View Full Version : Adding second breaker box

08-21-2007, 05:52 PM
I know that if I do everything I 'WANT' to do for lights this year, I will be replacing 100 amp main fuses all the time.


I have added a sidecar Square D pannel because I needed more circuits and I wired this to my existing pannel.

What I want to do is add another 100 amp breaker pannel and wire it to the meter directly instead of replacing my existing pannel with a 200 amp one. The cost of doing that is more than I am willing to do because I am sure none of the existing circuits will reach their new breakers in a new pannel and it will be lots of small patch wires inside the pannel. An ugly mess.

Does anyone know if it is 'CODE' to put in another pannel? Or can I put in a 200 amp main breaker and wire both pannels to that new main? Who would know these answers? I am not interested in hiring an electrican.

I know this is not for everyone, but I have no problem working with high voltage, I have done it for years trained by pros.

- Michael

Dan Ross
08-21-2007, 06:07 PM
I am no pro at this stuff but my first two thoughts are (first thought) Look up the specs to the box you have and see if it is rated for 200 amps. If it is then I would (2nd thought) call the power company and make sure your meter is rated for 200 amps.

I am currently have a house built and one of the questions the power company asked is what service (how many amps the main breaker is rated for) is my panel going to be.

As for adding a box next to your current one I would imagine you would need a permit for it. If you don't care and want to install it anyway still refer to my second thought. The power company should be able to tell you wether or not you need a permit.

Wayne J
08-21-2007, 06:11 PM
I too have the same trouble. My soulution (for this year) is a temporary box (50A) outside off the main panel outside, this will feed 8 gfic outlets in another box I built to the front of the house. After display season is over. I will recycle the parts to make a permanent panel after the garage is built. Extra work, I know, but my only option right now, as I don't want to do anything in the house since I have a garage going up next year.

08-21-2007, 08:20 PM
At my last house I added a studio to the deck and added a second 100 amp box to run power that outbuilding. Depending on your local code you will probably need to have the box looked at by the inspector before use.

I would go to the local building inspector's office (or call) and find out what you need to know. Whether you get it installed professionally or do it yourself ,... the inspector still has to put his stamp on it.

08-21-2007, 09:49 PM
Has anyone here, actually poped a 100 Amp main because of Christmas lights?

08-21-2007, 10:10 PM
I am not sure about your local codes but as far as I am aware the NEC requires 1 "main disconnect" for each residence. So to put a second "main disconnect" by adding a panel from the meter would seem like a violation to me but I am not 100% sure. Please consult a licensed electrician in your area.

08-22-2007, 10:23 AM
I think Brian is correct. If you are going to put in another panel with a main disconnect you have to have the power company add an additional meter to the house.

I went a little easier route. Are houses here are wired for Electic Dryers and Electric Ranges as well as plumbed for Gas. I use Gas Ranges and Gas Dryers so that leaves two 220volt circuits (one is 80 amps and the other is 60 amps) for use for Christmas lights. I splice the wire and run them to some Square D sub panels.

Seems to work and doesn't violate any codes that I am aware of.

Jeff Millard
08-23-2007, 11:28 PM
Has anyone here, actually poped a 100 Amp main because of Christmas lights?

This year, if my main was 100... it would pop.

I want to ring in on a couple things here. First, adding a second panel doesn't always require a second meter. That's usually a homeowner choice if the home is being subleted. A way to split the charges.

However, the discussion about the capacity of the meter is an important issue. Not only is the meter an issue, but the service drop is usually matched to the service capacity. There is a safety margin, but you wouldn't want to double the load without having the drop replaced.

Further, there is the capacity of the transformer to consider. Tripping the safety breaker on the transformer with 100 amps of lights that push it to overload, isn't a very good way to nurture neighbor relations.

