Hello everyone. I have to install a subpanel in my shed to provide electric for the inground pool I'm having installed in my backyard. I'd like it to be a 100amp panel so I have plenty of electric available for future. My main 200amp panel that'll be feeding the subpanel is in my garage and it will be a 200' run. 100' of the run will be through the garage and basement and 100' of it will be direct buried (no conduit). I was wondering if anyone knew if code for NJ would allow me to make the 200' run with a 2-2-2-4 Aluminum Quadruplex Duke URD Wire? I know I'll have a voltage drop because of the long run so I was going to make the main a 90amp breaker. I know the wire would be fine for a normal subpanel but wasn't sure if codes would be different because it's for a pool.
Aluminum Quadruplex URD Wire for Pool Subpanel
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Where will the shed be in relation to any pool equipment or the pool itself? Will you store any pool chemicals in or near the shed?
If the shed ends up being a corrosive environment (the reason for these questions) it will require you to use a copper equipment grounding conductor as well as conduit instead of direct burial.
URD isn't permitted for any indoor use if it is rated USE-2 only. Multi-rated USE-2/RHH/RHW-2 is sometimes available as URD but you have to ask for it specifically.
#2 aluminum would only be sufficient for 90A for your purposes, anyway. You're actually pretty good on voltage drop.
Thanks for the reply and all the helpful info. There won't be any pool equipment or supplies inside the shed but the filter and pumps will be located right outside the shed. The wire I was looking at is a type USE-2 cable only. Can I run it in the interior of the house if it's in conduit or is it just completely banned?
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Eh, that's a judgement call on being a corrosive environment and it could go either way. My inclination would be to say it is one. Ask your inspector beforehand. Sorry, I hate giving the 'ask your inspector' answer but it gets expensive to be wrong and I'm not there in person to see the installation.
If it is corrosive, you can use a different wiring method within the house and transition to the conduit/copper EGC where it exits the home. The newer codes developed a little bit of sanity and now only require the more stringent wiring in the actual corrosive environment. Things used to be much worse.
Completely banned. USE-2 insulation does not contain flame retardants. Have a look at MHF (mobile home feeder) cable which is allowed indoors in conduit and may be direct buried. It's available in the same quadruplex configuration you were looking at and is only a few cents more per foot than URD.
Wow OK. So it sounds like using copper is the better/safer way to go (much more expensive though). What is the most practical way to go if I wanted to use copper then? I don't want to use conduit in my basement either. Its finished and has a drop ceiling. Can I run a copper 2-2-2-6 romex type wire above the ceiling in the basement since its not easily accessible, and cover it with something where I have to strap it to the garage wall going to the main panel? Then right before I exit the house install a junction box above the ceiling and run 1 1/2" conduit through the foundation and 18" bellow ground to the shed and pull 3 separate copper 2awg wires and 1 copper 6awg wire? I don't want to half ass this but I'd love any suggestions on keeping it affordable, safe and uncomplicated. Thanks so much.
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Only the equipment grounding conductor would need to be copper and only in the corrosive portion (the outdoor part of the run). The rest can be aluminum.
2-2-2-4 aluminum SER cable would be fine for this application, even if the stricter methods are required elsewhere. This is where the new codes are helpful. Previous versions would require the conduit and copper EGC throughout the entire feeder installation. Whether or not any protection is required for SER cable on the garage wall is another subjective call.
Avoid punching through the foundation if you can. A bit of conduit and an LB visible above ground is a lot less unsightly than a basement full of water.
I would still use #2 aluminum for the circuit conductors and then use #8 copper for the equipment grounding conductor.
But first get a ruling on whether or not the conduit and copper are required at all. You may still be able to use MHF for this portion of the run.
OK I have another option that I want to put out there. I was given some wire from a friend who had it lying around that I'd like to use. I now have enough copper 1 awg and 6 awg wire that I can pull through conduit to go from the house to the 100 amp subpanel in the shed. So I'd have 100' of copper 1-1-1-6 THHN wire in conduit. Then I got a good price on 100' of aluminum 1-1-1-3 SER Service Entrance Cable Type SE Style R wire to run through the garage and basement to connect to the copper. Am I allowed to splice aluminum and copper together? I was thinking the 1 awg would work out good because of the 200' run.
You can't bury THHN in conduit. It's considered a wet environment. It needs to be THWN or dual rated THHN/THWN.
I talked with the electrical inspector today and he said I can run the 1-1-1-3 SER cable through my basement and connect it to the 1awg copper thats going through the conduit with the proper al-cu connectors. I should be all good but he said I need to use a voltage drop calculator to show how much the volts will drop do to the run. I found them online but I can't find one that will let me input half the run in aluminum and half in copper. Does anyone know of one that I can use that will allow me to enter 2 different types of wire into the same run? I know I can enter it all in aluminum to be safe but I'd rather do it showing exactly what I'm installing. Thanks for any help.
Run 2 separate calculations, one for just the partial length of AL wire you will use, and one for the partial length of copper you will use. Then, just add the 2 voltage drops together.
I think I understand what you're saying. But I'd have to adjust the starting voltage on the second half of the run to compensate for what I already lost in the first half right? So if I started at 240v and after 90' with aluminum lose 5 volts then I'd half to start the second 90' run with copper at 235 volts right?
What matters is the current running though the wire. The voltage drop will be the same whether you start at 240V or 235V.
So run both calculations with 240V. If you get a voltage drop of 3V for copper and 5V for aluminum, just add them together for a total of 8V. That will tell you that your voltage at the end of the combined run will be 240 - 8 = 232V.
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I must ask why you think you will ever need 100 amps to serve an in-ground pool?? It would be excessive since most pool areas will never need anything near that much power... ever!
It's for future. It is a big pool though with 2 - 3hp pumps and an electric heater. I will also be building a guest house in my backyard in a couple years from now which I will be tapping into this subpanel for as well. I know it sounds crazy but I don't like having to do things twice.
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OK, I got it... that makes sense now. I didn't mean to infer that you didn't know what you were doing but you must admit, without the new info you have now provided, it didn't make sense. 
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