20 Amp Circuit with 15 Amp Light Switches

lakeroadster · Oct 30, 2016

So I'm out in the barn yesterday and noticed the light switches that the Sparky's installed are 15 amp..... Opened the electric panel and the circuit has a 20 amp breaker :headscrat

Checked and all romex is 12 gauge on the circuit.

Either the switches should be changed to 20 amp

or

The breaker should be changed to 15 amp

Am I right or is there some NEC rule that I am not aware of?

Thanks,

John

Speedy Petey · Oct 30, 2016

A wall switch need to be rated for the load it is controlling, NOT the size of the circuit it is on.

A 15A switch on a 20A circuit is perfectly normal.

klassenl · Oct 30, 2016

Speedy Petey said:
A wall switch need to be rated for the load it is controlling, NOT the size of the circuit it is on.

A 15A switch on a 20A circuit is perfectly normal.

I personally wouldn't be willing to make this statement

wyliesdiesels · Oct 30, 2016

klassenl said:
I personally wouldn't be willing to make this statement

Really? Why is that? U have a code reference that says otherwise?

BTW arguing with a licensed contractor that knows his stuff wont end well for u.

pattenp · Oct 30, 2016

It's ok by NEC 404.14. Sized for load being switched.

wyliesdiesels · Oct 30, 2016

pattenp said:
It's ok by NEC 404.14. Sized for load being switched.

shhhh

I was really wanting his code reference that disallows 15a switches on 20a circuits. :lol_hitti

klassenl · Oct 30, 2016

wyliesdiesels said:
Really? Why is that? U have a code reference that says otherwise?

BTW arguing with a licensed contractor that knows his stuff wont end well for u.

Well if I start quoting code it won't help since we live in different jurisdictions.

I have worked for 3 "licensed contractors that knows his stuff" and I have won arguments about code with all three.

I asked my inspector recently about this and he told me that switch hs to be rated for the circuit it is connected to (remember different parta of the world). I would tend to agree with him even though logic says it should be related to the load. But legal issues, liability etc.

wyliesdiesels · Oct 30, 2016

klassenl said:
Well if I start quoting code it won't help since we live in different jurisdictions.

I have worked for 3 "licensed contractors that knows his stuff" and I have won arguments about code with all three.

I asked my inspector recently about this and he told me that switch hs to be rated for the circuit it is connected to (remember different parta of the world). I would tend to agree with him even though logic says it should be related to the load. But legal issues, liability etc.

I missed the fact that youre in canada so none of this matters. US code is different than canada on this subject

pattenp · Oct 30, 2016

klassenl said:
Well if I start quoting code it won't help since we live in different jurisdictions.

I have worked for 3 "licensed contractors that knows his stuff" and I have won arguments about code with all three.

I asked my inspector recently about this and he told me that switch hs to be rated for the circuit it is connected to (remember different parta of the world). I would tend to agree with him even though logic says it should be related to the load. But legal issues, liability etc.

You should have preface your initial comment with "In Canada,".

Norcal · Oct 30, 2016

pattenp said:
You should have preface your initial comment with "In Canada,".

The CEC has no relevance in the US, and the same applies to the NEC in Canada, location is very helpful.

Speedy's comment is correct.

MikeF2316 · Oct 30, 2016

And yet, we (in Canada) buy the same lights with 9-12" of 18 gauge pigtails on them as you guys can. So that part of the circuit would have trouble with 15 A flowing through. And yet our houses don't burn down.

This is the kind of light I'm talking about:

lakeroadster · Oct 30, 2016

Speedy Petey said:
A wall switch need to be rated for the load it is controlling, NOT the size of the circuit it is on.

A 15A switch on a 20A circuit is perfectly normal.

pattenp said:
It's ok by NEC 404.14. Sized for load being switched.

wyliesdiesels said:
shhhh

I was really wanting his code reference that disallows 15a switches on 20a circuits.

Thanks.... :thumbup:

theoldwizard1 · Oct 30, 2016

It may meet code ... but it is not "logical".

Of course I put 5-20 outlets in the ends of my 12/2 - 20A circuits when I rewired the garage.

Wirepuller · Oct 30, 2016

A lot of over thinking in this forum.

Sent from my iPhone using Tapatalk

Stuart in MN · Oct 30, 2016

Wirepuller said:
A lot of over thinking in this forum.

There is no topic so minor that it can't be beat to death.

sberry · Oct 30, 2016

Not one professional thinks its a problem.

lakeroadster · Oct 30, 2016

sberry said:
Not one professional thinks its a problem.

ssbtech · Oct 31, 2016

I like the logic of sizing a switch for the load, but should the breaker not be the weakest link in the chain?