The key here is what you are allowed to do by code and local government regulations. It would be a good idea to go to the permitting office and ask a few questions about who is allowed to make the modifications. Here, it's only the homeowner and a Licensed Electrician. Some places the owner isn't even allowed. Then cover all the bases. If you don't want to hire a Licensed Electrician, at least consult with one. Make sure the mods you are doing won't damage your home. Think of the liability issues. This isn't like wiring an outlet. When I upgraded to my 200amp service last year it took me almost three months. I had to get the permit, have the overhead construction engineering dept. do a survey of the transformer load, do some work, hook up a temp to power it up, get it inspected, fix the things that I did wrong, move the load, get it final inspected, after waiting a week I had to call and then hand carry the cut-card to get the utility to install the new meter and drop... It's not as easy as just adding a new panel.

It's very rewarding to do one of these upgrades yourself. Not only do you save a heck of a lot of money, but you did it yourself. But to do that, you have to involve the township and the utility. They are there to help you and will usually give you the information you need to do it safely.


08-24-2007, 11:29 AM
Thank you everyone for all of the good advise.
I did not think about the transformer load, but I know the service lines to the house were upgraded 2 years ago. We came home to find part of the wire hanging in the yard sparking and I asked the repair man at that time if the new one he was putting in would handle 200 amps and he said yes.
I have contacted our power company and they are trying to find the right person to call me back for details on how to go about this. My guess is that it will not happen this year if I have to go through all of the permitting process.
My current power estimates put me at about 80 amps with everything on (just christmast lights) so I have already informed the family there will be no dryer, oven, vaccume or anything on while the display is running. I just hope the fridge and freezer do not kick on at the same time.
Since I know I am right on the safety line, I have order a Kill-O-Watt meter to make sure I stay under limits.
I wish the price of LED's would drop !

- Michael

08-24-2007, 12:14 PM
One thing to remember here is that your 80 amps of Christmas lights is a single phase load. That means 80 amps at 120 volts. You have 240 volts coming in to your house. A 100 amp 240 volt service has 100 amps on each leg. Thus effectively you could divide your load and be able to achieve a 100 amp load per leg or 200 amps total at 110 volts. What I suggest you do, and I recommend this to everyone here is to figure out your load based on circuits and then make sure you divide those circuits evenly on each leg or phase of your service. This way you an even load distribution in your panel. This will make it less likely that you will blow your main by using the microwave or ....... If you follow that you will only load up about 40 amps per phase and then you could turn on every element on your electric range and still have electric to spare.

Load balancing is required in every service for things to work properly.


08-24-2007, 03:54 PM
Now that I was not aware of. I thought you could only have 100 amps total, not per leg. If that is so, then I will not have any problems, because I have already balanced everything out with 8 new 20 amp circuits on a sidecar pannel dedicated for outside lights. Thank you for that information. Let the lights shine!

- Michael

08-25-2007, 03:41 PM
Im an idiot

08-25-2007, 04:58 PM
My math doesn't come out quite the same. I am missing something.

.3 amps @ 120 volt per string of 100 lights by my measurements.

if I had 100 amps to play with 100 / .3 = 333.33 string of lights of 100 lights = 33,333 lights. not millions. But I could be wrong.

if you used both 100 amp legs you would handle 666 string but we need to stay at 80% so 666 * .8 = ~ 532 strings of lights with no microwave / tv or dryer.

532 * .3 amps = 159.6 amps and 19,152 watts of lights.
80% of 200 amps = 160 amps

but please don't try it. I like you guys to much to have your houses burning down.

08-25-2007, 05:15 PM
Yea my calculations are wrong.Ill fix it
Too many head injurys and too much fun in the 70s i guess.

Jeff Millard
08-25-2007, 05:19 PM
Whoops, I almost messed up big time. I was going to quote RJ and clicked the edit button instead. When I quote, I usually delete everything that's not on topic with my reply... That would have been the meat of his post... :oops: I completely forget the Mods right to edit posts. Man, I'd be wipin' egg off my face fer weeks...

BTW, I was going to agree with RJ's math. When I tried it, my numbers were the same as his. I couldn't figure out how to reproduce the other numbers...

08-25-2007, 05:46 PM
You divide apples by oranges . I didn't convert the amps into watts.

