I am remodeling my kitchen and I added a dimmer switch to an existing circuit. I have a live wire entering the dimmer switch and my wire exiting the dimmer switch is taped off on the end and not connected to anything. This setup is temporary until I install new lighting fixtures that will be controlled by the dimmer switch.
PROBLEM: Yesterday, my son accidentally turned the dimmer switch ON and after 12 hours, the 20-amp circuit breaker tripped. I repeatedly tried to reset the breaker but it immediately shut off. Then I turned the dimmer switch OFF and was able to turn the breaker back on successfully. I assume that there is a ground fault somewhere- probably at the end of the wire I taped? Could it be something else? When adding a new switch to an existing circuit, do you need another wire looping back from the lights to the dimmer switch?
Finally, the wire for the 20-amp circuit is 12/2 NMB. For my lighting extension, I used 14/2 NMB because the draw would only be for lighting and low wattage devices. Is this o.k. or do I need to rewire the entire thing with 12/2? My refrigerator is connected to the circuit but it’s connection is all 12/2 from the breaker box to the appliance.
Any help will be greatly appreciated, especially by my wife who’s rapidly loosing confidence in my DIY abilities.
– Lyptus
Replies
I'm sure there will be a few others that will chime into this. First off, on a 20 amp circuit ALL wiring must be 12 gauge. This is not plumbing where you can start with a large pipe and branch off smaller pipes. If there is a problem with the fixture the 14 gauge wire could overheat and start a fire before the breaker would trip.
When you say you taped off the wire. That made me uncomfortable. I would have used a wire nut or, better still, cut off the stripped end and folded it back on itself and taped that. I suspect that is what causing the breaker to trip. This might just be me, but if a circuit trips and I reset it and it trips again I don't try anymore until I locate the problem or at least let thing cool off.
The refrigerator and lights should be on separate circuits.
Lots of problems here.
First you can't down size wire. While it may be enough to feed a light there is always the concern that the circuit gets extended some more and a large load is put on it.
"My refrigerator is connected to the circuit but it's connection is all 12/2 from the breaker box to the appliance."
The kitchen small appliance circuits are not suppose to have any lighting on it. Although if the refigerator is the only receptacle on that circuit then it might be argued that it is not a small appliacne circuit. But in anycase undercounter lights have been run off the small appliance circuits once or twice in the past.
"Could it be something else? When adding a new switch to an existing circuit, do you need another wire looping back from the lights to the dimmer switch?Could it be something else? When adding a new switch to an existing circuit, do you need another wire looping back from the lights to the dimmer switch?"
First of all ALL wiring should have a pair of wires in every conduit or cable so that the current is balanced at all times. IT can be in several combinations Supply and return, Switch supply and return, or supply and switched supply for a switch leg from a fixture.
Is this a "plain breaker" or one that includes a GFCI function (does it have a test button?).
"I have a live wire entering the dimmer switch and my wire exiting the dimmer switch is taped off on the end and not connected to anything."
If only one wire of the dimmer is connected then it can't be the problem.
More likely I would look carefully at all of the connections and at the cables and wires for any cut insulation. One common problem area are staples that are driven to tight or the metal romex connectors that are tightened too much and cut the insulation.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
"First you can't down size wire. While it may be enough to feed a light there is always the concern that the circuit gets extended some more and a large load is put on it."
Now, warnt it you that told me once it was OK to run 14/2 from a switch on a 20A line directly to a single light fixture? I could swear you said there was a code exception for this. Like it's OK to use 15A outlets on a 20A line if there are more than one. But mebby I'm just dreaming it.
Mike HennessyPittsburgh, PA
Never mind -- I just read one of your follow-up posts.
Edited 12/27/2007 1:23 pm ET by MikeHennessy
I disclaim making any such statments..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I am not an electrician and I am sure you will get one of the regulars experts chiming in soon. It sounds like you could have bare/grounded wire. Not sure how some of the dimmers will react if not completely hooked up as designed and then turned on, that could be the problem also.
The 20 amp breaker circuit should have nothing but 12ga on it with the exception of wires built-in to fixtures/appliances. IF your 14ga wire shorted it could smoke something before the 20 amb breaker might react.
Again, not an electrician, and did not stay at Holiday Inn Express last night. Suggest you get one of the boks for diy wiring, Stanley has one and there are many simple ones out there, otherwise your wife may be right(:-).
"The 20 amp breaker circuit should have nothing but 12ga on it with the exception of wires built-in to fixtures/appliances. IF your 14ga wire shorted it could smoke something before the 20 amb breaker might react."The problem is not SHORTS, but rather small overloads that are within the rating of the breaker.A short will quickly trip the breaker. And for use with DEDICATED motor and AC circuits you can have breakers larger than you can have on general purpose circuits. In thos cases the breaker only needs to protect the wire from damage from a short..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I should have said overloads. Would not a shorted 14ga possibly get hot enough to cause a problem before the 20amp tripped? If it was only overloads then why can't we still use 14 for a switch leg serving only one stinking light?