Dick in Wisconsin · Oct 31, 2016

ssbtech said:
I like the logic of sizing a switch for the load, but should the breaker not be the weakest link in the chain?

If we follow that logic and I have a single 3 amp light as the only device on a circuit, shouldn't the breaker be a 3 amp breaker?

ssbtech · Oct 31, 2016

I don't see how a 3 amp bulb could fail in such a way that it would draw more current than the wiring can handle.

If the goal of the breaker is to protect the wiring from overheating and burning down your house, putting a 20A load on a 15A light switch on a 20A circuit doesn't sound safe to me.

wyliesdiesels · Oct 31, 2016

ssbtech said:
I don't see how a 3 amp bulb could fail in such a way that it would draw more current than the wiring can handle.

If the goal of the breaker is to protect the wiring from overheating and burning down your house, putting a 20A load on a 15A light switch on a 20A circuit doesn't sound safe to me.

maybe u should write a letter to the code making panels about this.

Norcal · Oct 31, 2016

ssbtech said:
I don't see how a 3 amp bulb could fail in such a way that it would draw more current than the wiring can handle.

If the goal of the breaker is to protect the wiring from overheating and burning down your house, putting a 20A load on a 15A light switch on a 20A circuit doesn't sound safe to me.

It's not permitted to do what your saying, if the switch is sized to the load it is fine, a 15A switch w/ a 20A load is not, just because the circuit is 20A does not mean the load is 20A.

ssbtech · Oct 31, 2016

The number of people I see who have put non-dimmable CFLs on incandescent dimmer switches should give you an indication of the likelihood that people will be checking the current rating on their light switches.

In all likelihood, nobody is sticking 20A worth of lights on a 15A switch. But all it takes is some schmuck to screw in an adaptor and run a heater off a bulb socket alongside 10A of lights.

I don't know about you, but it seems to me that this is what the breaker is designed to protect against.

sberry · Oct 31, 2016

We don't put 20A loads on 15 switches. The sparky wires limited fixtures to it and some cases 15a recept Yes fixtures have smaller wire, again limited load.

sberry · Oct 31, 2016

The switch will handle it, if it fails it does but still doesn't overheat the wire in the rest of the circuit.

sberry · Oct 31, 2016

lakeroadster said:

You are an expert, its different.

jdieter · Oct 31, 2016

Doesn't this question have to be taken in the complete context of NEC wiring practices. Switches are inside approved enclosures. Branch circuit wiring in a residential setting (which I'm assuming the OP is referencing) can be installed almost anywhere in a residence. The NEC is after all a fire/safety code, i.e. branch circuit wiring laying on top of or penetrating wood structure without the correct overcurrent protection is a fire hazard. A branch circuit switch experiencing overcurrent in an approved and correctly installed enclosure would not be considered a fire hazard. But if you succumb to the paranoia change all your table lamps on 20A breakers to 12 ga. & 20 amp switches as well as all the pigtails on your lighting fixtures or install an appropriate in-line fuse at each device.

Showkey · Oct 31, 2016

As usual.............Think this thread needs two ground rods !!!!! :3gears:

sberry · Oct 31, 2016

Its a good thread, its got good stuff in it. Its a good question. My smart *** remark should be disregarded but for not one wireman or inspector wondered why. I tease lakeroadster a bit but I got a lot of respect for engineering. I didn't always but today understand someone with a mind greater than mind has figured it out ahead of me and I got to put mostly off the shelf pieces together like the pictures.

lakeroadster · Oct 31, 2016

sberry said:
You are an expert, its different.

ssbtech said:
........ But all it takes is some schmuck to screw in an adaptor and run a heater off a bulb socket alongside 10A of lights.

I don't know about you, but it seems to me that this is what the breaker is designed to protect against.

Agreed.

I changed the breaker from a 20 amp to a 15 amp. While I understand the logic, and that it meets NEC Specifications, I think it unwise for the code to allow a "weak link" other than the over current device.

sberry · Oct 31, 2016

Specifications, I think it unwise for the code to allow a "weak link" other than the over current device

Ok, you think its unwise? You really figure to be that smart and the rest of the whole industry are idiots until you happened along? None of these people know what they are doing till you wired a ,,, or had a garage wired?

Falcon67 · Oct 31, 2016

I ran all 12 AWG, my switches and outlets came in the 10 pack, cheap. I have yet to have to replace one. I only have one thing here that would fully load a 20A circuit anyway. That would be plugging in the whole 24x8.5 ft race trailer with the AC on full blast.

