NY_Yankees_Fan
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How many 500 Watt lights can I put on a 15 amp circuit?
Thanks
Thanks
500 Watt vs Amps?
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Anonymous Poster
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If you're talking 120 volt units, 3 easily, with a littlle power left over. You might want to turn them on individually though.
OP
NY_Yankees_Fan
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Yes 120 Volt type
OP
NY_Yankees_Fan
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What happens if you go over 1800? Do you pop the breaker?
I have 2- 500 lights ( would like to add one more 500W light), 2-150w lights+ 4-15 watt fluorescent lights plus several plugs on the same line. All are on separate switches. All run through a 20 amp GFI, all wire is 14 G.
Do you see a problem with this? Do you think the last 500W should be on another circuit?
Thanks
I have 2- 500 lights ( would like to add one more 500W light), 2-150w lights+ 4-15 watt fluorescent lights plus several plugs on the same line. All are on separate switches. All run through a 20 amp GFI, all wire is 14 G.
Do you see a problem with this? Do you think the last 500W should be on another circuit?
Thanks
ns_in_tex
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Code says you should not load a circuit more than 80% full time. You may get away with running more than 1800 watts for a short time, but if this is a continous load 80% figures 1440 watts. I personally would not worry about 1500 watts, but if more is added, you would be pushing the circuit.
Kind of like running your car at full throttle, it will take it for a while, but not as long as at a slower speed.
Kind of like running your car at full throttle, it will take it for a while, but not as long as at a slower speed.
kyoders
Silver Member
Tom,
First of all, I am not a licensed electrician, so don't take what I say as gospel. If memory serves me, 14G is too small for a 20amp breaker. I would suggest, if possible, to swap the breaker with a 15 amp (no need for GFCI if just lights), then put the 3 500 watt lights on just that circuit. You should normally only load a circuit to 80% capacity, which on a 15amp circuit would be 1440 watts, which should be close enough on lights. The suggestion about not turning on all 3 at once, like having 2 on one switch and the third on a separate switch, is a good one. Depending on the temperature and type of light, they can have a bit of a surge on startup until things come to operating temperature.
Then use your 20amp GFCI for the other circuit that has your plugs and misc. lights. Double check me on the wire size, but I believe you will want to go with 12G on a 20amp circuit. If it's not feasible to change the wiring, consider dropping down to a 15 amp breaker.
There is an added advantage to using two circuits. Say you had your lights on and the tool you were using shorted out, popping the breaker. If everything is one circuit, you are left in the dark to figure out what to do. With two circuits, at least you should have light to see what happened.
Kevin
First of all, I am not a licensed electrician, so don't take what I say as gospel. If memory serves me, 14G is too small for a 20amp breaker. I would suggest, if possible, to swap the breaker with a 15 amp (no need for GFCI if just lights), then put the 3 500 watt lights on just that circuit. You should normally only load a circuit to 80% capacity, which on a 15amp circuit would be 1440 watts, which should be close enough on lights. The suggestion about not turning on all 3 at once, like having 2 on one switch and the third on a separate switch, is a good one. Depending on the temperature and type of light, they can have a bit of a surge on startup until things come to operating temperature.
Then use your 20amp GFCI for the other circuit that has your plugs and misc. lights. Double check me on the wire size, but I believe you will want to go with 12G on a 20amp circuit. If it's not feasible to change the wiring, consider dropping down to a 15 amp breaker.
There is an added advantage to using two circuits. Say you had your lights on and the tool you were using shorted out, popping the breaker. If everything is one circuit, you are left in the dark to figure out what to do. With two circuits, at least you should have light to see what happened.
Kevin
htiek126
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kyoders is correct, you need at least 12 G wire for a 20 amp breaker and at least 14 G wire for a 15 amp breaker. Although the 14 G wire is derated and will probably work fine with the 20 amp breaker, you run the risk of having the wire fail instead of the breaker shutting off the circuit. The warmer the ambient temperature near the wire and the better insulated the area the wire, the less able the wire is to dissipate the heat, and more likely it will fail.
Phred
Veteran Member
Tom,
The other guys have probably answered your question but I will just add....
Yes if you go beyond 1800 watts or very near the breaker should trip.
I assume from your note that the 20 amp GFI is on a 15 amp breaker with 14gauge wire. If so thats fine since you are using the GFI under its rated 20 amps. If this is the case you will be fine with three lights.
I never run anything less than 12 gauge. Cost difference for personal use approaches zero. Different matter if you are doing it for a living. Although if you already have 14 ga no sense pulling out good wire.
Disclaimer: Not a real electrican, just an EE.
Fred
The other guys have probably answered your question but I will just add....
Yes if you go beyond 1800 watts or very near the breaker should trip.
I assume from your note that the 20 amp GFI is on a 15 amp breaker with 14gauge wire. If so thats fine since you are using the GFI under its rated 20 amps. If this is the case you will be fine with three lights.
I never run anything less than 12 gauge. Cost difference for personal use approaches zero. Different matter if you are doing it for a living. Although if you already have 14 ga no sense pulling out good wire.
Disclaimer: Not a real electrican, just an EE.
Fred
19th_VA
Gold Member
Yankee,
Don't know if you mentioned the GFI for a particular reason, but I just wanted to point out that GFI will not prevent you from overloading your circuit. Some people have the false impression that GFI"s will prevent circuit overloading. That is not what they are designed for. What they are designed for is preventing you from being electrocuted if you are standing in a lot of water. The GFI works by measuring the voltage through the neutral and comparing it to the hot wire. If they are not pretty close, the GFI trips. If you are standing in a large pool of water and drop a hair dryer in the water, this would allow a LOT of electricity to run into the water and YOU. The voltage would not be returning to ground through the neutral but instead through the water. If you overload a circuit the voltage returns just as it should through the neutral to ground.
In your case, you are in some danger of starting a fire because (as others have pointed out) 14 gauge wire is not the wire to use with a 20 amp circuit. The GFI will not protect you from this. I would change the breaker to 15 amp. Add another if you need more juice, rather than repulling wires. The added circuit has the benefit of separating your lighting from your receptacles, always a good idea. If I assumed wrong about your impression of what a GFI does, forgive me and disregard the first paragraph of this post.
Don't know if you mentioned the GFI for a particular reason, but I just wanted to point out that GFI will not prevent you from overloading your circuit. Some people have the false impression that GFI"s will prevent circuit overloading. That is not what they are designed for. What they are designed for is preventing you from being electrocuted if you are standing in a lot of water. The GFI works by measuring the voltage through the neutral and comparing it to the hot wire. If they are not pretty close, the GFI trips. If you are standing in a large pool of water and drop a hair dryer in the water, this would allow a LOT of electricity to run into the water and YOU. The voltage would not be returning to ground through the neutral but instead through the water. If you overload a circuit the voltage returns just as it should through the neutral to ground.
In your case, you are in some danger of starting a fire because (as others have pointed out) 14 gauge wire is not the wire to use with a 20 amp circuit. The GFI will not protect you from this. I would change the breaker to 15 amp. Add another if you need more juice, rather than repulling wires. The added circuit has the benefit of separating your lighting from your receptacles, always a good idea. If I assumed wrong about your impression of what a GFI does, forgive me and disregard the first paragraph of this post.
