I will be installing a Caldera Cantabria hot tub soon and need to run the electrical from my main panel to the GFCI sub panel. I will be installing a non-GFCI 70A circuit breaker in my 200A main service panel. I will need to run the two hot wires, neutral and ground wires approximately 55-60 feet from my main service panel in the front of my basement to the side and then the back of my basement and then finally outside. I am planning on mounting the Subpanel/Disconnect box on the back of the house approximately 1-3 feet after the wires exit the basement to the outdoors. The hot tub will be at least 5 feet away from this, but probably about 6-8 feet away. It will still be within the line of sight.
I have attached a picture of the wiring diagram provided by the manufacturer. Can I use #6 wires from my main panel to my sub panel like the wiring diagram says that I can? Or does it need to be #4 wire? Also what type of wire should be used for this application? The majority of the run with be indoors in the unfinished basement ceiling area, but I will need to run the wire in conduit outside for approximately 1-3 feet.
The sub panel has 2 20A GFCI breakers and then one 30A GFCI breaker. Wiring the 2nd 20A breaker is optional, but required if you wish to use the 3rd dedicated pump for the lounge seat at the same time as the heater. I live in New England so I figured in the winter time the heater will most likely need to run at the same time as we are using the hot tub. I figured it is worth it to wire the 70A option with the 3rd breaker over the 50A wiring with 2 breakers and do it right the first time. I am planning on using copper wiring and not aluminum.
Thank you!
Best Answer
You'll need conduit for the whole run, but that means you can use 6AWG wires
You will need to run conduit for this entire run; loose wires by themselves just won't do as a wiring method (see NEC 300.3(A) for the reference on this). However, this means you can use 6AWG THHNs (/THWN, since the stuff you get these days is all dual-rated anyway) for the hots and neutral as wires in conduit can use 75°C ampacities when terminating onto suitably rated lugs (as present on all modern distribution equipment), 6AWG copper wire can handle 65A when terminated on 75°C lugs, and NEC 240.4(B) permits you to "round up" to the next higher breaker size under most circumstances we encounter here.
As to what size conduit to run? I would use 3/4" ENT through the basement run through bored holes in the joists, and then use a LB and a short length (<24") of 3/4" Schedule 80 PVC at the outdoor run to make the turn into the disconnect box. The wires exiting the disconnect, then, are run in 3/4" LFMC, using appropriate fittings at each end.