Why NOT to use #12 wire for lighting circuits

[alfredeneuman]

His idea was he had done to many service calls were the issue was on the receptacles circuits was somebody had put 14 guage on a 20 amp circuit and was overloading the circuit.

The ampacity of #14 is 15A on general circuits and has nothing to do with the circuit being overloaded.

 

[sberry]

The ampacity of #14 is 15A on general circuits and has nothing to do with the circuit being overloaded.

So true,,, while it is a code violation may not even be unsafe in some circumstances. I have seen guys use 14 for ground pigtails in congested boxes with daisey chains. Not legal but has 15 outlets anyway, 6 inches of smaller wire doesn't mean squat in the grand scheme in that app.

 

[Brandon_oma#692]

Thanks for this discussion. I am getting material for my garage. Plan was to use all 12. I will get 14 for the outlets in the ceiling for lights.

 

[alfredeneuman]

I have seen guys use 14 for ground pigtails in congested boxes with daisey chains.

One guy I worked with/against would pull a #14 ground wire in every inch of flex conduit for 20A circuits, and argued it always passed inspections..... until 1 time it didn't He was red tagged, and had to repull all the wire on a particularly big project. The owner of the company sure was pissed

 

[engineer2]

In Illinois you aren't allowed to use 14.

Never heard of that. AFAIK, the state does not dictate electrical code and leaves it up to local government. Could be local code. Code varies widely by location.

 

[alfredeneuman]

AFAIK, the state does not dictate electrical code and leaves it up to local government.

NEC Adoption in State Codes of Regulations

As of this writing, in April 2019, the following states have adopted the 2008 edition of the NEC into their state Codes of Regulations:

Illinois, Indiana, and Kansas.

....and the NEC doesn't have any restriction against #14

 

[engineer2]

I assume they require NEC, but I'm not aware of any code enforcement department for our state other than as an "informational resource", but you never know. Localities can dictate things like EMT vs Romex, etc.

 

[2level]

I've never seen a light fixture that used a 20A plug.

Neither have I. Some 'lighting circuits' are multipurpose, some are setup for easy 'step up', especially in a garage. I've got one 20A circuit that has overhead lights on it plus 4 wall mounted receptacles. Those receptacles and lights are fed thru a 20A switch, and have wall mounted light fixtures plugged into them when I'm painting, but may have a shop vac, air compressor, welder, etc. plugged in at other times.

Have you ever seen a lighting circuit with a **** ton of holiday lights, both incandescent and LED, plugged in to it?

 

[alfredeneuman]

Have you ever seen a lighting circuit with a **** ton of holiday lights, both incandescent and LED, plugged in to it?

None with 20 amp plugs

 

[exranger06]

I recently installed another light fixture in my garage and I tapped it off an existing 20A receptacle circuit. So I had to run #12 for that one. Wasn't a big deal; I was replacing a plug-in "shop light" with a hardwired fixture, so I already had a receptacle box right above the fixture and most of the wiring was already done. I just had to add a conductor for the switched leg and pulled it through the existing EMT to an existing junction box. Then I just added a small length of EMT from that box down to the new switch box and pulled the conductors through. I ran about a foot of flex conduit from the receptacle box into the fixture and pulled the wires through. I made some connections and I was done.

 

[American Locomotive]

12 gauge is just completely unnecessary these days with modern LED lighting. You could light an entire house on a single 15A breaker. Shoot, you could light your house, your neighbors house and maybe their neighbor's house on a single 15A breaker with LEDs.

I hope they introduce 16 gauge wire and 10A breakers for lighting circuits. 12 and 14 gauge is just such a waste of copper with LED lighting.

 

[alfredeneuman]

I hope they introduce 16 gauge wire and 10A breakers for lighting circuits.

Ampacity of #16 TFFN is 8 amps, and they already make 10A breakers.

 

[nsula_country]

2012 we built our house and we used 12ga 100%. Even the dedicated smoke alarm circuit with 6 smoke detectors. Dedicated 20A for security alarm. Dedicated 20A for sewer aerator.

Logic was 1 wire size, 1 breaker size. Any circuit can be MODIFIED in the future without concerns of ampacity.

