Subpanel wiring options


Old 03-14-11, 09:40 PM
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Subpanel wiring options

I am doing a couple upgrades in an old home which was built in the 50s.

House has lots of K&T, with some upgraded 2 wire romex sprinkled in.

I was considering adding a small breaker subpanel to add a circuit for a dishwasher.

The house currently has fuse boxes. The main box has a 60 main fuse, with 6 20 amp circuits. Spliced off the bottom of the main fuse, there is a feed to a 60 amp fuse disconnect that supplies the range. There is also a feed that runs to a separate fuse box with 6 more 20 amp circuits. There are no more empty spaces in either fuse box.

Upgrading the service is out of the question.

Would it be ok to add in another feeder off the bottom of the main 60 amp fuse set to supply a subpanel? Or feed from the range fuse disconnect?

Since there seems to be a lack of a ground anywhere, I was going to use a GFCI breaker on the dishwasher.

Any other options for the dishwasher?

Thanks in advance
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Old 03-15-11, 07:22 AM
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It would be wise to do a demand load calculation to see how heavily your existing service is loaded and see if there is capacity to add more load.

The new wiring for the dishwasher would have a ground. You do not want to tap off the range circuit.

I think the arrangement you have now may have outlived its useful life.
Old 03-15-11, 02:57 PM
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I'm looking into the load calcs. There isnt much in this house. 1 floor of lights and outlets, a range, furnace blower, fridge. Hot water is gas, no A/C. Its pretty basic.
Old 03-15-11, 04:06 PM
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The problem is, you have no other ways to feed another box, if I read right. Those boxes usually had a set up to feed another box, which yours is doing, and maybe the other box has one you could use. But otherwise you might have to do like I did many years ago and maybe add an outside panel near your incoming service entrance. if you have 100 amp cable you could add either a 100 amp breaker panel with a 60 amp to feed your old stuff and then build off it. Just a suggestion. Otherwise, check the second box for a sub feed lug set up. One big problem is that you can't buy the inner shells for those boxes and pullouts are almost impossible to find even used. A 100 amp upgrade would be the way to go. But since that is impossible right now take a look at the outside panel. While not the best way to do this I suppose you could buy a 4 circuit panel, remove the wire from the first panel and feed this new panel. Then, add a 60 amp breaker or smaller and feed the second one from that, along with your breaker for your new dishwasher. That is mechanically possible but not the best.
Old 03-15-11, 06:24 PM
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The main box has a 60 main fuse
You need a new service in the worst way. Your 60 amp service is now at maximum load.
Old 03-16-11, 10:06 AM
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I see no way to expand the original service within code. You can't extend any of the original circuits because they are ungrounded. You can't add any new circuits because the panels are full. You can't convert the range to a subpanel because it has an obsolete three wire feeder. You can't feed the range from a subpanel because it has a three wire circuit. You can't alter any of the existing circuits because you cannot provide AFCI protection with a fuse panel.

The service is grandfathered as-is, but at 60 years old any alterations would not meet code today.

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