Hello, I've read some of the posts on spa wiring and have a few questions about my project. I am wiring a 230V spa that is greater than 80 ft from the panel (approximately 130 ft). Because the spa normally requires 6 gauge, I assume 4 awg is appropriate for that distance so my plan is:

50 ft 4/3 THHN in the house from 50 AMP breaker in the panel to junction box on the side of the house.
80 ft 4/3 UF to GFCI 50 amp breaker within 6 ft of the tub, with an off switch mounted next to it.
Metal conduit for the house and brief runs where the UF cable goes into and comes out of the ground.
6 ft section of 6/3 from GFCI 50 amp breaker to the tub, with a metal conduit coming out of the cement where it connects to the tub

1) How does this look?
2) Will 50 amp breakers be capable of interfacing with 4 gauge?
3) Should I use another type of 4/3 other than UF and run water tight conduit the whole distance?
4) Where is the best place to buy 4/3 wire, I've had difficulty finding it online, is it best to go to a local supply place?
Thanks.

My answers are in bold:

1) How does this look?

Your plan looks fine as outlined. The #4 will help with voltage drop, and is the correct choice for this distance. Keep the service switch away from the tub at least 5 feet.

2) Will 50 amp breakers be capable of interfacing with 4 gauge?

I believe the #4 will fit in the lugs on a 50 amp breaker. Check the specs or label on the breaker, the wire size range will be listed.


3) Should I use another type of 4/3 other than UF and run water tight conduit the whole distance?

Those are your only two choices, UF or conduit. Compare prices. Conduit will allow easy future repairs or upgrades.


4) Where is the best place to buy 4/3 wire, I've had difficulty finding it online, is it best to go to a local supply place?

An electrical supply distributor may be your only hope for this cable. Check to be sure the distributor sells to the public, many, such as Graybar, will only sell to contractors.