Split circuit yoke vs. AFCI

[[email protected]]

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?

 

[[email protected]]

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.

 

[[email protected]]

49:58 GMT, [email protected] 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.

 

[bud--]

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.

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

 

[[email protected]]

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

Good point. They will be Beta tested in the customer's home.

 

[Matthew Beasley]

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?

 

[[email protected]]

| |
|> 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?

 

[Paul Hovnanian P.E.]

| |
|> 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.
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.

 

[[email protected]]

| [email protected] 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.

 

[Bud--]

| |
|> 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.

 

[[email protected]]

| [email protected] wrote:
|>
|> | [email protected] 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.

 

[[email protected]]

| [email protected] 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)?

 

[Paul Hovnanian P.E.]

| [email protected] 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.

| 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.

| 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.

 

[Paul Hovnanian P.E.]

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.

 

[Paul Hovnanian P.E.]

| [email protected] wrote:
|>
|> | [email protected] 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.

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

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?

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.

 

[Bud--]

| [email protected] 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)?

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

 

[[email protected]]

| 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).

 

[[email protected]]

| Bud-- wrote:
|>
|> [email protected] 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).

 

[[email protected]]

| 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).

 

[Paul Hovnanian P.E.]

| 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.

'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.

|> |> 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).

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.