Main Electrical feed into house

The drop size up to the service point at the mast or eave is up to the utility. It is usually 2 ga for everything up to 200a. From that point you have to follow 310.15(B)(6) 100a is 4ga cu 2ga al 200a is 2/0 cu 4/0 al
If the utility has upgraded from the 3 separated strands to twisted "triplex" it is usually 2ga and OK for 200a.

Is your service overhead or underground?

If you're gonna take the effort to upgrade at all, go with 200A. You'll have to add a second ground rod anyway, and bring the rest of the service up to code so the difference between 100 and 200A in terms of effort and cost are very little. The electric company is responsible for everything up to the meter base and you own the rest. I recently went through this process and upgraded a friend's house to 200A with a modern service panel. He had overhead power so I had to install a new mast with 2/0 copper conductors and 1/0 ground.

This is an international newsgroup.
Please give the location of this residence.
Not all countries, or even parts of them in some cases, have the same system.
-- Sue

Most people who are not in the US or Canada would be surprised at the need of anyone to have 200 amp service.

| |>This is an international newsgroup. |> |>Please give the location of this residence. |> |>Not all countries, or even parts of them in some cases, have the same |>system. | | Most people who are not in the US or Canada would be surprised at the | need of anyone to have 200 amp service.
Or even 400 amp or 600 amp. Seen both of those. They were big houses, so I guess the demand calculations were the driving factor for it. That and maybe they were electric heat, etc, too.

Just as a matter of interest, what is a typical domestic supply in Japan, where the Voltage is even lower? Does everything in the home run on 100V, or is there a higher Voltage available for high power loads?

| |> Most people who are not in the US or Canada would be surprised at the |> need of anyone to have 200 amp service. | | Just as a matter of interest, what is a typical domestic supply in | Japan, where the Voltage is even lower? Does everything in the home | run on 100V, or is there a higher Voltage available for high power | loads?
Everything for consumers in Japan runs on 100 volts, or 200 volts if it is a higher power appliance like a stove. I'm sure they have transformers available for the occaisional things from North America (120 volts) or Europe (230 volts). Products from Japan tend to work fine over the range of 100 to 120 volts, if not all the way from 100 to 240 volts. One exception of interest would be incandescent light bulbs. I've heard of at least one person who buys them from Japan and runs them on 120 volts. They burn out sooner but provide a nicer light for the short time they last. Not what you would use in hard to reach places. But it could be good for the chair side reading lamp.