Homeowner installing electric to hot tub

[Watson524]

Hi all,

We just purchased a hot tub and are now waiting for it to come in and planning out the electrical. We currently have a 200a main panel. In that there's a 50a/double pole breaker feeding a subpanel directly underneath it with #6 AWG wire. The subpanel has a 60a transfer switch in it (not a true transfer switch, it's 2 60a double pole breakers with a plate connecting them so you can never have both on at the same time and backfeed into the power line) so that when we lose power, we can plug the #8 rubber cord into the portable generator (that can support up to 46a per the plate on it) and switch manually between power company power and generator power. The subpanel has the well, hot water oil boiler with 5 zones (limited pull from circ pumps at 1/25hp each), fridge, microwave and some random rooms with lights/outlets. I'm going to assume the 60a switch in the subpanel is really just a "pass through" and we're only getting a max of 50a to the panel because of the 50a breaker feeding it in the main panel. We don't really have zoning or inspections around here for this sort of thing and plan to do the work ourselves (tho to protect our warranty, I'd likely have an electrician friend check the work before we hook up to the tub when he's in town).

I know with the hot tub I need a 60a breaker in the panel in the house and then a 60a gfci in the "spa panel" outside no less than 5' and no more than 20' from the hot tub. My plan is to run 4 color coded #6 AWG wires from the house panel to the spa panel and then since we don't need a neutral in the tub, 3 - #6 AWG from the spa panel to the tub itself. Figure I'll use 1" sch 40 PVC and run it along the sill plate in the unfinished basement and out the siding under the deck, go along a main beam of the deck to the spa panel that'll be mounted on a leg of the deck and then bury the conduit from the spa panel to the tub, stub up at the tub and then run it in flex liquid tight from one side of the tub to the hook up area.

In our main panel, we have no more room for breakers, in the subpanel, I have 2 (on the same phase so I know I'd need to move a breaker over to be able to install a double pole). We often get power outages and I want to be able to run the heater and circ pump (total of about 23a) off the generator if the power outage is long. I know I'd need to likely not have other things running at the same time off the generator because it'd be too much for the generator to handle but that's not a big deal. When power's out we're conservative anyway.

In order to be able to feed more power to the subpanel, can I change the 50a double pole to say an 80a one (assuming Square D QO come like that) and then the same in the subpanel (or even 100a) and carry on that way? If I've done my load calcs correctly for the sum of the VA for all the appliances + square feet of the house / 3 for "random" VA and then converted to amps, I'm coming up at about 162a total for the house with the new hot tub on it so my guess is I'd be fine but wanted to double check.

Also - if I did go to an 80a breaker (or 100 if square D don't come in 80) is the #6 AWG wire that's between the main and subpanel now ok?

Thanks in advance!

 

[Watson524]

Since it's likely relevant re: what breakers are available, the main panel in the house is Square D Homeline and the subpanel is Square D QO

And what just occurred to me that may affect this is if I upgrade the main panel breaker that feeds the subpanel to 80a, I still can't draw more than 80a off that subpanel even when running from the power company power right? Because I'm only pushing 80 into it. So that may throw a wrench in things when I want to run the hot tub normally under normal conditions (drawing about 48 - 50a) and then want to use say my boiler, refrigerator and other things on the subpanel.

 

[Sponsor]

 

[hj]

YOu should NEVER be able to "draw" more current than the rating of the circuit breaker, regardless of what sizes you have before or after it. And, the smallest breaker on the circuit will determine the maximum load for THAT circuit.

 

[Watson524]

ok that's what i thought. so the lower amp breaker on the generator itself really would be the limit there if it was hooked up to the breaker and 100a or 80a in the main panel would be ok.

Tho, I've decided to not worry about the tub on the generator and just do the normal wiring and if there's a cold snap put a light bulb in the cabinet if need be and if it gets really bad with a power outage, i can just drain it and blow the lines out

 

[PatrickH]

You should be careful about loading up the sub panel fed by the generator. It's likely size to accommodate the generator you have. Use watts= voltage * current to perform a sanity check on adding the circuit. You may be able to double up some of the single pole breakers in the main panel using piggy back breakers, and ad the feed for your hot tub there. Just be careful not to share a neutral with two circuits on the same piggyback. Also, if the over current breaker in the sub panel is 60 amperes, then changing the main panel breaker to 80 amperes will not give you 30 additional amperes. The sub panel breaker would trip at 60 amperes. Also need to consider the current rating of the panel itself. May want to soak in the hot tub after the power outage.