-95 revised the text of 210.12(B) to read as follows: (B) Dwelling Units. All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sun rooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter, combination type installed to provide protection of the branch circuit. The vote on this comment was 7-3-1. IBEW, IAEI and IEC voted negative because they believe the expansion should have been to all circuits.
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On Mon, 25 Dec 2006 10:33:32 -0500 snipped-for-privacy@aol.com wrote: | On 25 Dec 2006 14:49:58 GMT, snipped-for-privacy@ipal.net wrote: | |>With NEC 2008 now moving to near full |>AFCI protection for dwellings [210.12(B)] there is a conflict. How do you |>provide the required AFCI protection on a 2-pole (whether neutral is or is |>not shared) 120 volt circuit? | It does not apply to kitchens, garages or outside outlets. | | This is the current language after the comment phase. | | Comment 2-119 210.12(B) | Panel Action: Accept in Principle in Part Vote: Vote was unanimous | because this was referred to the action on Comment 2-95 | The panel took a more measured approach to the AFCI expansion through | the action on Comment 2-95. See the commentary on Comment 2-95 (below) | for more information. | The NEMA reps recommend voting in favor of the panel action with an | affirmative comment on vote (only to note that the panel statement | should reference 2-95 instead of 2-85). | Comment 2-95 revised the text of 210.12(B) to read as follows: | (B) Dwelling Units. All 120-volt, single phase, 15- and 20-ampere | branch circuits supplying outlets installed in dwelling unit family | rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, | sun rooms, recreation rooms, closets, hallways, or similar rooms or | areas shall be protected by a listed arc-fault circuit interrupter, | combination type installed to provide protection of the branch | circuit. | The vote on this comment was 7-3-1. IBEW, IAEI and IEC voted negative | because they believe the expansion should have been to all circuits.
As in other amperage and other voltage? What does one do if the breakers are not available in the voltage/amperage needed? That's a realistic issue, currently, given the lack of available variety. Maybe the 2008 code will help expand that by showing to the manufacturers that things are moving in that direction. I'm sure they'd like to sell more AFCI. But I also think they need to be making the models before the code says it is required. That, or make the code say that breakers of a given manufacturer may not be used for anything unless they make the full variety in AFCI versions.
Another area of expansion in the future is non-dwelling units. That will be harder to accomplish because of many industrial exceptions that will have to be made.
Apparently some issues have been found with AFCI in just bedrooms, e.g. some appliances that false trip them. As this expansion takes place, there could be more.
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snipped-for-privacy@aol.com wrote:

Do combination type AFCIs, required in about a year, exist on the market yet? Track record?
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wrote:

Good point. They will be Beta tested in the customer's home.
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Break both the neutral and hot tabs off and run separate neutrals back to the panel?
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| | |> How would _you_ wire a split-yoke dual-circuit 120 volt duplex receptacle |> fed with dual-neutral wiring to the breaker originating the circuit under |> NEC 2008 rules when the panel is a Square-D QO type? |> | | Break both the neutral and hot tabs off and run separate neutrals back to | the panel?
But how to you comply with 210.7(B) -and- 210.12(B) in the 2008 code?
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snipped-for-privacy@ipal.net wrote:

You don't power devices on one yoke from more than one branch circuit. If the potential load per receptacle is so high that any additional load can't be tolerated, then run a dedicated branch circuit to a single receptacle.
Kitchen circuits typically split a number of duplex receptacles between two 20A branch circuits (not counting dedicated load circuits). So the possibility of multiple loads per branch circuit still exists. It is probably best to split a duplex receptacle as a last resort, since most people will assume that duplex receptacles' loads will be applied to the same branch circuit and to avoid using both halves of a duplex in the event of large appliances.
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wrote: | snipped-for-privacy@ipal.net wrote: |>
|>
|> | |> | |> |> How would _you_ wire a split-yoke dual-circuit 120 volt duplex receptacle |> |> fed with dual-neutral wiring to the breaker originating the circuit under |> |> NEC 2008 rules when the panel is a Square-D QO type? |> |> |> | |> | Break both the neutral and hot tabs off and run separate neutrals back to |> | the panel? |> |> But how to you comply with 210.7(B) -and- 210.12(B) in the 2008 code? | | You don't power devices on one yoke from more than one branch circuit.
Then what is the existance of 210.7(B) for?
What are those break-off tabs for?
| If the potential load per receptacle is so high that any additional load | can't be tolerated, then run a dedicated branch circuit to a single | receptacle.
What if there is only once space, can't be expanded, and you now need more capacity?
| Kitchen circuits typically split a number of duplex receptacles between | two 20A branch circuits (not counting dedicated load circuits). So the | possibility of multiple loads per branch circuit still exists. It is | probably best to split a duplex receptacle as a last resort, since most | people will assume that duplex receptacles' loads will be applied to the | same branch circuit and to avoid using both halves of a duplex in the | event of large appliances.
I've seen such splits in more places than kitchens. Like in every room of a house, though the same two circuits covered a lot of rooms. It was probably a shared neutral. But at least there was plenty of capacity at each place.
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snipped-for-privacy@ipal.net wrote:

For switched outlets. And for feeding each half of the duplex receptacle from either side of a multiwire circuit, provided it is fed from a 2-pole breaker (or other means that satisfy 210.7(B)). If the 2008 code will require 2 pole breakers for all multiwire circuits (split receptacles or not) and manufacturers will not provide these that also meet the AFCI requirements, then I guess we won't be putting in any more multiwire branch circuits.

