Fluorescent fixture on 20A breaker

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  #1  
Old 06-22-15, 04:21 PM
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Fluorescent fixture on 20A breaker

My garage lighting is all on a 20A branch with 12 awg wire. I have a fluorescent fixture that is hard wired, but the wiring is 14 awg. I know that there are certain, specific, exceptions to using 14 gauge on a 20A breaker, but I can't seem to find what those exceptions are.

Any help with this would be great.
 
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Old 06-22-15, 05:22 PM
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The exceptions are for motor and compressor loads. General purpose circuits with any #14 need to be 15 amps max.
 
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Old 06-22-15, 05:23 PM
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You can't find them, 'cause they aren't there. Rules are pretty staunch regarding making a fuse out of your wiring, which is what you have. It isn't that your situation is dangerous, but by code the wiring past a 20 amp breaker must be 12 gauge. Theoretically, someone could come off your fluorescent lighting and run more receptacles, exceed the load of the breaker, but would burn the wiring in some instances before it would trip the breaker, unless it was a dead short.

Edit: Yeah, I forgot about the motor stuff. Thanks, PCBoss!!
 
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Old 06-22-15, 06:11 PM
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Thanks.

So theoretically, if one were to leave said fluorescent, and didn't run anything off of it, I won't die or anything.
 
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Old 06-22-15, 06:25 PM
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You may not, but your descendents may due to your leaving a non code worthy set up trap for them, and they unknowingly use it. Theoretically.....but we can't condone theory when we know it's wrong.
 
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Old 06-22-15, 10:08 PM
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So here's where I get confused. FWIU, it's okay to put lighting fixtures on 20a circuits as long as it's not something like a dishwasher that should not have lighting on them.

210.23 (A) says it's okay to have a 15a or 20a branch circuit for lighting units. And it's pretty common that hardwired household/consumer lighting is wired with 14 gauge.

I'm also confused by this:

240.4 Protection of Conductors. Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G).

I'm sure I'm probably missing something, but I just want to get things straight.
 
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Old 06-22-15, 10:52 PM
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Outlets in a garage should have been on there own 20 amp. GFI portected circuit with 12-2 wire.
Lighting should have have been on there own 15 amp. breaker, no GFI needed.
Does not matter if the lights are wired with 12-2 as long as that circuit is protected with a 15 amp. breaker.
Back up and let everyone know how the garage was wired.
Where's it tapped into, what type and and amp's is the breaker.
Is there a sub panel?
What size wire, how long a run, how many wires?
 
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Old 06-23-15, 04:02 AM
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240.0 says it all. All wiring must be protected by the appropriate breaker. 12 gauge wiring protected by a 20 amp breaker. You can use a smaller breaker, but the larger wiring will give someone the impression it is protected by a 20 amp circuit breaker, and they will overload it. No problem as the 15 amp breaker will protect the circuit just fine. 14 gauge wiring must be protected by a 15 amp breaker.
 
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Old 06-23-15, 06:42 AM
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Wire

I have a fluorescent fixture that is hard wired, but the wiring is 14 awg.
Replace the 14 gauge wire with 12 gauge wire.
 
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Old 06-23-15, 07:03 AM
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Lighting is not required to be on a 15 amp circuit. It can be on a 20 amp circuit. It is a design issue.

The small fixture wires fall under a different set of rules since the loads are known.
 
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Old 06-23-15, 11:01 AM
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The small fixture wires fall under a different set of rules since the loads are known.
So this is where I start banging my head. If I reading this correctly, the lighting fixture is fine on the 20A circuit.

But then:

14 gauge wiring must be protected by a 15 amp breaker
The runs are all 12 gauge on 20A. It's only the actual lighting fixtures that have a smaller gauge.

If fact, the whole panel is 20A breakers except for a surge protector with a 50a double pole. All the runs, at least the ones I can get to are 12 gauge. The exception is the remaining Knob and Tube (built 1927) that serve the ceiling lights everywhere but the garage and one bathroom light.
 
