I am doing a significant kitchen upgrade and the contractor has
recommended that I upgrade the electrical service to 200amp. I've had
3 electricians out to quote on the work---and received 3 very
different opinions and prices. Two have told me it is not necessary
to upgrade the main power line in the house from the meter to the load
center. The other one says I must.

I currently have 150amp service. The meter and the load center are
separated by about 50-feet. The wiring from the meter to the load
center is 2/0 aluminum. I work for a major residential electrical
equipment maker (starts with a "S" and ends with "iemens")...and our
construction sales people tell me that the latest version of NEC
requires 4/0 aluminum wiring for 200amp service.

What is up with 2 of these contractors telling me it is OK to upgrade
without replacing the existing 2/0 wiring?

Is there some sort of grandfather provision in this situation?

If the price difference wasn't so much it would be a no-brainer. But
at $3,500 vs. $750 it's a lot harder to go with the cadillac solution
simple because it is the cadillac solution....

Does anyone have any guidance on the issues and realities of this
situation?