Time for a new panel or a sub-panel.

Gaze fondly upon such installations, for they will become extremely rare (if not nonexistent) after 2008.
Those designers and electricians that can't solve capacity problems by other means will become scarce as well.
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wrote: | snipped-for-privacy@ipal.net wrote: |>
wrote:
|> |>
|> |>
|> |> | |> |> | |> |> |> How would _you_ wire a split-yoke dual-circuit 120 volt duplex receptacle |> |> |> fed with dual-neutral wiring to the breaker originating the circuit under |> |> |> NEC 2008 rules when the panel is a Square-D QO type? |> |> |> |> |> | |> |> | Break both the neutral and hot tabs off and run separate neutrals back to |> |> | the panel? |> |> |> |> But how to you comply with 210.7(B) -and- 210.12(B) in the 2008 code? |> | |> | You don't power devices on one yoke from more than one branch circuit. |> |> Then what is the existance of 210.7(B) for? |> |> What are those break-off tabs for? | | For switched outlets. And for feeding each half of the duplex receptacle | from either side of a multiwire circuit, provided it is fed from a | 2-pole breaker (or other means that satisfy 210.7(B)). If the 2008 code | will require 2 pole breakers for all multiwire circuits (split | receptacles or not) and manufacturers will not provide these that also | meet the AFCI requirements, then I guess we won't be putting in any more | multiwire branch circuits.
I will suggest that AHJ not adopt NEC 2008 w/o adding some provision that provides for some way around it, or to force the manufacturers to make the required equipment.
Of course there are some options already. Cutler-Hammer does make 2-pole AFCI breakers. Also, there are such things as handle ties.
I'm also fully in favor of disqualifying Square-D and any other manufacturer that refuses to make AFCI in 2-pole.
|> | If the potential load per receptacle is so high that any additional load |> | can't be tolerated, then run a dedicated branch circuit to a single |> | receptacle. |> |> What if there is only once space, can't be expanded, and you now need |> more capacity? | | Time for a new panel or a sub-panel.
Or in my case, tell Square-D to stuff it.
|> | Kitchen circuits typically split a number of duplex receptacles between |> | two 20A branch circuits (not counting dedicated load circuits). So the |> | possibility of multiple loads per branch circuit still exists. It is |> | probably best to split a duplex receptacle as a last resort, since most |> | people will assume that duplex receptacles' loads will be applied to the |> | same branch circuit and to avoid using both halves of a duplex in the |> | event of large appliances. |> |> I've seen such splits in more places than kitchens. Like in every room |> of a house, though the same two circuits covered a lot of rooms. It was |> probably a shared neutral. But at least there was plenty of capacity at |> each place. | | Gaze fondly upon such installations, for they will become extremely rare | (if not nonexistent) after 2008. | | Those designers and electricians that can't solve capacity problems by | other means will become scarce as well.
How would you do it without enlarging the box?
At least the French did this right with a modular system that has small single outlets instead of the oversized ones we have. Then the box can be just the right size for what is needed.
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snipped-for-privacy@ipal.net wrote:

If you bring up the discrepancy between the code and the availability of suitable equipment, they might just disallow multiwire circuits in residences.

What do you mean by 'enlarging the box'? It sounds like you are modifying an existing branch circuit. In that case, upgrading to a AFCI may not be required.
If you are adding a new branch circuit, you put in whatever size box the receptacle configuration requires when you are roughing in the new wiring.
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wrote:
| If you bring up the discrepancy between the code and the availability of | suitable equipment, they might just disallow multiwire circuits in | residences.
The availability is specific to manufacturers. For most things Square-D and Cutler-Hammer provide a good selection and others less so. For this (multiwire single circuit, or multicircuit on one yoke) Square-D is now one of the lesser manufacturers. The question is, will Square-D be up to the task of making multicircuit on one yoke work (I don't care about the multiwire single circuit ... e.g. shared neutral ... I won't oppose those being prohibited).
If one runs a non-AFCI 20 amp 3-wire circuit from a Square-D main panel to a small 2-space Cutler-Hammer subpanel, where a 2-pole AFCI breaker is installed, would it be considered that the circuit originates there for the purposes of the code? Or what about a larger subpanel. If one has Square-D already, this could be a start in the process of migrating to Cutler-Hammer.
|> |> I've seen such splits in more places than kitchens. Like in every room |> |> of a house, though the same two circuits covered a lot of rooms. It was |> |> probably a shared neutral. But at least there was plenty of capacity at |> |> each place. |> | |> | Gaze fondly upon such installations, for they will become extremely rare |> | (if not nonexistent) after 2008. |> | |> | Those designers and electricians that can't solve capacity problems by |> | other means will become scarce as well. |> |> How would you do it without enlarging the box? | | What do you mean by 'enlarging the box'? It sounds like you are | modifying an existing branch circuit. In that case, upgrading to a AFCI | may not be required.
It would be adding a 2nd circuit but it needs to fit in the existing one-gang space.
| If you are adding a new branch circuit, you put in whatever size box the | receptacle configuration requires when you are roughing in the new | wiring.
The option to put in a two-gang box does not exist for complicated reasons.
Note, this is going to be done before 2008 if it's going to be done at all so really the 2008 code won't be an issue. But I want to understand all the option as if it were, to really understand if there are burdens being added to the code (considering AFCI itself isn't one).
I just think that if appropriate pressure were put on manufactures to make all the various components (Square-D, for example, does make a reasonable range of GFCI breakers in 1-pole and 2-pole), then it would be fine to go with the new code. Otherwise I think the code should have had an exception that applied in the narrow cases where a 2-pole AFCI breaker is required but isn't available (210.7(B) has the effect of imposing such a requirement in rare cases).
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snipped-for-privacy@ipal.net wrote:

'There' being where? Branch circuits originate from the last panel/OCPD. So this would be the subpanel. If the AFCI is a separate device from the branch circuit OCPD, there are some additional restrictions in the NEC. But if the functions are combined in one device, I don't think its a problem.

Sounds like a loophole to me. And perhaps it would to the NEC authors as well. AFCI equipment is expensive and if the loophole was created, every cheapskate electrician would claim a need to wire an entire house with multiwire circuits, citing 'special circumstances' that rule out two-wire circuits, require splitting duplex receptacles and the unavailability of suitable equipment.
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wrote:
| Sounds like a loophole to me. And perhaps it would to the NEC authors as | well. AFCI equipment is expensive and if the loophole was created, every | cheapskate electrician would claim a need to wire an entire house with | multiwire circuits, citing 'special circumstances' that rule out | two-wire circuits, require splitting duplex receptacles and the | unavailability of suitable equipment.
OK, I can see that. Maybe they should have told the manufacturers up front that they expect to see a wide range of products available and tested before moving forward on this (manufacturers apparently are part of the push because it's more revenue for them). But now that the deed is done, maybe if people start recommending only C-H for AFCIs, then Square-D might expand the product line (at least in QO).
Maybe a trip to the big box store this weekend and see if they have handle ties and if they fit the AFCIs (which I know they have).
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snipped-for-privacy@ipal.net wrote:

You can probably use a handle tie, like QO1HT.
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Bud-- wrote:

If they work with AFCI breakers, yes. If the breaker manufacturers are adamant about discouraging mutiwire circuits, they may make the handles incompatible.
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wrote: | Bud-- wrote: |>
|> >
|> > | |> > | |> > |> How would _you_ wire a split-yoke dual-circuit 120 volt duplex receptacle |> > |> fed with dual-neutral wiring to the breaker originating the circuit under |> > |> NEC 2008 rules when the panel is a Square-D QO type? |> > |> |> > | |> > | Break both the neutral and hot tabs off and run separate neutrals back to |> > | the panel? |> > |> > But how to you comply with 210.7(B) -and- 210.12(B) in the 2008 code? |> > |> You can probably use a handle tie, like QO1HT. | | If they work with AFCI breakers, yes. If the breaker manufacturers are | adamant about discouraging mutiwire circuits, they may make the handles | incompatible.
I think it would be inappropriate for the manufacturers to decide on product line based on such a desired. The NFPA CMP's, OTOH, should be in that role. And I certainly would not be opposed to prohibiting multiwire circuits serving multiple outlets or any L-N-only outlet. But I think a dual-circuit to a duplex device is perfectly acceptable when wired with separate neutrals, whether as a single outlet for each circuit, or as multiple outlets with those 2 circuits staying together to serve other duplex outlets in a like way. Dual-neutral NM cable (with a common EGC) is already made (or we could have used 3-phase cable if the code allowed remarking blue to be the "other white" in the limited case of such cable, which I think is perfectly safe in dwelling units not supplied with three phase power).
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| snipped-for-privacy@ipal.net wrote:
|>
|> | |> | |> |> How would _you_ wire a split-yoke dual-circuit 120 volt duplex receptacle |> |> fed with dual-neutral wiring to the breaker originating the circuit under |> |> NEC 2008 rules when the panel is a Square-D QO type? |> |> |> | |> | Break both the neutral and hot tabs off and run separate neutrals back to |> | the panel? |> |> But how to you comply with 210.7(B) -and- 210.12(B) in the 2008 code? |> | You can probably use a handle tie, like QO1HT.
Are accessory handle ties considered qualifying for 210.7(B)?
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snipped-for-privacy@ipal.net wrote:

Far as I know they are. A common trip is not required. SqD makes the handle tie.
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