Also I said "The 20 amp circuit", not "a 20 amp circuit" meaning his multi use, refrig, and who knows what on it which is not a dedicated motor/ac one.
I only posted to get you in there (;-). Happy New Year!
"If it was only overloads then why can't we still use 14 for a switch leg serving only one stinking light?"Actually that would be safe.But while complex, the code does a trade off trying to have a few basic requirments rather than have a thousand design rules. So smaller guage on switch legs is lot allowed, although you can use a switch that is sized to the load, not the circuit capacity.My guess is that one of the differences is that the switch can easly be changed if needed, but the wiring can't.But that like might be replaced with a blank coverplate and the switch leg used to feed power to something else in the future.However, there are several plaes where tap rules are allowed.One is for builtin cooktops and ovens. You can run one circuit sized for the combined load. Then have taps that run to each device. The taps are sized to the size of the individual loads.And as I mentioned earlier, dedicated motor and AC circuits use completely different rules to size the wires and breakers. Under those rules it would not be uncommon to #12 wire with 25, 30 or even 35 amp breakers.Common residential branch circuit breakers have a dual trip. One use a heating element and bi-metalic trip. That is used for small overloads. It is time inverse in that the larger overload the faster it trips. A small overload can take several minutes to trip.The 2nd part is magnetic. It is use a soleniod. It starts at about 8-10 times rated current and trips within a cycle or less. That is what works when you have a short.On dedicated motor/AC circuits the device or controller has overload protection for the motor. And since the circuit is dedicated you won't be plugging in other devices. So the breaker only needs to protect against shorts and it can be much larger than nominal for that size wire..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I agree on the safety of the discussed 14ga switch leg but I believe it is still not legal. If there is a way to screw something up somebody will surely find it. When we did my house we ran 12 to switch box and then 14-3 up for switch legs. I think one or two are still on a 20 amp and probably should go put 15s in.
I was not arguing the other stuff, or any of it for that matter. (:-)
So, to sum up... I must replace all the 14/2 wires attached to the the 20-amp circuit with 12/2 wire. Also, I must check for shorts at box connections and where staples secure the wires to the studs and joists. Because the breaker only trips when I turn on the new dimmer switch, doesn't that mean the short must be somewhere between the dimmer switch and the unconnected 14/2 wire extending out of the dimmer switch (the one with the taped end)?- Lyptus
"Because the breaker only trips when I turn on the new dimmer switch...' This seems like a logical deduction. Black phase tape is good for 600 volts.
A GF breaker will trip with very little current. Does the breaker trip instantaneously or does it take a while? If it trips as soon as you turn it on, that would be a dead short. If it takes several minutes, then it would be tripping on an overload. If a GF breaker trips instantaneous, it could be either a dead short or a slight ground fault. Swap the GF breaker temporarily with a standard one to tell the difference.
~Peter, the smut detector
To replace all the 14ga wires is a pain. To be safe and code compliant, just change the breaker to 15A. That is, if you don't REALLY NEED the 20A circuit.
Then, since the breaker trips only when you activate the new dimmer, the first thing you do is remove the dimmer from the equation and cap the feed.
This step should determine if the switch is the fault.
So, to sum up... I must replace all the 14/2 wires attached to the the 20-amp circuit with 12/2 wire.
The National Electric Code requires that the kitchen small appliance circuits not have any lighting on them, as Bill already said. (Section 210.52(B)(2)).
So if you wish to follow the NEC then you should tap your new lighting outlet from a lighting or general use circuit.
Ed
A refrigerator is not a small appliance. Its outlet is not required to be on one of the small appliance circuits. As I understand it.
Its outlet is not required to be on one of the small appliance circuits.
Yeah it is, with one exception, and the OP's situation does not meet that exception.
"210.52(B)(1): In the kitchen, pantry, breakfast room, dining room, or similiar area of a dwelling unit, the two or more 20a-amp small-appliance branch circuits required by 210.11(C)(1) shall serve all receptacle outlets covered by 210.52(A) and (C) and receptacle outlets for refrigeration equipment".
There is an exception for a dedicated line to the refrigerator, 15a, that can have no other outlets on it, lighting or otherwise.
The operative word here is "shall". "Shall" meaning that it is mandatory.
Ed
Edited 12/28/2007 4:45 pm ET by edlee
Thank you all for your help. I found the short. I had miswired the dimmer switch- connecting both black and white incoming and outgoing wires to the two black wire connectors on the switch. I corrected the problem by tying off the white wires together and only connecting the black incoming and outgoing wires to the switch. Duh.
I also replaced the 14-gauge wire I added to the 20amp circuit with 12-gauge wire and moved the dimmer switch to a living room living circuit.
Thanks for your help!
- Lyptus