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First things first, thank you to all who are willing to share their experience and knowledge here. I need some advice and or reassurance that I am planning this system correctly. I am going to be running a 60 amp pool panel (Intermatic PE25300F) from a subpanel in a detached garage. The subpanel in the garage is now good to go (70 amp, three wire with ground, two ground rods) thanks to the advice from this forum. Here is the link to my previous post getting that panel up to code. (subpanel wiring after upgrading feeder wire).

The only items that will be ran from the pool panel is a 1.5hp pump, pool light, and maybe some landscape lights down the road. Well below the 60amp rating. The garage subpanel only has one heavy load which is a 240v wall heater on a 30 amp breaker, other than that its just lights and plugs (the other 240v 30amp breaker in the picture was a water heater that no longer is there).

It is my understanding that any # of sub panels can be pulled off another subpanel as long as they step down and cant "overdraw" the previous (at least during the same season/use schedule). Also to run a pool panel from a subpanel it can not have NM cable anywhere on the line, so the insulated ground has to be carried all the way through. The garage panel is inside the garage and I would like to run the wire through the garage and directly out the wall into the pool panel. If this is the case and I understand correctly, to feed that panel, I would need to use THHN wire and that must be in continuous conduit from panel to panel even if ran indoors. Is this correct? Am I going about this all wrong or missing anything?

So quick version - How do I wire a detached garage subpanel, through the inside, and directly through the exterior wall into a pool panel flush mounted on the outside of the garage.

FYI - I will have an electrician come out to look over everything in the end. I cant afford to not do as much as I can myself, I can however afford to have a pro make sure everything is safe before use. I will do my best to keep up and respond to any follow up questions. Thanks again!

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All of your questions you have the correct answers, thhn is dual rated thwn so it can be used in conduit both inside and outside as required.

You do need an insulated ground. You can put in a 100 amp panel at the pool and feed it with a 30 amp breaker or the size you want .

the 1.5 hp 240 v motor is rated at 6 amps + 25% (motors require 125% of the FLA book values).

I think you are on your way if you wanted another sub past the pool sub that is a sub in the garage fed from the house it is ok. As a detached area another rod would be needed for this sub.

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  • Great, thank you for the quick answer. So on the last part you mentioned, I thought the pool panel would require two ground rods the same as the subpanel because it is outside and a separate sub? Are you saying that would only be required if I pulled a subpanel from the pool panel? – Jay Feb 5 at 23:12
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    My jurisdiction only requires 1 . It is always a good thing to have plenty of ground electrodes and it’s only a few bucks. – Ed Beal Feb 5 at 23:27
  • Great, I will stick to my plan to use 2. Thanks again! – Jay Feb 6 at 0:03
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    Does the sub really need its own ground rods if it's attached to the garage? Ir is the garage missing them? + on "no such thing as too many" – Harper - Reinstate Monica Feb 6 at 4:24
  • I thought the op said the pool panel was separate from the garage., but after re reading it is attached to the garage so no ground is required for the panel. – Ed Beal Feb 6 at 14:23
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Your pool subpanel mounts on the side of the garage, so it doesn't have any underground runs. There's disagreement as to whether NM cable is allowed to "stick its nose outside" to service a panel mounted on an exterior surface; but no question of either UF stapled, or THHN/THWN-2 dual-rated wires in conduit.

Wires from the subpanel toward the pool need to be in conduit (or direct burial rated MC) due to NEC 680.11 (thank you ThreePhaseEel). If you use RMC or IMC conduit, your burial depth need only be 8" (for 6" of cover, the stuff is expensive as blazes but you can do your trenching with a garden trowel.

THHN wire needs to be entirely inside conduit, that is true. You can make the subpanel to sub-subpanel run in conduit if you really want to, but since you're not venturing underground or outside (barely), I wouldn't sweat it.

Lastly, if an electrician is to be involved, that's a huge argument in favor of conduit all the way. Conduit is, to be frank, 80% of the work. Slapping wires in pre-existing conduit is pretty easy if the conduit work is done right.

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  • UF can't be used here as NEC 680.11 forbids it -- he has to use RMC, IMC, PVC, or jacketed MC; out of those, PVC's probably the easiest choice – ThreePhaseEel Feb 6 at 2:58
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    Thanks @ThreePhaseEel. Turns out I latched onto UF while reading the question, then forgot the subpanel run doesn't actually leave the garage since it's mounted on the wall of the garage. – Harper - Reinstate Monica Feb 6 at 4:20
  • Hey everyone, thanks for the replies and sorry for my delay in responding. So your saying there is a way to run power to that panel without running conduit through my garage?... I would rather do it once and not cut any corners unless I am missing a option, obviously running just wire would be way easier! "THHN wire needs to be entirely inside conduit, that is true. You can make the subpanel to sub-subpanel run in conduit if you really want to, but since you're not venturing underground or outside (barely), I wouldn't sweat it." – Jay Feb 7 at 1:41
  • I thought THHN had to be in conduit anywhere it went because of the fire rating of the sheathing or something? – Jay Feb 7 at 1:46
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    If the pool panel is hanging on the outside wall of the garage, with the feeder coming in from inside, then 680.11 doesn't apply (it's about underground wiring around pools), nor does 680.25(B) about feeders in corrosive environments (at least, as of 2017 Code). – ThreePhaseEel Feb 7 at 2:15

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