feeder wire for a subpanel

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I'm planning to install a subpanel on the 2nd floor that is fed from a main in the basement. I'm guessing it's about a 40' run. The panel will be 100A or 125A. The reading I've done so far suggested I need SER type cable for the feeder run. I couldn't find this cable at any local home store. One store had SER aluminum listed as special order, but they couldn't get it anyway.
Any idea what the right cable is for this? I also hope this comes as a sheathed cable, or would it be 4 separate cables?
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You can't run conduit? I'd use conduit and THHN conductors.
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Not unless I can get some kind of thin flexible conduit. I'll be running this across the basement (through the floor joists), up the inside of the wall, into an attic space, along a roof joist and down a wall stud into the new panel.
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If it's 4 seperate cables, they'll have to be in a conduit. What you need is 4/3 with ground. And it does come in romex if you go to the electrical supply house.
s

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They make romex in a large enough gauge for this? I was guessing it must be huge (e.g. 4 or 6 gauge)...
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On Dec 10, 10:42 pm, snipped-for-privacy@pookmail.com wrote:

I ran a feeder for an addition on my house, very similar to what you are talking about. It is SE cable or "Service Entrance" cable, and not exactly romex, but the same idea. I bought mine around the time copper was at the all time high, so we went with aluminum. It is 2-2-2-4 cable, with three 2 gauge conductors and one 4 gauge conductor for the ground. I think it was around $1.50 / foot, from a supply house. This was for 100 amps. I assume the copper equivalent would be one gauge smaller, but I don't have my code book in my hands.
My cable is about 1" in diameter, so the copper equivalent would be a little smaller, but still really substantial. You also want to be VERY sure that you don't run in where you might shoot a drywall screw or a nail into it. With 100A going through it, you could have a really bad day.
JK
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On Mon, 10 Dec 2007 20:42:49 -0800 (PST), snipped-for-privacy@pookmail.com wrote:

Romex tops out in #2 that would work for 100a if it was copper but he said aluminum.
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WHO said alum?
s

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I think I started the talk of aluminum, saying that I had used it for the cost savings over copper.
JK
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Yes, i was told (haven't actually bought it yet) by my supplier, that he has an NM-B 4/3 with ground.
s

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On Mon, 10 Dec 2007 18:27:54 -0800 (PST), snipped-for-privacy@pookmail.com wrote:

out of the "hobby" class that the home stores cater to. The other question is, are you sure you really need 100a? Are you using electric strip heat or a tankless water heater?
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So #1 SER is what I need?
I'm running a ton of stuff. I'll install 7 20A circuits. I calc the max simultaneous draw will be in the 70A range. It includes a couple space heaters, two electric griddles, a heat gun (the latter two for encaustic painting), computers, lighting, some tools. Part of what's going on is I'm making up for some homeowner installed way undersuitable wiring. My entire 2nd floor (about 500 sf) is tied into 1 first floor 20A circuit. So I can barely draw from the existing wiring for my needs.
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On Mon, 10 Dec 2007 20:51:16 -0800 (PST), snipped-for-privacy@pookmail.com wrote:

#1 aluminum or #2 copper for 100a
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On Dec 11, 12:18 am, snipped-for-privacy@aol.com wrote:

I'm not completely up on my code, but apparently there is an exception which allowed me to have 100A breaker with the 2-2-2-4 Aluminum SE cable. All the work was down under permit and has been inspected.
JK
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On Tue, 11 Dec 2007 07:14:11 -0800 (PST), Big_Jake

You are talking about 310.15(B)(6) but that only applies to the "main power feeder to a dwelling unit" not feeders to sub panels.
I doubt it would cause a problem in this application since I don't think he will draw anything near 100a but it is what the code says.
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ACTUALLY #4 can be run for the 100a sub panel.
s

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On Tue, 11 Dec 2007 10:58:22 -0600, "S. Barker"

cite that, it sure isn't what 310.15(B)(6) says
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On Dec 11, 11:29 am, snipped-for-privacy@aol.com wrote:

The Table in 310.15(B)(6) says, for a dwelling, which we are assuming this is, for a "Service or Feeder", which this sounds like, the rating in amps for a #4 copper or #2 aluminum shall be 100A. Are you saying that the problem is that it isn't a service but a subpanel? This should fall under the definition of "feeder" and I'm sure that my AHJ and electrician had that in mind when they allowed & ran my feeder, protected by a 100A breaker, through a piece of 2-2-2-4 Aluminum SE cable.
If I'm wrong, tell me how.
JK
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On Tue, 11 Dec 2007 17:48:25 -0800 (PST), Big_Jake

Read the text above the table. It says "feeder conductors that serve as the main power feeder to a dwelling unit". That means if this is the feeder to the main breaker you can use the table. This assumes the diversity of the total house load. You won't be using everything at once. That may not be true in a feeder to a sub panel since we don't know what the sub panel serves. Don't feel bad. A lot of people get confused by this, even inspectors who should know better.
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On Dec 11, 10:41 pm, snipped-for-privacy@aol.com wrote:

Here's a couple more for you - (I don't do this for a living)
According to another table in 310-16, my SE cable would have been ok for 100 amps if the wire was rated for 90c. and #4 Copper ok for 95 amps, which would can be "rounded up" to the next common breaker size, no?
JK
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