Circuit Breaker/ wire load specification


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Old 07-22-04, 06:57 AM
Rich C
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Circuit Breaker/ wire load specification

Currently have 100 amp main circuit panel and want to run a separate circuit from the main to an outdoor water pond. Water pond pump max draw is 3 amps. Would like to run outdoor lighting from same circuit. What size circuit breaker and size wire would be required. (20 amp circuit breaker, 12/2 grounded wire) Distance from main panel to pump is approximately 150 feet. Should a GCFI breaker be used or can GCFI outlets be used at the circuit end. Already know about the requirements of exterior/ underground conduit. Thanks.
 
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Old 07-22-04, 09:16 AM
J
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What size circuit breaker and size wire would be required. (20 amp circuit breaker, 12/2 grounded wire)
Is that a proposal, or were you answering your own question? Although we know that the pump will be 150 feet away, how far away will the lights be? Will the lights be out there by the pump? And what is the total wattage of lights involved?

Should a GCFI breaker be used or can GCFI outlets be used at the circuit end
I'd recommend neither. I'd use a regular breaker and a GFCI receptacle inside the house.

Already know about the requirements of exterior/ underground conduit
Conduit may or may not be required. But wet-rated wiring (THWN or UF-B) is definitely required in either case. What kind of conduit and what burial depth are you planning?
 
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Old 07-23-04, 01:15 PM
Rich C
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Originally Posted by John Nelson
Is that a proposal, or were you answering your own question? Although we know that the pump will be 150 feet away, how far away will the lights be? Will the lights be out there by the pump? And what is the total wattage of lights involved?

I'd recommend neither. I'd use a regular breaker and a GFCI receptacle inside the house.

Conduit may or may not be required. But wet-rated wiring (THWN or UF-B) is definitely required in either case. What kind of conduit and what burial depth are you planning?
It was an example; the lights will be in the area of the pump + max 100 ft, low voltage decorative lights with 2 to 3 120W transformers.

What size regular breaker would you use, and if you use a GFCI breaker inside, how would you attach the outside wiring to the GFCi receptacle?
I was going to use 12-2 UF-B inside PVC piping at depth of 12". (Over kill?) Are simpler alternatives available?
thanks.
 
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Old 07-23-04, 02:46 PM
J
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I still need to know the total wattage of the lights. I can't get that from the wattage rating of the transformer.
 
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Old 07-24-04, 03:06 PM
Rich C
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The total wattage is 800 watts.
 
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Old 07-24-04, 03:59 PM
J
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800 watts of lights will draw about 7 amps. The pump draws another 3. So the first 100 feet of the cable will carry 10 amps, and the last 50 feet will carry 3 amps. If you use #12 copper wire, that will lose about 3.4 volts over the first 100 feet and another 0.5 volts over the last 50 feet. So 116 volts of the original 120 volts will make it out to the pump, even when all the lights are on. This is reasonable, so #12 will do fine (as long as you never add any more load to this cable).

So I'd just use a 20-amp breaker and 12/2 NM-B cable out of the panel. Before you leave the house, run it through a GFCI receptacle to provide protection. But don't plan to plug much into that receptacle--it's not there for you to use, but only to provide GFCI protection more cheaply than a GFCI breaker. Then run 12/2 UF-B cable out of the load side of the GFCI. Run it though 3/4" PVC conduit when going through the wall, and until it reaches the bottom of the trench, and any place else it will be above ground. Dig a trench at least 12 inches deep, and make sure there are no rocks that might damage the cable when you fill it back up.

If you think you might add more loads in the future, or you would just like to extend your pump life a bit longer, you might decide to run 10/2 rather than 12/2.
 
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Old 07-25-04, 06:17 AM
Rich C
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Smile

Thank you very much for the information and assistance. I'll drop a line to inform you how the project turns out!
 
 

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