We are in the planning stages of redoing the electrical in our house. We have lots of knob and tube wiring with a couple of runs of nmd 14/2 wiring which i am not sure where they go. Our meter head says it is 200 amp but our service panel is only 100 amp. We have central air and will be changing our gas water heater to an electric down the road. What determines if you need 200 amp service or 100 amp? Are we ok just to rewire the house properly with the 100 amp service or upgrade to the 200 amp service. Our house is only 1 1/2 story approx. 900 sq. ft.

Didn't you post this same topic on February 7th?
Your meter head may say 200 amp, but that doesn't mean that the service entrance cable will support 200amps. The cable in and out of the meter base needs to be sized properly. I'd put a 200 amp 40 space panel in just for the additional breaker capability.

The wiring withing the house would be the same regardless of what amp service you use. I would suggest however that you choose the 200 or perhaps at least a 150 amp service. It does not cost to much more to install but later on if you ever expand you will have the necessary power to do so. With all the new gadgets out there, we have become used to just plugging in. You never know what you will need in the future, so its best to plan that way.

Considering that the house still has knob & tube wiring, I'm betting that the service has been in place for a while. The cable between the meter base and panel is probably not sized to accomodate a 200 amp service. the cable between the service head and meter base is likely to be the same.

I would definately go 200 AMP. It will not only give you extra spaces in the box should you add on or need more power, say outside. Your major appliances should each be on their own separate circuit. You can and should isolate your computer, too.

One thing that was mentioned was the power supply coming into the house. However,theydid not tell you that your power company can change the wiring coming into the meter. Some to not even charge for this as it saves problms down the road. A lot of older homes do not have sufficent feed wire from the pole, the wire is too small to carry today's loads, thus causing brown-outs.

quote:

200 vs 100 amp

Have the electrician set a 200a disconnect on the post and a 200a
feeder to the house. (2/0 copper or 4/0 al) Your house is a sub
panel. You can just add another one to the feeder if the load
increases.

Of course your supplier owes you a refund or a new panel.
If you do get the panel upgrade your post and service will already be
OK for it.