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50 amp sub panels from 100 amp main

11K views 10 replies 5 participants last post by  smithdavidp 
#1 ·
I worked as a electrical apprentice so I am no stranger to residential wiring. First off I just bought my house which has a G.E. main panel with a 100 amp main breaker. I am more of a square D fan and I am also wanting to run two 50 amp sub panels so I am wondering if I could use a 150amp Square D in place of the 100 amp GE. I have very little in the way of amp hungry appliances or tools. My refridgerator is the only electrical appliance along with a Microwave. The Mechanicals are the furnace and the central air. The central air is running off of a seperate sub panel and meter but come off of a cross connection to the main meter.

I want a 50 amp panel in the garage that will contain all of the garage circuits. These will power garage door opener, table saw, miter saw, drill press, air compressor (a 220 hookup but draws only 15 amps) and two 8 foot long florescent fixtures. I want to be able to shut off the power to the electrical tools when not in use for obvious safety reasons.

The second 50 amp panel will be located in the basement where I have a small recording studio. The circuits will carry only amplifiers, mixers, and lighting and will need to be run through a conditioned main circuit.

Can I do this without running into problems on the electric companies side of the equation? Will code allow me to have two 50 amp breakers inside the 150 amp main panel? Can I replace the 100amp with the 150 amp main breaker? I don't see where I would ever exceed the rated amperage that is in the house now. My concern is that second meter and the 30 amp breaker that come off of the main meter.

The electric company supplies this house with a cable attached between two poles (in the middle so to speak) and there is no connection to a 220 transformer.
 
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#3 ·
You can use any size panel you like as long as its fused for the service entrance conductors. Meaning you could install a 200 amp MLO or breaker panel inside with a 100 amp disconnect feeding it. Not a smart way to do it, but you can do it.
The house sounds fine on a 100 amp service. But your future additions may warrant a service upgrade.
 
#4 ·
I think what he wants to do is replace his 100amp main breaker panel with a 150amp panel. That is why I said it is probably a good idea to upgrade to 200amp for the future expansion since you can't just replace the main panel or breaker with a larger one. Unless maybe the service wires and meter socket are large enough to support it.
 
#5 ·
I think what he wants to do is replace his 100amp main breaker panel with a 150amp panel. That is why I said it is probably a good idea to upgrade to 200amp for the future expansion since you can't just replace the main panel or breaker with a larger one. Unless maybe the service wires and meter socket are large enough to support it.
The house was built in 1967. The service cable looks to be 100 amp judging by the size. The A/C cable (added after house was built) is 60 amp and not much smaller than the main service cable it self. By running the 50 amp cable to each of the two 50 amp panels I would be removing 2 circuits from the garage and 16 circuits from the basement out of the main panel. The previous owners built out part of the basement and have 9 recepticals running through a 20 amp breaker and 5 flourscent light fixtures, with ballast units, through another 20 amp breaker. Needless to say the house is not up to code now. I am guessing that there is going to have to be an upgrade now with a new service cable. Guess it will cost me more bucks. The original wiring is the old cloth coated wire. This house is starting to remind me of that "Money Trap" movie. Guess I have to call DTE and see what they are going to hit me with.
 
#6 ·
you can install whatever size panel you want. you just have to size your over current protection (breaker) to the wire you are using. sounds like you want to add more spaces to what is there now. if you are not adding any new loads, just spacing them out you should be okay. if you are adding any new loads, upgrade to 200 amp and take care of your potential problem with overloading your circuit and this will also prepare you for future expansion. if you don't know what your getting into, make sure your rod is grounded.
 
#11 ·
Box explaination

You may already know this but the two boxes above the A/C meter is an interupt circuit. DTE can interupt the A/C power when ever there is a chance of overload on the grid. They can shut the power off for the A/C, remotely, when ever they are reaching grid overload situations. Then all you can do is turn on the fans because you have no power to the A/C system.
 
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