CT

 

[Falcon67]

I just scarfed 11 2' x 4' ceiling grid type LED light fixtures from some take-out warranty replacements here at work. The fixtures are rated at 40w max each.

58 fixtures in a building, probably running at 277v - so the entire group of grid lights is pulling less than 10a? And yep, there's 12 gauge in every box that I've seen in that construction. It was a bit LOL.

 

[tonyciambrone]

Stranded then has the issues of termination.............

some sparky's call them staycons...but crimp on spade terminals..

I personally like them best out of all receptacle connections, and for me, it is faster than looping solid (maybe because I am not good at it).

I also like to use solid in conduit for short runs when I can just push it, but stranded makes pulling wire so much easier..

 

[alfredeneuman]

some sparky's call them staycons...but crimp on spade terminals..

StaKon is the name that Thomas and Betts trademarked for their crimp connectors.

 

[Bert_]

I run lots of #14 for lighting. Especially in houses these days when people want a bunch of can lights. Much easier and faster than #12.

 

[nsula_country]

StaKon forks are awesome for receptacles and switches. Entire shop is done with them.

CT

 

[Jim greengo]

2012 we built our house and we used 12ga 100%. Even the dedicated smoke alarm circuit with 6 smoke detectors. Dedicated 20A for security alarm. Dedicated 20A for sewer aerator.

Logic was 1 wire size, 1 breaker size. Any circuit can be MODIFIED in the future without concerns of ampacity.

CT

What size breaker did you use for the furnace?

 

[Jim greengo]

I just scarfed 11 2' x 4' ceiling grid type LED light fixtures from some take-out warranty replacements here at work. The fixtures are rated at 40w max each.

58 fixtures in a building, probably running at 277v - so the entire group of grid lights is pulling less than 10a? And yep, there's 12 gauge in every box that I've seen in that construction. It was a bit LOL.

That's common for commercial work,check the size of the whips feeding the lights though.

 

[nsula_country]

What size breaker did you use for the furnace?

1st floor CH260, CH230. 2nd floor CH260.

CT

 

[Jim greengo]

1st floor CH260, CH230. 2nd floor CH260.

CT

And those are what size breakers?

 

[Bert_]

And those are what size breakers?

Cutler Hammer CH 2 pole 60, 2 pole 30, and 2 pole 60

 

[n20junkie]

I just run 12 ga. I’ve never wished for smaller wires, but I sure have wished for bigger wires at times.

 

[PugetDude]

I used all 12 gauge when I did my house. Didn't want to mess with 14 and 12.
I didn't have any issues with all 12 gauge.

Same here. Cost difference was minimal.

 

[Jim greengo]

Cutler Hammer CH 2 pole 60, 2 pole 30, and 2 pole 60

Are we talking furnace,or air handler?<

 

[theoldwizard1]

Last year when I had a friend who owns a commercial electrical construction wire my shop he said that he only uses 12 guage wire for his lighting circuits. He did not have 14 on his trucks or in stock. His idea was he had done to many service calls were the issue was on the receptacles circuits was somebody had put 14 guage on a 20 amp circuit and was overloading the circuit.

That specific example is the fault of the installer. It should have been caught by the inspector !

I do understand sberry's argument (only so much space on your truck), but the point I was making in post #1, is that there are cases where you have a wire chase and the additional bulk of multiple 12/2 NM-B makes it a pain in the **** ! Landing all of the wires for 3 switch circuit in a standard depth double boxes is also going to be a challenge. Even though a "professional" was consulted, I know there is probably a better solution !

Also, this homeowner/DIYer has a ridiculous number of "home runs" for a 4 car garage. I think he has 2 circuits for lights and probably 5 or 6 for receptacles NOT including the basement bathroom. This does not count the 5 or 6 240V circuits for the electric dryer, the electric stove and the electric "on demand" water heater.

 

[NUTTSGT]

I hope they introduce 16 gauge wire and 10A breakers for lighting circuits. 12 and 14 gauge is just such a waste of copper with LED lighting.

OH Boy, that sounds like job security for me.

I can see the slumlords having their "electricians" replacing 10A breakers with 15s or 20s because the tenants are complaining about tripping breakers.


Woo-hoo, we're running 2 1500W electric heaters on the circuit but have no issue until we try to use the microwave.

