Breaker Box, load center, fuse panel or whatever you call it

[rlgarber]

I just recently bought an older house and i am planning on doing some expanding and remodeling in the future. I got looking around most of my plugs are 2 prong, I only have two open slots left in a sixteen slot breaker box, and I have 2 sub panels with twist fuses. My main question is how do I determine for sure if I have a 100 or 200 amp service ( I believe I have a 100 ) and a secondary question, if I have a 100 amp service what is involved in converting it to a 200 amp, is it more than just changing the box and rewiring the plugs to three prong ( I am rewiring for three prong already ). I know how to wire outlets and such but have not had much dealings with the breaker box. Hope I don't sound too studip with this question, but these questions have been bothering me.

Any help is greatly appreciated.

[imported_trinitro]

The main breaker will tell you the size of the service. Upgrading to a 200A will involve replacing the main panel, probably the meter box and the wiring in between the panel to the meter box to the weather head. They'll all need to be at least 200A.
Regarding your panel problem, you could always replace one of your fused subpanels with a breaker subpanel with more spaces. But you should do a load calculation to make sure you're not overtaxing your service line. I've seen a 60A service panel with 3 subpanels and the owner was complaining the main breaker kept on tripping (accorinding to him everything should have been ok since he followed to code to the letter (except the service line)).

[Wgoodrich]

Links to supplement the previous reply try the following links;

Format so you can calculate your own demand load calculation to find what minimum service size you need for your home to meet minimum safety standards. Then once you know what minimum amp service size is required then you can make an informed decision as to how much more than minimum service size you want to install.

http://www.homewiringandmore.com/homewiringusa/2002/definitions/demandcalc02/DwlingDmdCalc02.html

Self help chapter on wiring a new or replacement main service, meter and riser for Utility company to connect to. Remember to get any required electrical permits before you start your project.

http://www.homewiringandmore.com/homewiringusa/2002/maindwelling/meter/meter.html

If you are replacing two prong receptacle with three prong receptacles then you have four choices to do this;

Install GFI protection due to lacking an equipment grounding conductor before you replace that two prong receptacle with a three prong receptacle.

or

Install a green insulated equipment grounding conductor as close to the original wires as you can and run it all the way from the grounding bar inside the main service rated panel to that replaced receptacle before you replace that two wire receptacle to a three prong receptacle.

or

Install a new Romex cable 12/2wGrnd to replace that two wire branch circuit before you change to three prong receptacles.

or

Install a new replacement two prong receptacle to replace that two prong receptacle.

The above are interpretations of the NEC rules that apply to your project.

Hope this helps

Wg

[rlgarber]

My main breaker has two switches that are hooked together and both switches have a 100 on the end so does that mean I have a 100 amp or two hundred, this is what is confusing me.

[Wgoodrich]

You have a 100 amp rated service.

Good Luck

Wg