How Do I Determine Electrical Svs Size (posted by Judy Thompson)

[ASKNACHI]This question was posted on by Judy Thompson (from San Diego, CA). [/ASKNACHI]How can you tell the size (in amps) of a service panel?

This is a visual inspection only.
If it is a main Disconnect is a breaker it will usually be in the center of the handle .
A normal small home could be 100 amps with a 100 amp panel .
The size of the panel should be on the out side of the box some where .
A newer home usually has a two hundred service .
The box should have marked 200 amps on it .
Now please look close as some 200 amp service boxes could have a 125 amp main breaker in this case the service is only 125 amps.
If the home has a fused disconnect then again the size of the disconnect is 200 amps please know it might only have 125 amp fuses inside so this would be a 125 amp service .
if the main fuse box is a 100 amp box then again the size of the service could be 70 amp service with only 70 amp fuses .
The size of wire in all cases should be large enough for the service .
This is usually more then most home owners can get to see and I would recommend you get a qualified person to verify the true size of the service .


There are several factors involved in determining the electrical amperage coming into your home. Instead of a long drawn out explanation, please go the the following site and it’ll explain everything you need to know in determining your amperage…

Everything Roy said is correct. Here is a simple summary.

The size of your electrical service is the SMALLEST of three different components. Those are: The size of the wire entering your electrical panel from the meter, the rated size of your electrical panel, the size of the main breaker or fuse.

So if you’ve got a 200 amp wire entering the electrical panel, an electrical panel that is rated for 200 amp’s, and a main breaker that is 200 amps, you then have a 200 amp service. If any one of those is different, your service is whichever is smaller.

Like Roy said though, you should probably get a qualified person to verify the size. There are other things to be concerned about, that an electrician would know to look for.