 

[sberry]

One of the reasons to run smaller, even extra wires is convenience. 3 ways etc as anything that can be hard wired is all the better and more reliable than gadgets. I agree there could be a place for lighter circuits. There is the convenience today of being able to add additional losd, the neutral at boxes helps, I have had occasion to take advantage of that.
Good design has lights and recepts separate, so much so there isn't means in most places to allow the user to add heaters to this type of circuit,,,and it is overcurrent protected.

 

[American Locomotive]

OH Boy, that sounds like job security for me.

I can see the slumlords having their "electricians" replacing 10A breakers with 15s or 20s because the tenants are complaining about tripping breakers.


Woo-hoo, we're running 2 1500W electric heaters on the circuit but have no issue until we try to use the microwave.

Why would 10A dedicated lighting circuits be tripping? Why would a tenant be running a heater off a lighting circuit?

 

[CJ7VFR]

Why would 10A dedicated lighting circuits be tripping? Why would a tenant be running a heater off a lighting circuit?

Because they can!

Tenants in apartments do anything and everything to jack **** up. They don't know enough, don't care enough, and the end result is service calls to the landlord on Christmas Eve, at 11:30pm when they say the heat is off.

Landlord leaves his family, goes over to apartment, and finds that tenant has replaced the light bulb in the bedroom light fixture with one of those screw in receptacle adapters so they can plug in the 1500 watt electric heater near the bed because they are cold. And what happens? blown breakers, or worse, toasted wiring.

Think it does not happen? Then you have never rented a place out to anyone!!

Jim

 

[nsula_country]

Are we talking furnace,or air handler?<

You seem to be an electrical and HVAC veteran. I was hoping you could read between the lines. So I answered with the cat no of the breakers.

You asked what size breaker we used for furnace(s). I answered professionally by using the catalog number for the breakers. CH260 = Cutler-Hammer CH 2 pole 60 amp. CH230 = Cutler-Hammer CH 2 pole 30 amp.

If I need a CH260 and a CH230, I'd assume this is an air handler with about 15kw worth of heat strip. Same for the CH260 in the other, 10kw heat strip.

All electric house. No gas. Heat Pump Air Handler with Heat Strips.

Shop has 2, CH260's... 20kw heat strip.

CT

 

[nsula_country]

Because they can!

Tenants in apartments do anything and everything to jack **** up. They don't know enough, don't care enough, and the end result is service calls to the landlord on Christmas Eve, at 11:30pm when they say the heat is off.

Landlord leaves his family, goes over to apartment, and finds that tenant has replaced the light bulb in the bedroom light fixture with one of those screw in receptacle adapters so they can plug in the 1500 watt electric heater near the bed because they are cold. And what happens? blown breakers, or worse, toasted wiring.

Think it does not happen? Then you have never rented a place out to anyone!!

Jim

Tenants have opened my eyes the past 20 years! Don't assume it CANNOT HAPPEN!

CT

 

[nsula_country]

That specific example is the fault of the installer. It should have been caught by the inspector !

I do understand sberry's argument (only so much space on your truck), but the point I was making in post #1, is that there are cases where you have a wire chase and the additional bulk of multiple 12/2 NM-B makes it a pain in the **** ! Landing all of the wires for 3 switch circuit in a standard depth double boxes is also going to be a challenge. Even though a "professional" was consulted, I know there is probably a better solution !

Also, this homeowner/DIYer has a ridiculous number of "home runs" for a 4 car garage. I think he has 2 circuits for lights and probably 5 or 6 for receptacles NOT including the basement bathroom. This does not count the 5 or 6 240V circuits for the electric dryer, the electric stove and the electric "on demand" water heater.

Interesting you brought this up.

When building out the shop, I WAS going to pull 12 for lights (conduit). 3 bays, 8, 4 lamp T8 fixtures per bay. With other circuits that I had planned to pull in that particular conduit, plus 3 sets of travelers. I chose 4, 15 amp circuits. (CH115). 4th 15a circuit was for ceiling fans, exit signs/lights, outdoor motion lights. It was easier to go to supply house and buy 6 spools of 14 than to re-run with 1" EMT.

