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cowboyro
Premium
join:2000-10-11
Shelton, CT

1 edit

Smaller size wire on 20A circuit for dedicated purpose?

I am remodeling a bathroom, also bringing in a dedicated 20A circuit (bathroom used to be on the same circuit as a bedroom).
I am having a major issue running a new wire for the lights above the sink, there is a big AC duct above which blocks access.
Is it allowed to leave the existing 14ga wire considering that the load would be a lousy 2A even if using incandescent lights or there is no way around the 12ga wire? The light fixtures have 18ga wires inside....
If I have to run 12ga it will be a major PITA...
Edit: just to make clear, the wire to the bathroom is 12ga, the only issue is the wire from the switch to the lights.


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
Until the pros come here...

From the NEC rule 240.5(B)(2) : 20A circuits can supply: 18AWG, up to 50 ft of run length; 16AWG, up to 100 ft; 14AWG and larger for any length.

This is not a quote of the actual rule, but it came from a very reliable website
»ecmweb.com/code-basics/flexible- ··· ure-wire


ropeguru
Premium
join:2001-01-25
Mechanicsville, VA
reply to cowboyro
Simple and direct answer, NO...

Stop and think about it. The light fixture wires will never be carrying a load other than the light fixture. The wire from the breaker to the bathroom will be carrying multiple loads that will add up.


cowboyro
Premium
join:2000-10-11
Shelton, CT
said by ropeguru:

Stop and think about it. The light fixture wires will never be carrying a load other than the light fixture. The wire from the breaker to the bathroom will be carrying multiple loads that will add up.

The only issue is running a new wire from the light switch to the fixture. Wire feeding the bathroom is 12ga. I have already ran all others (fan, main light) with 12ga.

robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1
reply to cowboyro
Back in the 50's I believe that it was code to install a lighting circuit using 14 ga on a general purpose 20 amp circuit using 12 ga. I know I've seen it done that way in many houses of that era. My understanding is that changed at some point and all wiring on a 20 amp circuit has to be 12 ga minimum under current code.


dosdoxies
Premium
join:2004-12-15
Wallingford, PA
reply to cowboyro
Why can't you just put the bathroom on a 15 amp breaker? What kind of loads are you expecting to use on this circuit?
--
The more people I meet, the better I like my dogs.


cowboyro
Premium
join:2000-10-11
Shelton, CT
said by dosdoxies:

Why can't you just put the bathroom on a 15 amp breaker? What kind of loads are you expecting to use on this circuit?

Code requires 20A. Worst case I could use existing 15A circuit just for those lights, but I'd rather clean up the mess.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8

1 edit

1 recommendation

reply to alkizmo
said by alkizmo:

Until the pros come here...

From the NEC rule 240.5(B)(2) : 20A circuits can supply: 18AWG, up to 50 ft of run length; 16AWG, up to 100 ft; 14AWG and larger for any length.

This is not a quote of the actual rule, but it came from a very reliable website
»ecmweb.com/code-basics/flexible- ··· ure-wire

Citing this section of the Code is completely wrong. It is specifically for flexible cords and fixture wires, something completely different than what the OP is trying to deal with.
--
The most powerful weapon in the world is ignorance. Politicians exploit it to achieve almost anything they want.



cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
reply to alkizmo
said by alkizmo:

Until the pros come here...

From the NEC rule 240.5(B)(2) : 20A circuits can supply: 18AWG, up to 50 ft of run length; 16AWG, up to 100 ft; 14AWG and larger for any length.

240.5 applies to "Protection of Flexible Cords, Flexible Cables, and Fixture Wires." While all the details of the installation are mentioned, I have a feeling your code doesn't apply here as cowboyro is likely talking about NM cabling. Fixture wiring is more like lamp cords.

