What wire gauge should I use

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Mitch murray

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I am running lights that will have a 500 ft run length and have six 700 watt lights spaced evenly space. Can I use 10 gauge wire the entire length?
 

Jadnashua

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What voltage? 500' of 10g wire has an average resistance of 0.5-ohms, which will reduce the voltage a bit at the end, but it depends on the voltage you start with.
 

Reach4

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At 240 volts, you would be fine I think if the fixtures are wired in. I don't know about the use of outlets. It is not OK for 120 volts.
 

Speedy Petey

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I am running lights that will have a 500 ft run length and have six 700 watt lights spaced evenly space. Can I use 10 gauge wire the entire length?
Even at 240V #10 is not even close to big enough.

You need to tell us more about this project. What kind of lights? Voltage? Actual length of everything?
 

Reach4

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Good point. 1000 ft of wire would be about 1 ohm.

As an estimate, if we presumed (for easy calculation) the fixtures would each draw 2.9167 amps and the 6 segments of wire were the same length with 1/6 ohms per pair, the last fixture would see about a 10.21 volt drop. That would be the sum of the drops on the 6 segments. For each segment, the respective drop goes
2.92V, 2.43V, 1.94V, 1.46V, 0.97V, 0.49V. (which total 10.21V)

This is not to say that this calculation corresponds to good electrical practice. This calculation was just a math exercise that takes some simplifying assumptions.
 
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Mitch murray

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I am putting work lights on poles to light up an arena. So they are the halegen double bulb work light. I have 240 going to the arena and I'm actually running 6 lights on one side and six on the other. I have 6 up and running on one side and they are good but now I'm trying to install the other side.
 

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I am putting work lights on poles to light up an arena. So they are the halegen double bulb work light. I have 240 going to the arena and I'm actually running 6 lights on one side and six on the other. I have 6 up and running on one side and they are good but now I'm trying to install the other side.
Can you do other than halogen?? Incandescent is so bloody inefficient. HID or LED would be FAR less wattage for the same light output so voltage drop will be much less of an issue.
Also, where are you finding 700 watt halogens? Never heard of them.

Since this is simply incandescent lighting it is more resistant to voltage drop. Best practice would be to use #4cu conductors for the full load. You could get away with smaller depending on the actual load.

What did you run to the first half of the lights? Now you are running a complete new feed to the rest?
 

Mitch murray

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Can you do other than halogen?? Incandescent is so bloody inefficient. HID or LED would be FAR less wattage for the same light output so voltage drop will be much less of an issue.
Also, where are you finding 700 watt halogens? Never heard of them.

Since this is simply incandescent lighting it is more resistant to voltage drop. Best practice would be to use #4cu conductors for the full load. You could get away with smaller depending on the actual load.

What did you run to the first half of the lights? Now you are running a complete new feed to the rest?
Its a two bulb light fixture so 500 for one and 200 for the other. I'm on a tight budget and those lights were 20.00 a piece. I have #6 wire feeding 240 to a breaker box and one set will run off of one side and the other will run off of the other side in the breaker box
 

Mitch murray

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Its a two bulb light fixture so 500 for one and 200 for the other. I'm on a tight budget and those lights were 20.00 a piece. I have #6 wire feeding 240 to a breaker box and one set will run off of one side and the other will run off of the other side in the breaker box
I am running six fixture on 10 gauge right now and they seem to be working fine. The other run is twice as long though and that is my worry
 

Jadnashua

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Because of the wire's resistance, at higher loads, it acts like a heating element...it might work, but may have issues in the middle of summer during a heat wave when the wires can't cool by radiation like they can in the winter. THe wire has a heat rating, and depending on how they are run (overhead, underground, through a conduit, etc.) all affect how well they can dissipate heat and how much the circuit must be derated to be proper and safe, which is why I asked way back about what voltage, since 120vac circuit would take twice the amps of a 240vac circuit.
 

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Because of the wire's resistance, at higher loads, it acts like a heating element...it might work, but may have issues in the middle of summer during a heat wave when the wires can't cool by radiation like they can in the winter. THe wire has a heat rating, and depending on how they are run (overhead, underground, through a conduit, etc.) all affect how well they can dissipate heat and how much the circuit must be derated to be proper and safe, which is why I asked way back about what voltage, since 120vac circuit would take twice the amps of a 240vac circuit.
Sorry to keep asking about this. So if I have a 240 circuit breaker box and I run 3 lights off of each circuit the longest run being 500 ft half in conduit underground and the other half in the pipe fence rail. I'm using thhn 10 gauge wire the whole way. It's outside and never touches anything that wil catch fire and run only at night but I do live in Arizona. Do you think that it is adequate? Or am I pushing the limits?
 

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What amperage cb are you using? 10G can handle a max of 30A. Your load would not pass with a 20A circuit, even though your load isn't 20A...code says no more than 80% load for a continuous use.

Three lamps at 700W each, 2100W/240v=8.75A. E=I*r, so 8.75*0.5=4.375v drop at the end. power=amps*volts, so 8.75*4.375=~38W, so you'll be losing about 38W in heat in the cable. Depends, that's probably not enough to be dangerous. I do not know what the code says about this.
 

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Voltage drop in the code is only a suggestion for best performance. It is NOT code required to counter it.

With incandescent lights they will simply be dimmer at the long end. If you go with smaller wire, like #10, then DO NOT us this line for receptacles or any other lighting than incandescent.
 

WorthFlorida

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I am putting work lights on poles to light up an arena. So they are the halegen double bulb work light. I have 240 going to the arena and I'm actually running 6 lights on one side and six on the other. I have 6 up and running on one side and they are good but now I'm trying to install the other side.

If this is a commercial site used as a place for the general public or a work place you better have your permit in order with an approved design (shatter proof, etc.) for such lights. Otherwise your in a dangerous area and there is alway the insurance issue should a problem arise. Metal halide lamps of about 175 watts will give off more light and last much longer than most lamps. It does take a far different fixture to hold a ballast and capacitor. If your set up is approved then you should have two circuits and separate run for each side. Should a breaker trip then at least half the lights are working instead of being totally in the dark.
 
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