These 4 circuits are dedicated and would be difficult to "accidently" add on to... After I'm gone.

CT

 

[u2slow]

Screw #12.... lighting needs to be done with #10!

IMO, there's no point is using larger wire than the connected load demands. Another reason to keep lighting circuits separate.

 

[Brandon_oma#692]

If you have a wall outlet on a switch for a lamp is that part of the lighting circuit normally? or with the other outlets? I could see someone trying to be smart and using that for a space heater so it is turned off when they turn off the light.

At my house the whole main floor is 1 circuit. Kitchen, living room, bedroom, bathroom, and bedroom. I will be splitting it up after I get the sub panel in the garage done.

 

[Jim greengo]

You seem to be an electrical and HVAC veteran. I was hoping you could read between the lines. So I answered with the cat no of the breakers.

You asked what size breaker we used for furnace(s). I answered professionally by using the catalog number for the breakers. CH260 = Cutler-Hammer CH 2 pole 60 amp. CH230 = Cutler-Hammer CH 2 pole 30 amp.

If I need a CH260 and a CH230, I'd assume this is an air handler with about 15kw worth of heat strip. Same for the CH260 in the other, 10kw heat strip.

All electric house. No gas. Heat Pump Air Handler with Heat Strips.

Shop has 2, CH260's... 20kw heat strip.

CT

Sorry,I dont have Cutler hammer model numbers memorized in my head.
Pretty sure most people would reply with breaker size instead of a part number,but what ever makes you happy.

 

[Jim greengo]

Tenants have opened my eyes the past 20 years! Don't assume it CANNOT HAPPEN!

CT

Tenants and home owners with screwdrivers in general have left my head spinning more than once over the years.

 

[Bopbop]

That specific example is the fault of the installer. It should have been caught by the inspector !

I do understand sberry's argument (only so much space on your truck), but the point I was making in post #1, is that there are cases where you have a wire chase and the additional bulk of multiple 12/2 NM-B makes it a pain in the **** ! Landing all of the wires for 3 switch circuit in a standard depth double boxes is also going to be a challenge. Even though a "professional" was consulted, I know there is probably a better solution !

Also, this homeowner/DIYer has a ridiculous number of "home runs" for a 4 car garage. I think he has 2 circuits for lights and probably 5 or 6 for receptacles NOT including the basement bathroom. This does not count the 5 or 6 240V circuits for the electric dryer, the electric stove and the electric "on demand" water heater.

Yes the error in my example is the mistake of the installer. Yes the inspector should have caught it. Today we lack in a lot of skilled craftsmen in the field. I am a design engineer and hear all of the people I deal with complain they cannot find qualified people. Also the inspections departments have trouble finding and keeping qualified people. I see the inspectors being so over booked that they miss stuff.
In my new 30 x 60 shop I have a 200 amp service. I have 1 lighting circuit for 24 LED high bays it is a 20 amp circuit. I have 5 220 circuits for welders and the air compressor, a 220 for the lift and 8 120 circuits for the receptacles, 2 wall receptacles per circuit. I also have about 20 open circuits.
In my last shop I ran out of capacity and it sucked. In this shop I built in a lot of extra capacity. The cost was maybe $1,000 to $1,500 dollars. Not much in the over all cost I spent but in my mind well worth it.

 

[NUTTSGT]

Because they can!

Tenants in apartments do anything and everything to jack **** up. They don't know enough, don't care enough, and the end result is service calls to the landlord on Christmas Eve, at 11:30pm when they say the heat is off.

Landlord leaves his family, goes over to apartment, and finds that tenant has replaced the light bulb in the bedroom light fixture with one of those screw in receptacle adapters so they can plug in the 1500 watt electric heater near the bed because they are cold. And what happens? blown breakers, or worse, toasted wiring.

Think it does not happen? Then you have never rented a place out to anyone!!

Jim

Tenants have opened my eyes the past 20 years! Don't assume it CANNOT HAPPEN!

CT

Tenants and home owners with screwdrivers in general have left my head spinning more than once over the years.

Yes, yes and yes.


I've seen alot and wondered why hasn't this burnt? Extension cord to outlet strip to extension cord to another outlet strip. Every fuse is a 30A screw in fuses on older 14 gauge wire or knob/tube.