Seeking Advice - New Main Breaker & Sub-Panel

[BiloxiBoy]

Since Hurricane Katrina gutted my home - and took all the sheetrock with it - I am upgrading ALL of the wiring (used to be "mostly" ungrounded throughout). Consequently, I want to add a new sub-panel inside the home to which all circuits will run. This will eliminate the present setup of an ungrounded 4-circuit box and another grounded (but very old) fuse panel. The home is small - only about 1,000 sq. feet. To power that sub-panel, here's the way I've got it sketched out:

Outside and adjacent to the meter, I will add a single 100A main circuit breaker in a dedicated box. That breaker will then supply power to the sub-panel (about 30 feet away) via a #4, four-wire romex cable with two hots, a neutral, and a ground. I will bond the ground and neutral at the main circuit breaker outside and separate them at the sub. The sub contains 12 breakers and has no main breaker. To ground the system, I will run #6 copper wire from the 100A breaker box outside to an 8-foot grounding rod just below the box.

Currently, another panel is also connected to the meter and it provides power to the A/C, a detached shop, and the two old panels listed above. My plan is to leave it in place as is (minus the two 60A breakers for the old panels) and wire the new 100A breaker box to the meter as well.

Can I wire both boxes to the load side of the meter, or is there a better or another way?

Any input on my plan or the question would be appreciated.

[Bob]

Put in a whole new main panel and run all new wiring back to it.

[BiloxiBoy]

Thanks, Bob. That sounds like a great idea but I'm wondering if I can buy a panel that has only a few spaces, and I guess I'd also have these questions:

1. Since the entire house load calculates out to about 81 amps (excluding central A/C), should I get a 100A main service panel, or should I go higher? All the big appliances are gas - stove, dryer, and central heat.
2. If I go higher, how high can I go before the service has to be upgraded at the meter?
3. If I get a 100A panel, can I still run a sub panel to the shop (no

220) and still supply power to the central air?

1. What size main breaker would I need for the house panel, and does it run off it's own breaker or will the main switch in the new main panel suffice?

Sorry for all the questions, but it seems these are the kinds of things that a lot of folks know a whole lot more about that I do...

[Tom Horne, Electrician]

That existing outdoor panel is your service equipment. You will need to answer some questions first before we can provide valid answers. How many breakers is the existing outdoor panel, that is supplied directly from the meter, capable of holding? What is the listed ampacity of the existing outdoor panel? Is your service overhead or underground? What size in amperes is the meter can? What wire gage are the Service entry conductors that supply your meter from the end of your service drop of lateral? Do you have the room to install a wiring trough between the meter can and the existing service equipment? Do you have any way to post photographs of the existing panels and meter.

I really do want to help. You folks have been through enough without having problems with misinformation during reconstruction. I would welcome direct Email or telephone contact. If you Email your telephone number I will call you to save you the cost of the call or if you would prefer you can ask for my number and I will give it to you.

[BiloxiBoy]

Wow Tom - Thanks for the reply, and for the compasion in your post. It has, to say the least, been an interesting four months since Katrina!! We have a loooong way to go, but every day with progress is a step in the right direction...

In answer, here's what I have now:

The outdoor panel has four breakers; a 60A and a 30A to the two existing sub-panels inside, a 40A for the A/C, and a 20A(??) for the shop. There is no more room for any more breakers - at least not double-pole.

I'm not sure on the ampacity on the existing panel outside as it is very old and has no doubt seen its better days. No lables that I can find!! The house was built in the 40's, and might have received a minimal service upgrade in the 60's, but that's about it.

The service is overhead and there's a brand new meter can that I installed in the days shortly after the storm while the power was still off everywhere (the old one was ripped off the side of the house, and I "straigntened" the mast out for re-use).

I'm not sure what the meter can is rated at, but here's a picture of the meter, the existing service, and the new panel I have just wired inside (not hot yet):

Not sure on the guage of the wire from the meter to the existing panel, but it is brand new since Katrina as I got it from the neighbor who had it as leftovers since he had recently upgraded to 200A service. It is bigger than what I took out - that I do know.

As for the trough, there is presently a steel conduit that connects the two - and the present panel box is directly below the meter, but not an integral part. There are two other unused knockouts on the bottom of the meter can, and one on each side.

Again, I sincerely appreciate your input and your offer for assistance. It's nice to know there are folks out there who recognize how things are going around here.

[BiloxiBoy]

Thanks, Tom for the reply and for the compasion in your post. In answer, here's what I have now:

There are four breakers in the outdoor panel - a 60A and a 30A for the two existing sub-panels inside, a 40A for the A/C, and a 20A (??) for the shop. There is no more room for any others - at least not double-pole.

Not sure on the ampacity of the existing service panel as it is very old and has seen its better days. No lables that I can find. It is shown (inside cover still on) in the picture link below.

The service is overhead and the meter can is new since Katrina as the old one was ripped off the side of the house. I bought and installed it in the days following the storm, but I am not sure of the rating - but is is brand new. Here's a link to the picture.

The wires from the meter to the panel are new since Katrina as well. I got the cable from a neighbor who had just recently upgraded his service to 200A. Not sure on the size, but it is bigger than what I took out.

As for a trough, there is presently a metal conduit connecting the meter to the panel. There are also two other unused knockouts on the bottom of the can and one on each side.

Again, thanks for your help and your recognition of the conditions here. We've got a looooong way to go, but progress every day is contributing to success in the long term.

[Thomas D. Horne, FF EMT]

George

What I would suggest is a new panel to replace your old outdoor one. That will cost the same or less than a separate disconnect or breaker enclosure. Your new Service Equipment should have a main breaker and room for 12 or so load breakers. The Square D QO version of that panel can be equipped with a manual interlock to permit generator supply to your home. That panel will have a 200 ampere main breaker and plenty of room for the breakers to supply your existing loads. You cannot attach additional equipment to your existing meter's lugs unless they were specifically designed for that service. A replacement panel will also provide a neat and well organized layout.

[Thomas D. Horne, FF EMT]

I would suggest a larger service equipment panel. The difference in price between 150 and 200 amp equipment is rather small so I'd go for

200 amps unless the existing service entry conductors will carry 150 but are too small for 200. If the existing service entry conductors will not carry 150 I suggest you make the jump to 200 as the difference in cost is small. Having enough ampacity in the service for future expansion of electrical use is a good thing. A hot tub, for instance, would draw nearly 40 amperes.

[BiloxiBoy]

Thanks, Tom... Your advice is certainly appreciated. The single-breaker panel is going back to the store and will be replaced with the new 200A QO model.

Many thanks again... All we gotta do now is hope another storm doesn't grace our shores next season!! At least by then, I hope to be fully repaired at every level - and this time with a new generator interlock ready to go.