100 amp sub panel
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wwhitney
In the Trades
That's the wrong wire for a standard 120/240V subpanel. You need 4 conductors--two hots, a neutral, and an EGC (which may be bare). You have only 3 conductors, two insulated and the segmented bare conductor, which can be the EGC. So you could use it for a 120V only subpanel, or a 240V subpanel, but not a 120/240V subpanel.
For a 120/240V 100A subpanel, I'd suggest 2-2-2-4 Al SER cable supplied by a 90A breaker, or 1-1-1-3 Al SER cable supplied by a 100A breaker.
To answer your question, the bare wire around the outside of the two insulated conductors is the third conductor, when you strip the outer sheath off, you can gather the exposed portion together and twist it into a bare stranded conductor.
Cheers, Wayne
For a 120/240V 100A subpanel, I'd suggest 2-2-2-4 Al SER cable supplied by a 90A breaker, or 1-1-1-3 Al SER cable supplied by a 100A breaker.
To answer your question, the bare wire around the outside of the two insulated conductors is the third conductor, when you strip the outer sheath off, you can gather the exposed portion together and twist it into a bare stranded conductor.
Cheers, Wayne
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Wayne it is only going be 120 only. Deep freeze etc. Some outlets and lights.thank you
wwhitney
In the Trades
OK, you can use your cable for a 120V only panel, it will just have half the capacity versus having the extra conductor in your cable. You'll use the bare as EGC, label one of the insulated white and use it for the neutral, and use the other insulated for your hot. You can supply the cable with a 100A breaker, but the breaker will presumably be double pole and you'll only use one of the two lugs for your single hot.
On the subpanel you can either just land the hot on one of the two lugs and only use half of the spaces (you'll need to figure out which one). Or you can get a 3-port Polaris style connector so that you can run jumpers to both lugs from your single incoming hot conductor. In which case you would be wise to prominently label the panel "120V only, no multi-wire branch circuits".
Basically, it will all work, it will just be very unusual. You are probably better off getting the typical cable with the additional insulated conductor and installing things normally.
Is this subpanel in the same building as the originating panel, or is it in a detached structure? For the latter, you need to install a grounding electrode system at the detached structure.
Cheers, Wayne
On the subpanel you can either just land the hot on one of the two lugs and only use half of the spaces (you'll need to figure out which one). Or you can get a 3-port Polaris style connector so that you can run jumpers to both lugs from your single incoming hot conductor. In which case you would be wise to prominently label the panel "120V only, no multi-wire branch circuits".
Basically, it will all work, it will just be very unusual. You are probably better off getting the typical cable with the additional insulated conductor and installing things normally.
Is this subpanel in the same building as the originating panel, or is it in a detached structure? For the latter, you need to install a grounding electrode system at the detached structure.
Cheers, Wayne
wwhitney
In the Trades
I can't advise you without more information. Where is the source panel? Where is the subpanel? What is this conduit you are referring to? What size is it, is it a complete run between panels, etc?
Cheers, Wayne
Cheers, Wayne
My 2 cents here.
I would instead install a 60 amp 240 v sub panel instead and run #6 THWN in conduit. That would give you 20% more capacity than a 100 a 120 v supply (2 x 60 Amps) #6 stranded copper is a lot easier to pull than your aluminum. Easily available at either Lowe’s or Home Depot custom cut to your desired length. If run is not longer than 75 feet you would be OK with 6 AWG THWN.
If it’s in a different building than at the main panel you would need a main shutoff at the sub panel location and grounding rods.
Here’s a picture of my 60 amp sub at my barn/shed just after it was installed and before the 60 amp 240 v top left breaker was labeled as “MAIN”
I would instead install a 60 amp 240 v sub panel instead and run #6 THWN in conduit. That would give you 20% more capacity than a 100 a 120 v supply (2 x 60 Amps) #6 stranded copper is a lot easier to pull than your aluminum. Easily available at either Lowe’s or Home Depot custom cut to your desired length. If run is not longer than 75 feet you would be OK with 6 AWG THWN.
If it’s in a different building than at the main panel you would need a main shutoff at the sub panel location and grounding rods.
Here’s a picture of my 60 amp sub at my barn/shed just after it was installed and before the 60 amp 240 v top left breaker was labeled as “MAIN”
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wwhitney
In the Trades
OK, I take that to mean a detached garage, and that the PVC will be underground. Then a couple points:
- You definitely need a grounding electrode system at the garage.
- Type SE cable is prohibited underground, so you can't use that cable.
Since you're going to install a complete PVC conduit system from panel to panel (maximum 360 degrees of bend between pull points), you're better off pulling individual wires (THWN) through the conduit. If you want a full 100A feeder (may be overkill for the loads), then you'd need to use #3 Cu or #1 Al circuit conductors, and a #8 Cu or #6 Al EGC. For a 60A feeder, you could use #6 Cu or #4 Al circuit conductors, with a #10 Cu or #8 Al EGC. You might as well pull 3 circuit conductors for a 120/240V feeder.
Conduit sizing is another question, you can look up a calculator to get the minimum size.
Cheers, Wayne
P.S. Zooming in on the photo, that cable says 2 AWG Al, not 2/0 AWG. So it is too small for a 100A feeder, maximum would be 90A.
Very similar to my setup but the distance is only 75 feet. I have 4 #6 copper THWN wires in PVC conduit. When my 240v 30 amp electric car charger, 5000 btu Window unit, lights and well pump runs I get less than a 2% voltage drop. That at max 48 amps Per leg.
With a 100 ft run with #6 THWN @ full 60 amps per leg you would still have less than a 3% voltage drop.
Separate building requires ground rods at sub panel and separate shut off by or at sub panel. I pounded in 2 ea 8’ ground rods and ran #6 solid from sub panel ground buss to the 2 ground rods.
I bought this sub panel kit https://www.lowes.com/pd/Eaton-Cutl...t-Main-Breaker-Load-Center-Value-Pack/3047149 replaced the 100 a main breaker with a 60 a breaker. https://www.lowes.com/pd/Eaton-Type-BR-60-Amp-2-Pole-Standard-Trip-Circuit-Breaker/1114115
To add to my posting, a shut off at sub panel at a detached building is required if number of breakers in that panel exceeds 6. Still best to wire a main breaker with less than 6 circuits in case you ever want to add more circuits.
I have 8 circuits in my sub panel so a shut off was required.
I have 8 circuits in my sub panel so a shut off was required.