240.4(D)(3) does however apply saying that 14ga copper has a max current of 15 amps after any correction factors apply. The whole circuit must be protected by a 15 amp breaker if the 14ga wire is used. This however is against NEC at least back to 2008 which requires at least 1 20amp circuit to a bathroom. It sounds like the only solutions are to run a 15 amp circuit along with the 20 amp one, or to use a different existing 15-amp circuit for the lighting.


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to cowboyro
I thought he was trying to junction to his fixture's wiring (lights above sink).


PSWired

join:2006-03-26
Annapolis, MD
reply to cowboyro
Convert lighting to low voltage and put the power supply near the 12/14 AWG junction?


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
reply to cowboyro
Post a pic of what you're fighting and maybe we can offer some alternative solutions...

guppy_fish
Premium
join:2003-12-09
Lakeland, FL
kudos:4
Reviews:
·Verizon FiOS
reply to cowboyro
It is perfectly acceptable to have a branch segment to the light above the junction box/point 14 awg. For the length that wire is, say 6-8 feet you could run 40 amps on it and still be within the 3% voltage drop rule. Perfectly safe and code complaint to my NEC knowledge.

I'm sure Nunya will set us all right in short order


tp0d
yabbazooie
Premium
join:2001-02-13
Carnegie, PA
kudos:6
Duno if its compliant, but if the junction box is fully accessible, you could fuse the 14ga chunk of wire with a 10-15a fuse contained within the junction box. Would prob have to be a 4x4 box tho..

thats the plumbers point of view.. hehh

-j
--
if it aint broke, tweak it!!
currently on FiOS (kick aZZ!)


nunya
LXI 483
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:13
reply to cowboyro
Nope. 20A circuit must be 12 Ga. wire. There is no justification for doing otherwise in this case.
--
If someone refers to herself / himself as a "guru", they probably aren't.

TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel
reply to robbin
said by robbin:

Back in the 50's I believe that it was code to install a lighting circuit using 14 ga on a general purpose 20 amp circuit using 12 ga. I know I've seen it done that way in many houses of that era. My understanding is that changed at some point and all wiring on a 20 amp circuit has to be 12 ga minimum under current code.

Makes perfect sense why it isn't allowed.

Scenario:

Bob homeowner wants to add something to existing circuit. Decides the lighting circuit would be a convenient place to tap off of, not realizing that portion of the circuit is only 14awg. Potential disaster waiting to happen.


cowboyro
Premium
join:2000-10-11
Shelton, CT
said by TheMG:

Makes perfect sense why it isn't allowed.

Scenario:

Bob homeowner wants to add something to existing circuit. Decides the lighting circuit would be a convenient place to tap off of, not realizing that portion of the circuit is only 14awg. Potential disaster waiting to happen.

Actually it makes no sense in this particular instance as the wire is after the switch but I see the general intent... I'll just hook that light in the old 15A circuit and be done. In a way maybe it's even better to have lights that can be used if the bathroom breaker decides to trip.
Speaking of which... I really hope there is no requirement to have a GFCI breaker on the bathroom circuit... the outlet will be GFCI but I don't want any nuisance trips to require going to the basement at 1AM...

TheMG
Premium
join:2007-09-04
Canada
kudos:3
Reviews:
·NorthWest Tel
said by cowboyro:

said by TheMG:

Makes perfect sense why it isn't allowed.

Scenario:

Bob homeowner wants to add something to existing circuit. Decides the lighting circuit would be a convenient place to tap off of, not realizing that portion of the circuit is only 14awg. Potential disaster waiting to happen.

Actually it makes no sense in this particular instance as the wire is after the switch but I see the general intent...

Believe it or not, I've seen instances where people have tapped into the switched light circuit to add an additional receptacle in a bathroom.

It's dumb because things like battery powered toothbrushes and electric shavers won't charge with the lights off.

