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I posted a question a few weeks ago regarding wiring to a pool sub-panel, and I'm grateful for the wonderful information I received. Since then, I learned a little more about the area between my main panel and where I need the pool subpanel.

My question is how to best wire the two based on the following:

• Main panels are in the basement. The basement is largely unfinished with a poured concrete wall about 5.5' high and with normal framing above it.


• The pool panel will be mounted outside on the same house wall as the main panel, but it will be on the other end (mains are on one side, pool panel on other side).


• I am limited to where I can exit the basement wall and cannot run the wire inside the basement all the way to where the pool panel is (on outside). I must exit the basement about halfway down that wall.


• When I exit the basement to run the wire outside, an exit through the framed part of the basement (thru plywood and siding) puts the wire on the outside about 6' above ground.


• I could exit the basement through the concrete wall and exit around 4' high.


• No matter at what height I exit, I will then need to run the wire about 3' down the outside wall and then over about 5' to get to the pool subpanel (wire needs to run ~8' on the outside).

Concerns:
I know I need the pool panel mounted chest high in order to have access to the breakers.
I think I need THWN-2 single conductors in conduit on the outside of the house from where the wires exit the house and run over to the panel.
I know I can't use THWN-2 single conductors in the house or romex in conduit outside.

So what wire do I use that's good for the inside basement run but that can also be run on the outside for a few feet? I thought it would be #6/3 romex but I also read I can't put romex in conduit on the outside.
And vice versa: if I get single strands of THHN-2/THWN-2 that are good in outside conduit, they would be an absolute pain to run inside in conduit.
I could run it immediately outside by the main panels, drop down underground, run the length of the house, then back up to the subpanel. This would be extremely difficult due to existing buried septic plumbing.

TL/DR: How do I run 60' of three conductor #6 with ground from my main panels to a pool subpanel from inside my basement, penetrating to the outside of the house (above ground), then running 8' outside to a pool subpanel (all above ground)?

Put a junction box inside the basement (i.e., right at the point where the wires exit to go outside). Romex on the inside (to make it easy to run it through the basement) and conduit on the outside (including through the wall and all the way down & around to the subpanel) with THWN. One extra box and you get the best of everything. The box does need to be accessible - can be high up on a wall or behind "stuff" but not hidden inside a wall or ceiling.

Smurf (tube) to the rescue!

As it turns out, it's legal to use ENT (smurf tube) for indoor mains-voltage conduit runs in the occupancies we deal with primarily on this site, and it has several advantages:

• It can be bent readily without tools, and ran both exposed and concealed without undue effort


• It is compatible with standard PVC bell-ends and fittings, making it possible to use ENT for benign runs and transition to PVC for outdoor work, or for damage protection using Schedule 80.


• It is widely available, with matching plastic boxes also available for use with it

In your case, your 3 6AWG THWNs, along with a 10AWG bare or THWN copper ground, will happily fit down 3/4" ENT, which can simply be mated to the bell end on a PVC stub piece, or a PVC coupling, where the conduit transitions to PVC and exists the house.