What gauge wire do I use
Hello, I want to place a 30 amp breaker in the panel of my house and then run about 200 ft of uf-b cable to a 30 amp rv outlet that I will place near my travel trailer. I would like to have the ab...
Forum Discussion
Chum lee wrote:
I like to think of wire gauge like this. (from an engineers perspective)
With a 30 amp 120 volt circuit and a 200' run:
If you want the system to work reliably at least 80% of the time use 12 gauge copper wire. (chance of fire exists)
If you want the system to work reliably 90% of the time or more use 10 gauge copper wire. (chance of fire exists but is quite low)
If you want the system to work reliably 95% of the time or more use 8 gauge copper wire.
If you want the system to work reliably more than 99% of the time use 6 gauge copper wire.
If you want someone to come and steal your copper wire, use 4 gauge.
You don't get to decide when the system fails to work reliably. You do get to decide the chances of how reliable it will be if/when it works. It's kind of like the weather. Even if there is a 100% chance of rain, . . . it's still just a chance.
Chum lee
What are the odds for failure over an extended period? Say it's a hot day and A/C runs all day putting a heavy load on those wires. The heat builds up over time as the load increases and the chance of a failure do also. Using the proper size wire minimizes that risk potential. Where's the economy if you install a wire that's too small and burns up, then need to do the whole job over again with a larger size wire?
