Stranded wire sizes are confusing!

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Old 09-06-16, 08:16 PM
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Stranded wire sizes are confusing!

According to my utility company I'm needing to increase the wire size for the service entry wire in our cabin which, in turn, is going to require I install a new inside distribution box. I'm looking at an Eaton BR1224L125V1 who's brochure says the cable size is #6-2/0 AWG for the main supply lines (split phase), 2 wires total plus ground cable. If I'm reading this correctly it means the largest SE cable feed it will accept is a 6 gauge wire or could it mean a 2-aught (00) wire size with 6 gauge strands? The Wiki entry for Stranded AWG (https://en.wikipedia.org/wiki/American_wire_gauge) explains it one way, the brochure states it as I've copied and pasted above and the Eaton person that answered the question about largest SE wire this box's lugs would take stated "#6 to 2/0 wire". Suffice it to say I don't think the Eaton person knew exactly what they were talking about but it led me in the right direction for an answer. I'll take the brochure's description, though, but I still need to know what it means exactly.

I'm needing to have 100 amps coming into the house and the box is a 125 amp max distribution box. Also I'm assuming copper wire here.

Much thanks for clearing this up and I don't mind explaining anything else because I know I probably left something out.
 
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Old 09-06-16, 08:57 PM
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Welcome to the forums.

The panel's lugs accepts cable from #6 to 2/0. That's roughly 60A to 150A cable.
#6 is the smallest you can use and 2/0 is the largest you can use.

You would be using #3 copper or 1/0 aluminum for a 100A service.
The exact size of the wire depends if it will be in conduit or if service cable is used.
 
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Old 09-06-16, 09:22 PM
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I'm not following the description. What is the reason for all the changes? Is this a house or a cabin or both? Where is/will be the main disconnect? That Eaton is a main lug box so you may be better off getting a main breaker depending on what your setup is.
 
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Old 09-06-16, 10:05 PM
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If that, indeed, is the wire size range (#6 to 2/0) then that makes sense.

The wire would be going from a new 125 amp outside breaker box the utility guy and I installed last week. The old box had to be from the late 50s or early 60s. It had a 75 amp breaker on each leg of the 220v service but the hunters had installed a 100 amp breaker on each of the legs that feed the inside distribution box to keep from tripping them which, of course, meant the outside breakers haven't been working for a while.

This is one of those projects you run into where you have trouble figuring out where to stop. After I described the loads in the house to the utility guy - stove, one 220v water heater, one 120v water heater and at least four electric oil room heaters running when it's cold plus all the other electric amenities our hunters have moved in over the years - he took a look at the transformer and said we'd have to up it to at least a 5kw (currently it's a 3kw he said) or better, new wires from transformer to meter, probably replace the meter mount and maybe the pole. The SE wire going through the attic has been spliced at least 3 times on one leg. Twice on the other. One splice was so corroded I had to wire brush the under-sized wire and replace the clamp. I found this out one morning when I discovered I'd lost one whole leg of the 220 while renovating one of the bathrooms and half the plugs in the house were dead. For all these reasons and more I'm going to go with new, properly sized wire and probably a new distribution box inside to handle the increased load that's been put on the system. And this is just for the electrical system this year! I still have to get one bathroom renovated this year and renovate and get hot water into the kitchen next year.

Bewaaaare of Pintrest! Be very aware before it sets you on one of these paths!

There's more but let's just say I'm surprised the place hasn't burned down yet. The former owner didn't care a whole lot about doing things right as long as his constructions worked when he was done. This means this generation, meaning me, has a lot of catching up to do if I don't want to build a whole new house, cabin or whatever you call it out there.
 
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Old 09-07-16, 06:08 PM
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I'm needing to have 100 amps coming into the house and the box is a 125 amp max distribution box. Also I'm assuming copper wire here.
You need 100 amps yet you already installed a 125 amp breaker disconnect outside at the meter? I think now you should forget about 100 amps and install 125 amp service entrance wiring. What kind of cable did you install from the weatherhead to a new 125 amp meter socket?

FYI: The NEC allows either #4 copper or #2 aluminum for a 100 amp service. The NEC also allows either #2 copper or #1/0 aluminum for a 125 amp service.

Considering that you already have the new 125 amp disconnect, I'd install #2 copper SEU cable to the new main lug panel inside.
 
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Old 09-07-16, 07:31 PM
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The correct way to size the service would have been by doing a demand load calculation.
 
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Old 09-07-16, 09:24 PM
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2/0 copper for each leg of the SE wire is what I was figuring on running from the new outside breakers to the inside distribution panel along with the bare neutral ground wire. I called the utility company today asking when they intend to come out but they've not set any schedule for it as yet. The outside breaker box's SE wires go back up the meter pole to a weatherhead which is mixed in with all the other supply wires so I don't intend to get in amongst that until the utility company can disconnect the transformer and kill all power. From that pole, then, they are suspended by the bare neutral wire to another weatherhead under the eve of the house. As yet I don't know if these two weatherheads will allow SE wires of this size to pass so I have some homework to do along with everything else. I'm sure this is going to be a lot like plumbing in that a lot more is going to get broken and fixed before I can call this job done.

Right now I'm the only one out there using any current other than the refrigerator so demand is low but I need to get this corrected before the guys descend on the place and start flipping switches and plugging all their gear in.

The electrical boxes available at Lowe's and Home Depot were 100, 125 and then 150 amp available, I believe, so I figured some excess capability was called for over what had been installed to keep the breakers from tripping. I know, it's all seat-of-the-pants figuring but I'm bouncing as much as I can off the utility company's people as I go as well as here. By a demand load calculation I guess you mean to add up all the major and as many of the minor loads there are in the house at peak demand to size the wire properly. I hope it doesn't mean to have everything turned on and put a amp meter around the SE wire because I really don't want that much current being drawn on these old wires now that I know the state they're in.

Thanks.
 
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Old 09-08-16, 12:43 PM
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From the descriptions given it looks like you would save time and money by hiring a competent electrician who could size things appropriately.
 
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Old 09-10-16, 01:11 PM
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I'd install #2 copper SEU cable to the new main lug panel inside.
I just caught my typo, that should have read SER cable because this is feeding a subpanel which requires 4 wires.


2/0 copper for each leg of the SE wire is what I was figuring on running from the new outside breakers to the inside distribution panel along with the bare neutral ground wire.
2/0 copper is good for 200 amps and may not fit the lugs of the disconnect breaker. The cable will be SER cable with 3 insulated conductors (2 hots and 1 neutral) and 1 bare ground. SER cable doesn't use a bare neutral.

From the descriptions given it looks like you would save time and money by hiring a competent electrician who could size things appropriately.
Excellent suggestion.
 
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