Sub panel question.

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Old 09-14-13, 08:41 AM
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Sub panel question.

I have a wire connecting my sub panel to my main 200 amp service. this is what it says:

Conal co-s type se cable style u type XHHW CDRS 300v to ground CDRS 4 AL 1 CDR 6 AL (UL)

It currently has a 50 amp breaker feeding it on a run of 30 ft. My question is what is the largest breaker that I can feed this sub panel with? Can I go with a 60 amp or even 100amp?

Other info:
Im putting in a new kitchen and Needed a few spaces for GFI's, and a microwave. The sub panel currently feeds my workshop and woodworking equipment. I dont think it would ever be above 70 amps per say unless I was using vacuum, saws and the wife had her mixer and a few other things running at the same time.

TIA!
 
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Old 09-14-13, 09:23 AM
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Do you have two or three insulated conductors in that cable? If you have only two, it will need to be replaced if it is in the same building as your service.
 
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Old 09-14-13, 09:47 AM
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it only has 2 insulated wires and one non insulated ground
 
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Old 09-14-13, 10:19 AM
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it only has 2 insulated wires and one non insulated ground
You need to use a cable with three insulated conductors and a grounding conductor - bare or insulated - or four insulated conductors in plastic or flexible conduit, or three insulated conductors in metal conduit rated and installed to provide a low-impedance path to ground. I always pull the fourth, grounding, conductor in that pipe anyway, just for belt-and-suspenders.

My question is what is the largest breaker that I can feed this sub panel with? Can I go with a 60 amp or even 100amp?
IDK. What is the rating of the subpanel? Is it a main breaker panel or a lug-connect panel?

The important consideration, though, is not what would it take to max out your existing subpanel. What's important is what the load on that panel will be.

Do a residential load calculation to determine the size of the conductors and the breaker. If you have Excel, you can use the calculator template available here: Mike Holt Free Resources Menu.
 

Last edited by Nashkat1; 09-15-13 at 07:31 AM.
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Old 09-15-13, 07:28 AM
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type se cable style u type XHHW CDRS 300v to ground
There is the key. Type SE Style U is service entrance cable with two insulated and one neutral conductor. 300V indicates this is older service entrance cable and could have been installed in the '60s, '70s or early '80s. As others have indicated, it needs to be replaced as there needs to be three insulated and one ground conductor. Type SE Style R has the proper conductors and is what is commonly used today. Newer service entrance cable is rated 600V to ground.
 
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