However, people are lazy, and will tap into the closest power source, even if it is switched.


pende_tim
Premium
join:2004-01-04
Andover, NJ
kudos:1
Reviews:
·Comcast
reply to guppy_fish
It you go the 4" box route, simply install 2 GFI outlet breakers. One would be a 20A that would be feed from the 12AWG wire and then feed any other bathroom 20A outlets ; and then a second 15A that would be fed from the 20AWG wire that would feed the 14AWG for the light.
--
The difference between genius and stupidity is that genius has its limits.


AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1
said by pende_tim:

It you go the 4" box route, simply install 2 GFI outlet breakers. One would be a 20A that would be feed from the 12AWG wire and then feed any other bathroom 20A outlets ; and then a second 15A that would be fed from the 20AWG wire that would feed the 14AWG for the light.

wouldn't it be easier to fish in new wire?
--
* seek help if having trouble coping
--Standard disclaimers apply.--


pende_tim
Premium
join:2004-01-04
Andover, NJ
kudos:1
Reviews:
·Comcast
said by AVD:

said by pende_tim:

It you go the 4" box route, simply install 2 GFI outlet breakers. One would be a 20A that would be feed from the 12AWG wire and then feed any other bathroom 20A outlets ; and then a second 15A that would be fed from the 20AWG wire that would feed the 14AWG for the light.

wouldn't it be easier to fish in new wire?

From the OP's initial problem statement: "I am having a major issue running a new wire for the lights above the sink, there is a big AC duct above which blocks access."
--
The difference between genius and stupidity is that genius has its limits.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
He could go sideways, or go low.


cowboyro
Premium
join:2000-10-11
Shelton, CT
said by John Galt:

He could go sideways, or go low.

Can't, there are studs and joists blocking, only way is to come from above but that is blocked.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
That's no excuse...!

Post a pic.


cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
reply to pende_tim
said by pende_tim:

It you go the 4" box route, simply install 2 GFI outlet breakers.

Can you please point to one of these GFI outlet breakers. I'd like to know more about them.

One would be a 20A that would be feed from the 12AWG wire and then feed any other bathroom 20A outlets ; and then a second 15A that would be fed from the 20AWG wire that would feed the 14AWG for the light.

Presuming you meant that the second 15A that would be fed from the 12AWG wire, that would be against code. GFI outlets are not overcurrent breakers and can't be used as such. They do make GFI breakers which serve as both a GFI and overcurrent protector, but that wouldn't work for what you are suggesting.


cowboyro
Premium
join:2000-10-11
Shelton, CT

1 recommendation

reply to John Galt
said by John Galt:

That's no excuse...!
Post a pic.

I already closed the ceiling and floor. Side would involve a 90 degree turn behind studs.
I'll just use the 15A circuit for those lights.

nonymous
Premium
join:2003-09-08
Glendale, AZ
reply to cowboyro
A real electrician would do it to code and just knock out ceiling and or floor and tell you to redo it. Then if you could not do it yourself they would have a relative or friend that could do it at a special cost for you.

mrg123

join:2004-02-05
Berthoud, CO
So long as the OP keeps the bathroom light on the original 14-gauge circuit (with a 15-amp breaker) while installing a new 12-gauge 20-amp circuit for the outlet, then he is code compliant (assuming he does everything else correctly).

The outlet needs to be a GFCI receptacle outlet, or on a GFCI breaker. His choice. The 20-amp circuit is not allowed to supply any other loads besides receptacle outlets in this bathroom, UNLESS any such other loads are receptacle outlets in a different bathroom which also has a separate circuit for lighting/fans. (The NEC lets you either use a 20-amp circuit for all loads, including lights, in a single bathroom OR it allows a 20-amp circuit to be shared amongst multiple bathrooms if all such bathrooms utilize a different circuit for lighting/fans.)

The 15-amp lighting circuit does not need GFCI protection. It might need AFCI protection though, depending on whether it supplies loads in other locations which require AFCI protection (I think, but am not sure, that bathroom lighting loads do not require AFCI.)

Jeff