charging subpanel

amakarevic

my house currently has a 150A main panel. since i am dividing the house into two units but cannot yet for various reasons get two separate meters, at least i want each unit to have independent access to their breakers so a subpanel is the answer.

Q1. if the main panel is 150, can the subpanel also be 150? i the subpanel effectively will need a maximum of really 80-100A, since both the dryer and stove and water heater are gas, i.e. not electric. so the biggest appliance would really be the washer. there are window AC units though, during the summer. the unit that will have the breakers in the main panel will be using more since the dryer, water heater, range, as well as the radiator hydronic heater will use electric. i do not know what the meter is but i guess it corresponds to the 150A of the main panel.

Q2. when charging the subpanel from the main panel, if the subpanel is 150A but i never expect that i will reach that kind of amperage at any given time, do i still use a 150A breaker in the main panel or something less? and which gauge wire do i use for 120, 240, neutral and ground (can the ground be smaller than the rest?)?

thanks

jbfan

The size of the subpanel is limited by the size of the branch circuit breaker allowed in the main panel.
Most I have seen only allow a 100 amp branch circuit from the main panel.

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amakarevic

can i use a 150 A panel for the subpanel but charge only 100A into it? because i don't wanna change it in the future when i do get a separate meter.

andrew79

Yes that's fine.

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amakarevic

what gauge wires should i use?

stickboy1375

IF you are transforming this into two rental units, you better make sure you can perform the work first...

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amakarevic

that is why i am asking the question

stickboy1375

Well, start with calling your local building department, not a DIY site... Your question should have read; " Can I wire a an apartment legally, or do I need I licensed contractor?"

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parman

Depending on your jurisdiction, there could be legal ramifications of you, as an unlicensed electrician, doing electrical work in a residence that will be used for rental space.

I highly recommend you contact your local authorities to find out what is required, as it pertains to electrical, in a rental unit.

You may be surprised of all the things your local authorities may require. It's better to do this now instead of finding out later when you try to rent and all of a sudden there are numerous requirements that you did not fathom.