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Old 06-23-15, 11:30 AM
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The wires inside the fixture are not the conductors that Article 240 and 310 are concerned with regarding ampacity. You can use the fixtures on a 20 amp circuit.
 
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Old 06-23-15, 12:02 PM
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That's what I'm looking for!

Thanks so much!!!
 
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Old 06-24-15, 09:08 AM
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seaneee - you are trying to make conclusions from numbers without understanding what those numbers mean. That 20 amp breaker could conduct more than 25 amps for up to 2 hours without tripping. That 14 AWG wire could conduct 60 amps without causing a fire. In every case, the numbers have additional perspective that gets too complex for layman.

So we dumb it down. That wire that can conduct 60 amps is called a 20 amp wire - with a large safety margin. Lamp cords are only 18 AWG (10 amps wires). And let that lamp cord will trip a 20 amp breaker long before threatening human life. We call it a 10 amp wire. But it will conduct far more than 25 amps necessary to trip a 20 amp breaker.

Those numbers do not say how much current it will conduct. Those amp numbers are simply ballpark and underrated so as to make it simple for electricians and homeowners.

Power on seven 100 watt bulbs simultanously. To a layman, 700 watts on 120 volts is only 6 amps. In reality, those bulbs may draw something less than 50 amps when powering on. Those 50 amps also will not trip a 15 or 20 amp breaker. The reasons why are more complex. So we make it simple with a sinlge ballpark number.

A 14 AWG wire was once sufficient for a 20 amp circuit. Today, that wire is only for 15 amp circuits. You need not know why - only need know the rules.
 
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Old 06-24-15, 09:26 AM
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Another major motivation for codes is that wiring in building walls (a.k.a. "premises wiring" in code lingo) is that we expect it to last a long time. Fifty years is roughly the minimum you're looking for that wiring to be safe and useful. While smaller conductors can conduct higher currents, the code factors in that we want to keep the wire operating temperatures such that the wire insulation will not degrade over very long time of daily use.

Go into an old farmhouse and take down an original ceramic light fixture and see how much of the wire insulation turns to dust or cracks off in chunks with the slightest manipulation of the wires.
 
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Old 06-24-15, 05:42 PM
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Sorry. I probably came off a bit aloof/naive with my last post. I completely get that there is way more to it than simply wiring a light. I grew up around two electricians, and a couple contractors in my family. So I know that nothing is clear cut.

My "excitement" came from someone just giving an answer, or better stated, the answer I wanted to hear. Before posting this question, I did a fair amount of research and there are two very clear opinions on the issue.
  • Fixture or not, it's technically still part of the branch, thus needs to be 12 awg.
  • Consumer lighting fixtures don't fall under the aforementioned NEC codes.

I get a bit caught up in the language of the code which points in all sorts of directions. The pertinent sections seem to be 240, 402 and specifically 410 (section covering luminaries.) I mostly get hung up on 240.5 (b)(2). There is a table covering fixture wire off branch circuits and list 20a as a minimum of 14 AWG.

Perhaps I'm reading it wrong, so feel free to correct me.
 
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Old 06-25-15, 07:58 AM
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Yeah you're on the right track. Once inside the body of the fixture, the NEC jurisdiction ends and the UL listing for the fixture begins. UL rules do permit smaller wires inside the fixture, but they are usually a higher temp rating and fully enclosed inside the metal fixture. NEC doesn't specifically require UL listing on fixtures, but there are a few lines in the 100s somewhere about all equipment being used only for intend purpose and in accordance with its listing and the manufacturer's instructions. All of that can pretty well be interpreted to only use UL listed light fixtures and to install them correctly.
 
  #18  
Old 06-25-15, 10:01 AM
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Fixture wiring is not part of the branch circuit wiring. The wiring covered by 240 stops at the fixture box.
 
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