Radix2 · Oct 31, 2016

sberry said:
Ok, you think its unwise? You really figure to be that smart and the rest of the whole industry are idiots until you happened along? None of these people know what they are doing till you wired a ,,, or had a garage wired?

Code is a minimum. He is perfectly capable of determining where or if he would like to do more.

No different than putting in R-19 when the code says R-13.

sberry · Oct 31, 2016

I am usually trying to tell some handymans,,, don't fuk with it, I know a couple mechanical genius types, one of these days, pow or,,, the next question will be,,,, why does my little compressor??/ Or chop saw do this and the last critical info to the thread will be,,,, I screwed with the circuit after the electrician left.
I read a lot too, can write the end to a lot of stories,,,,,,,,,,,,,, but my own will probably be,,, he finally fugged up,,,, ha I try to follow the instructions, if I don't know why,,,,,, I try to follow the instructions and usually after a while I find out why I was sposed to follow the instructions.

lakeroadster · Oct 31, 2016

sberry said:
Ok, you think its unwise? You really figure to be that smart and the rest of the whole industry are idiots until you happened along? None of these people know what they are doing till you wired a ,,, or had a garage wired?

I never said anyone was an idiot... those are your words.

As a matter of fact, I even thanked the fellas for their input.

I asked a question, got a lot of answers, and did what I think is prudent.

sberry · Oct 31, 2016

You did, sorry. It really was a good question. My point being that I got to wonder if I was the only one stumbled along and thought of this? The code is well reasoned, a lot of stuff that wouldn't occurred to me and not as the system it is,,, and first thing when I get an epiphany is would they let millions of these every day be installed wrong?
@nd, it does explain in it that it is for safety and property and not a design for efficiency etc but it doesn't mean all the minimum standards arte insufficient. Lots of equipment has run a long time with a wire 2 sizes too small. The 5 hp motor, some with a 22 run, wont overheat a 12 cable.

53Sparky · Nov 6, 2016

There is NOTHING wrong with replacing the 20A breaker with a 15A breaker for your peace of mind.

As a Master Electrician with 17 years of experience in your home state of Colorado, I can say with confidence that there wouldn't have been a risk of failure if you had left the 20A breaker in, and that it is common practice for your electrician to have done that.

The question is a completely legitimate question and it was good that you asked it.

What has always bothered me more than using 15A switches on a 20A circuit is that it is also completely acceptable to use 15A receptacles on 20A circuits as long as it isn't a dedicated circuit with only one opening. That one has been tougher to figure out why it's acceptable from a logic perspective because the load isn't fixed.

MikeF2316 · Nov 6, 2016

Here's a real world example why this isn't a good idea. Back in the '80s I had a summer job at a place where the office lights were turned off at the breaker panel. Each 15 amp breaker did 9 fixtures, 4 40 watt florescent tubes per fixture. So that's 36 tubes x 40 watts = 1440 watts. 1440 watts / 120 volts = 12 amps. The lights all started tripping breakers. In our area started blowing the breaker, starting once a day, then getting more frequent. So we took a couple of tubes out, problem solved. For about a month. So a couple more tubes came out. I was there 4 months, we took out 6 tubes total. While I suspect the lamps and ballasts were drawing more current as they aged, I don't know for sure. So if these lights were on a 20 amp circuit with a 15 amp switch, they would have been using more current than the switch was designed for.

Of course in Canada, the CEC only allows 15 amp breakers for lights. Hmmm.

Speedy Petey · Nov 6, 2016

53Sparky said:
What has always bothered me more than using 15A switches on a 20A circuit is that it is also completely acceptable to use 15A receptacles on 20A circuits as long as it isn't a dedicated circuit with only one opening. That one has been tougher to figure out why it's acceptable from a logic perspective because the load isn't fixed.

Because this applies to more than one receptacles on a circuit. A duplex receptacle is TWO 15A receptacles on a single device yoke. Pretty much all 15A duplex receptacles are rated for 20A feed-thru. GFIs have this printed right on them.
"15 amp" is NOT the rating of the device, it's the rating of each of the two receptacles on the device.

bczygan · Nov 6, 2016

ssbtech said:
The number of people I see who have put non-dimmable CFLs on incandescent dimmer switches should give you an indication of the likelihood that people will be checking the current rating on their light switches.

In all likelihood, nobody is sticking 20A worth of lights on a 15A switch. But all it takes is some schmuck to screw in an adapter and run a heater off a bulb socket alongside 10A of lights.

I don't know about you, but it seems to me that this is what the breaker is designed to protect against.

Hey!.....Who you calling a schmuck? :lol_hitti

20 Amp Circuit with 15 Amp Light Switches

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