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Doug Miller

In article . com, wrote:
[snip]
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.

That is the minimum size rated for 150A.

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.

They're right, and not just the latest version, either.

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

Either they're incompetent, or the wire is actually copper (doubtful). Per
National Electrical Code, minimum size feeder for 200A service is 2/0 copper
or 4/0 aluminum. [2005 NEC, Table 310.15(B)(6)]

Is there some sort of grandfather provision in this situation?

Not relevant. Whatever Code provisions may have been in effect when your
service was installed do not matter: upgrades must meet the Code that's in
effect at the time of the upgrade, not the time of the original installation.

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....

This isn't a Cadillac vs. Chevrolet situation -- more like Cadillac vs. rusty
tricycle. 2/0 aluminum is neither adequate nor legal for a 200A service, pure
and simple, and anyone who thinks it is should not be trusted to install a
service entrance.

The difference in price between 150' feet (50' run * 3 conductors) of 4/0 vs.
2/0 aluminum won't be much more than about a hundred bucks, if that.

The difference between the $3500 quoted by the guy who says you need 4/0, and
the $750 quoted by the guys who say 2/0 is acceptable, is at least in part the
difference between a qualified electrician and a couple of incompetent hacks.

If you're uncomfortable with the $3500 price (which does seem a bit stiff to
me), then solicit bids from other qualified electricians and compare.

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

There's no "guidance" involved on the size of the service entrance. The
reality is that using 2/0 aluminum for a 200A service is prohibited by the
NEC. Period.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.