what gauge wire?

Old 07-24-03, 02:21 PM
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what gauge wire?

I have a riding arena for training horses at home and i have come across four metal halide lights with multi-tap transformers to replace the existing lights. There are two light poles on each side of the arena. The problem is they draw 9 amps to start and 6 amps to run a 1500 watt light on a 240 volt circuit and currently only #12awg wire is laid under the arena. I'm not worried about two of the lights b/c they are within a hundred feet of the breaker box and are easy to deal with. The problem is the two lights across the arena. So the questions are...
1. It is 183ft of wire from the breaker box to the the two lights. Right now they are on the same circuit so i'm going to have to run new wire anyway to add the additional circuit. What would be the best gauge to do this with? (9 starting amps at 240)
2. Just for kicks i'll ask this question.....The existing 12awg wire runs under the arena 115ft then T's off 68 ft. in opposite directions to the two lights which are on the -same circuit-. Using 240volts wouldn't allow me to keep them on the same circuit with 12awg wire if I decreased the lights to 1000watts creating 15 starting amps correct? The distance creates too much resistance for 12awg on a 20 amp circuit, right?
Old 07-24-03, 06:46 PM
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I interpret you rdescription to mean there are two light poles on opposite sides of the arena, each to have two HID fixtures mounted. Currently there is 12 AWG wire (2 wire) running to the mid=point between the poles, and it splits both directions at that point. The circuit breaker panel is closer to the one pole which would not be too inconvenient to run a new conduit to. The farther-away pole is in question: use existing wire ore replace? And which size of wire to use for the first pole.

Since the starting current is only momentary, it can exceed the 80% load rule in the code. Two fixtures totaling 12A running on 12AWG wire at 240V would be OK. (Meaning the farther pole). I personally would use 10 AWG for new wiring, given the distance. Might it be a consideration to run 3-wire UF cable (excluding ground) or conduit with a nuetral to allow for 2 or more 120v lights should these need replacement. Conduit must be buried 18inches given it is 240v. Depending on vehicular traffic, another type of counduit or depth may be required by the NEC.

Good question.

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