Extending a Breaker Panel.

[Andy]

Andy writes;

If your existing breaker panel has a second set of lugs on the main input for going to a second panel, I would use these. Be sure to use the same wire size that goes from the meter to the main panel to go from the main to the second panel. It isn't far, and won't cost much. Probably something like 2/0 , if memory serves, and carry the neutral and ground and both sides of the line. Do not use a new ground rod for the second panel, but put a BIG neutral, like #6 or bigger, between the two panels.

Use both phases of the input and try to put about half of the breakers in the new panel on one line and the other half on the other. They will all work on one phase, but dividing them is a better way to do it.....

Andy

[PVR]

My breaker panel is a Square D, Homeline, 30/30 type with a 200 amp supply. All breaker spaces are in use. Being a 30/30 type I cannot replace some of the existing breakers with two gang, 120 volt breakers. Is this correct?

I'm assuming I need to extend my existing breaker panel with a second small panel. Should this be wired to the main feed or can it be wired to the buses inside the existing panel? The second would be easier for me. There will be five extra circuits, some twenty amp, some 15 amp. Do these five extra circuits need to be divided among two phases or can I put them all on one phase? An additional panel would be small and would have to be placed below the existing panel. Is this a problem for inspection?

I appreciate all the help I can get.

Peter.

[gfretwell]

Nope, you would then be overloading the service entrance. Without upgrading the service you will have to go from the bus in the panel downstream of the service disconnect.

Your panel may be able to accept a bus tap (be sure you understand the "tap" rules) but you may end up having to move 2 circuits to the sub and installing a 2 pole breaker to feed a MLO sub panel.

[SQLit]

the breakers your thinking of are called "twins" 2 breakers on one pole space.

Best start with your utility company and find out if your even using close to the 200 amps. (probably not) That means you could do some rearranging and put in a sub panel for some added pole spaces. Call a local licensed and bonded pro and have them come out and look at the job. We are all just guessing with little information.

[Olaf]

If you wire off of the main feeders from the meter your subpanel should have a main shutoff. I'd wire the subpanel from a 2 pole breaker in the main panel. Remove 2 existing circuits from the main panel and put them in the subpanel. Your subpanel doesn't necessarily need to be small. I have a 30 space panel nearly filled (3 left) and I have 100 amp service. Subpanels are surprisingly inexpensive. Get one with as many spaces as you can afford that'll fit where you want it.

You'll need to buy an appropriately sized breaker for your main panel as well as the proper size wire. Make sure the neutral isn't bonded to the case in the subpanel and run a separate ground and (insulated) neutral from the main panel.

[PVR]

Many thanks to all who replied. You have given me some great ideas which are much appreciated.

Peter.

[Andy]

Andy replies:

I agree with you.... I was assuming that the main disconnect would also disable the second set of lugs. I have seen panels where this is standard.... Perhaps I should have been clearer..... Thanks for pointing this out, tho I cannot conceive of any manufacturer who would not have a disconnect prior to a second take-off...... It would be a big liability issue if anyone decided to use them.....

Andy

[PVR]

Many thanks to all. I put in a small sub panel via a nipple. Feed was from a

60 amp double breaker on the main panel. The sub panel has six spaces which also accept twin breakers. I have installed four single breakers and two twin breakers for a total of eight circuits. Everything works OK.

Peter.