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Jerryham · Mar 7, 2013, 01:33 PM

This is my first shot at asking a question.
Getting ready to bid on finishing a bedroom in a basement. I have several questions. This house has a 100a service. My first question is:
1. Is there a way to tell if the current 100a service has enough amperage left to cover the two circuits that will be added.

2. Currently they have two refrigerators, a/c 30a, electric stove 40, electric dryer 30a, microwave, and four 20a breakers for lights and outlets. One of the 20a breakers is for the part of the basement that is already finished. It has a 1500w space heater on one of the outlets. Another outlet has a set of electric logs that are plugged in to an outlet. The logs aren't running now. The manuf tag says 120v 12.5a on it. My concern is that it is already loaded even thought there are about 8 cover plates open for installing more breakers. The circuits that will be added are the following: one circuit with light and outlet for plugging in blowdryer (probably 1500w). The other will be six outlets, one fan with light kit. Will they need to move up to a 200a service? Price is an issue, so they won't want to spend the money to move up unless it is necessary.

3. Moving forward is there a way to calculate as to whether you have reached capacity on an existing panel?
Thanks

Jerryham2

stanfortyman · Mar 7, 2013, 02:43 PM

Why not let the electrician doing the job worry about this?

Jerryham · Mar 7, 2013, 03:53 PM

Because I don't have an electrician at this point. I'm trying to put together some budgetary numbers together before they even move forward with the project. If I can give them a heads up that they may be looking at a panel, then I I'm helping the customer. Along the same lines, I would like to gain mo knowledge concerning this issue. If it's something only an electrician can determine then that's OK. Just would like to know.

donf · Mar 9, 2013, 05:56 AM

The NEC provide a section of code for doing a "Load Calculation" It is a fairly complicated process if you have never done one before.

Under current code, 100 Amp is the minimum service for a stand alone residence.

From what you describe I do not believe you will overload the panel. However, a Load Calculation will tell you. By the way, you do not add the amperage of the breakers to arrive at the current load.