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-   -   Main Service Disconnects (http://www.diychatroom.com/f18/main-service-disconnects-31142/)

rwlawrence 11-03-2008 01:17 PM

Main Service Disconnects
 
I have a main and subpanel in my house. The power runs to the main and is connected to 2 main service disconnects, one disconnects the subpanel and one disconnects the main panel.
My question is this: Below the main panel disconnect (100 amp) was another 30 amp 240 v double pole breaker that controlled ceiling heat in my house. The ceiling heat was replaced with a fan heater and the breaker does not need to be 30 amp but instead 20 amp now. If the 30 amp breaker was marked "main service disconnect", does this mean that I need a special breaker for the new 20 amp heater or can I go with a regular 240 v double pole breaker? It appears that this was done on the other side of the panel with a 20 amp double pole. I guess my actual question is why are there more than 2 main service disconnects and are they necessary?
Thanks in advance, hopefully this makes sense.

Randy

J. V. 11-03-2008 02:47 PM

Quote:

Originally Posted by rwlawrence (Post 180224)
I have a main and subpanel in my house. The power runs to the main and is connected to 2 main service disconnects, one disconnects the subpanel and one disconnects the main panel.
My question is this: Below the main panel disconnect (100 amp) was another 30 amp 240 v double pole breaker that controlled ceiling heat in my house. The ceiling heat was replaced with a fan heater and the breaker does not need to be 30 amp but instead 20 amp now. If the 30 amp breaker was marked "main service disconnect", does this mean that I need a special breaker for the new 20 amp heater or can I go with a regular 240 v double pole breaker? It appears that this was done on the other side of the panel with a 20 amp double pole. I guess my actual question is why are there more than 2 main service disconnects and are they necessary?
Thanks in advance, hopefully this makes sense.

Randy

You can use a standard 20 amp single pole breaker in the main or in the 3rd sub panel below the 100 amp disco. How is this 30 amp main fed. Does it come off one of the breakers in the main. If it is not fed from a breaker, how is it fed from the disco or the panel.

One disconnect is for the main panel and the other is for the sub panel. Both panels could have been protected by a main breaker in each panel. Two disconnects are over kill, as they must be fed from a breaker anyway.
That 30 amp breaker under your main disco is a 3rd sub panel and also must be fed from a breaker.

I hope I made sense too.

rwlawrence 11-03-2008 03:36 PM

I did some more looking at the setup and it looks like the 30 amp does not actually disconnect the breakers below it (the 100 amp does though). However when I connected the 20 amp, it still was hot even when the main panel disconnect was off. I think that you are right, this is for another subpanel if you want one, however it was wired for a heating circuit instead.

Basically it looks like the main wiring into the house feeds 2 bars that break after the 3 first breakers (2 100 amp and 1 30 amp). The 30 amp spans the 2 bars and this I think is why it still ran when the 100 amp one was off. If I just hook below the break in the bars, is that okay?

Cheers

SD515 11-03-2008 04:30 PM

I wonder if this is a split-busbar PushOMatic.

rwlawrence 11-03-2008 05:01 PM

It is a square D panel. A bit older though.

J. V. 11-04-2008 11:46 AM

Why don't you take a few pictures for us. I personally am having a hard time picturing your setup.


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