08-25-2007, 05:58 PM
Oh great " :oops: Honey could you put 100,000 strings back in the basement" RJ says we cant power them off two outlets

09-09-2007, 07:20 PM
Ive been reading all over this site and havent found any poststhat positively say that a homeowner can add a "temp" panel, and how to do it legally. Ive been reading up on codes for installing my system. (The city I live in says that they follow all the rules and codes found in the NEC book for the 2002 edition) I want to run 220 to a seperate temp box and use that box to power my display. My plan was to install another 220 breaker in my main breakerpanel and then run the 220 to my temp box. I went to Lowes today and asked if I could do this and the guy told me "no". He said that I cannot add a breaker to my box under NEC code, since Im not a liscensed electrician. Is this true? If that is true, heres another question. Since I have a 220 breaker not being used already in the breakerpanel(the house had a window ac unit that this was feeding) Can I 'move' the existing romex and wire it into my temp box?

Ive read all the codes about having temp installments for 90 days for holidays, but those dont mention a whole lot. Does anyone know where in the NEC guide (online guide) it mentions who can install a circuit?

09-09-2007, 09:02 PM
There are lots of really good books that detail how to install new breakers or to expand your service if you have room in your box.
But if you have a 220 circuit that is not being used, I dont see why you can't extend that to wherever you need it. I guess what I'm saying is that I'm not a licensed electrician but I am a homeowner who has built a studio under North Carolina building codes. I brought power from my service box (after the meter) to the studio and got it checked off by the inspecter after I finished. Moving an unused 220 circuit to another area of your house should be OK. But always check with your local building code authority to be sure.

09-09-2007, 11:07 PM
This is from the Mobile County Inspection Office web site:

Residential Building Permits:
If Everything is in Order,
The County Inspection Office Will Issue You:

A building permit for new construction or renovation of your home, or

An electrical permit, allowing an electrician licensed in Mobile County or owner to hook up the power from the utility service point to premises wiring system.

If you are building a new home and have hired a licensed contractor to perform the work. The contractor is required to get the permit.

It's my understanding that here, in my county, the only work that "Requires" a licensed contractor is AC/Mechanical.. everything else can be done by the homeowner. If the homeowner is getting the permit then it is assumed the homeowner is doing the work.
I'm sure this varies by location, and just because it's allowed doesn't mean you should, let common sense and prudence prevail.


09-12-2007, 08:48 PM
up grade the main to 200 amps then get a spider box 240volt (temporary power distribution box) u see them at construction sites and events. you can buy more than one and hook them together, and be able to place them in the yard where u need. mine powers more than 3/4 of my lights have 20,000. mine has 6 110 outlets and 1 220 outlet. other configurations are availabe. there about $200, the real money will come from the bologna wire you need. www.cepnow.com

09-17-2007, 10:28 PM
Here is what it comes down to. I am a Firefighter that builds homes for a living on my off days. I am not an electrician, but I do deal with city inspections and codes. First off I would check to see what your main panel is rated for. If it is rated for 200amps, don’t put a larger main in that panel. The electric company engineers the drop off what they calculate that homes load to be. I am sure there is room for some upgrade, but you can't put an additional 200amp panel for a total of 400 without dealing with your main panel and meter first. With that said, every area is different in what they require to be permitted. In our area a home owner can pull all their own permits and do all their own work. It has to pass code and you are not supposed to hire outside contractors without notifying the city and having them pull their own permits. I would imagine that most cities if you asked them say you need a permit. I have a 200amp panel. I have a 100amp pool sub panel off of that. The theory is that you are not using all of that power at one time. If you are worried about overloading you could turn certain circuits off while you are running your display so that wont happen. Either way, if you are learning from a book I would have somebody check your work before you turn things on. It could be your house that burns or someone injured if you don't. Just because the circuit doesn't trip doesn't mean it is wired right. I don't know if any of this helped. Jerome

11-04-2007, 04:31 PM
My main breaker never popped, but it did MELT, i'm guessing it was defective, replaced it and it popped so i had to turn off most things in the house (why would I decrease my lights?)

11-04-2007, 11:19 PM
Good God.... what are you running that draws over 100 amps!?