I finally purchased a spa and I think I have convinced myself that it makes sense to mount the disconnect on the side of the house, running 6/3 romex inside and then using #6 THWN in PVC conduit to connect to the tub. My question today is about the disconnect. To avoid needing to use THWN back to the panel, I want to run the romex from the main panel through unfinished space , over a floating ceiling, into the exterior wall (narrow studs over concrete block). I would prefer to use all THWN, but it's $1.04/ft per conductor locally and about 50' to outside and wouldn't fit inside the exterior wall so would be more visible outside. My question is about attaching the romex to the disconnect. The one I purchased doesn't have a knockout on the back but has the space for one inside the box and I understand I can cut one. However, I am not sure how best to secure the romex to the box. I've always used the style of cable clamps that have two screws to secure the cable on the outside of the box, but I'd have to cut a pretty big hole in the concrete blocks to use this style of connector. Anyone have a better idea of how to secure a 6/3 romex cable to a wall mounted box? Thanks!

Need to use a cable connector, similar to the photo. They come in sizes up to at least 2 inch knockout, so I am sure you can find one large enough for any cable you use.

#6-3 Romex can use a 1 " two screw connector.

TK, can I mount that style of connector so the screws are inside the box instead of outside so that it fits better against the house?

Sorry, no. Concrete block is not difficult to chip away an opening large enough for the connector.

I have the cable run from the main panel, the box wired on the side of the house, and 1-1/4" conduit run to within 6" of where I intend to enter the spa's skirting (no wires in the conduit yet). The spa is in my carport waiting for a spa mover to get it into my back yard - discovered today that I don't have the right tools to make it happen.

Now that I'm very close to finished, I have two more questions that have come up. It appears that this spa was previously wired from below, as there is a hole in the floor of the under spa area near where the electrical connections are and there aren't any holes in the skirting right now. I had planned to transition to 1" liquidtight flexible conduit where my current conduit run ends to enter the tub. However, I've seen a few tubs where the standard PVC conduit goes all the way into the skirting. Since I'm so close to the spa, does it make sense to stick with rigid conduit for the last bit? I will need to run about 13' of wire inside the cabinet to reach the electrical connections. Should I be running this stretch in conduit or just as exposed (inside the skirting) THWN? Also, how should I get my 8 gauge bonding wire from the rebar in the concrete pad int the spa cabinet? Just use a cable clamp installed into the spa skirting? Thanks for your help!

I would transition to liquid-tite conduit, and not use hard conduit directly to the tub, not required, just my preference.

Does this statement, "just as exposed (inside the skirting) THWN", mean your considering running open THWN without conduit at all?

Very wrong, THWN must be installed in raceway continuously, such as conduit. THWN cannot be exposed at any point.

The bond wire needs to be spliced and extended as necessary.

So the THWN should continue inside conduit under the tub's skirting? Do I need to use liquidtight connectors on both sides where I pass through the skirting or can I just cut a large enough hole and run one piece of flexible conduit from where the rigid conduit stops all the way to the connections up front? I'd come back and caulk where the conduit enters the tub in this scenario.

I'm still confused about the bond wire. Right now, it comes out from under my concrete patio about three feet from where I'd like it to enter the tub. There's at least 20' of it exposed outside the concrete so it's plenty long enough. I'm just not sure how I should be getting it through the tub's skirting - cable clamp, just drill a little hole, or some other method.

Thanks for all your help so far TK!

Yes the THWN must be pulled through conduit, and yes, any conduit must be connected using the proper connectors.

I would like to see photos of the finished job when your done.

The ground wire can be installed without conduit under the home, where it may be exposed to physical damage outdoor it needs to be sleeved with conduit. If nothing can damage it, it can be stapled to wood framing.

TK, here's where things are right now:
http://chrispoch.com/house/IMG_3072.jpg

The spa is going to have its back side toward where the picture is taken from and will be next to the deck posts closest to the house. The bonding wire comes out from where it is connected to the rebar under the patio slab against the house in the left of the picture. You can see the rest of the wire coiled up in the grass. I'm just not sure how best to get the bonding wire into the spa's wood skirting.

I may have arrived late and you have gotten great help already. Did you check your local code about the distance from the spa to the disconnect? Also, did you talk about a Spa GFCI, maybe I missed it but that's code too

There's a 50 amp GFCI as the disconnect. It may not look like it in the picture, but the disconnect is over 5' from the patio, so I'm easily over 5' to the spa itself.

For a residential spa or hot tub, the disconnect must be no closer than five feet and within sight of the tub.

Just realized I never came back to post results and a final picture. I passed my inspection on the first try - thanks for the help! I decided to run 1" schedule 40 PVC inside the tub with 1" flex where the connection goes into the tub and at the electrical box inside the tub to play it safe. Inspector was very nice and seemed to be surprised that I had done the work.

http://chrispoch.com/house/IMG_3166.jpg

Oh sure it looks good, but does it work?

Nice job.

Yes it works very well. The heater needed some adjustments after the move (it leaked) but once I got that fixed and everything cleaned and dried out, it's been well behaved. I've been enjoying all of it except for the increase in the electric bill.

I was only kidding. I tell customers if you want it to work that will be extra.

Can you elaborate on the extra cost to run the heater? I think others would benefit by letting them know that owning a hot tub can be costly.