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
That's certainly an option, but not essential. Aluminum wiring is not an
issue for these large gauges, it was only an issue when used in the
small gauge (14-10) general wiring in houses. It's mostly a cost and
personal preference issue as for service entrance use either is
perfectly acceptable. Note that the wire gauge required for a given
service size will be larger for aluminum than for copper.
I don't understand "personal preference". It looks good with my eyes?
I have stock in a copper company?
Are the only personal preference possibilities based on the
misunderstanding that aluminum in large gauges is not good,
Probably. There is really no problem with aluminum in aluminum rated
lugs. Some tests actually have shown that an aluminum conductor
performs better than copper in an aluminum lug. Most large lugs are
Aluminum conductors are more flexible than the equivalent copper
conductors and therefore easier to handle, especially for long pulls.
Copper conductors don't need to have anti-ox compound applied to the
connections. Current prices of each material come into play. The
physically smaller space occupied by the copper cable of a given current
rating can be a factor. Bottom line, personal preference as to which
issue are most important to you.
AL wiring in small gauges and terminated at devices without the proper
ratings is not good.
Hmm. Disclaimer first - I'm a naval electrical technician, not civilian,
so am not intimately familiar with civilian code requirements. Further,
I'm Canadian, and if you're not, some of your code requirements may vary.
That said, check out this website:
Depending on your insulation type and ambient temp, you'd need at least
3/0 to meet the requirements, and 4/0 gives you only a 30-amp safety
margin. As I said, I'm not familiar with the details of the NEC, but in
the Navy we'd be using the 4/0, since we have to assume that all loads
are energized at all times. There may indeed be some kind of
'grandfathering' provision, but I'd rather not create an electrical fire
"Take sides! Always take sides! You may sometimes be wrong - but the man
who refuses to take sides must *always* be wrong! Heaven save us from
You actually want table 4 (in conduit/cable) which has even lower amp
The US-NEC allows 4/0 Al for 200A residential services. In a residence
all loads are not energized at all times. The major loads, in
particular, cycle on and off. I believe the wire sizes were based on
4/0 can not be used for 200A non-residential services where major loads
may be energized all the time.
On Wed, 27 Jun 2007 17:34:42 -0700, email@example.com wrote:
I agree with the 2 that say it is not necessary, unless you are
changing from a gas stove to electric or adding large appliances like
a washer/dryer. You should already have 2 20A circuits in the kitchen
now. This allows plenty of capacity for countertop appliances.
In the unlikely event that you truly do need to upgrade your service
you can always do it later. It should not affect the kitchen remodel.
BTW Having quad receptacles and under counter lights are a good thing
to add while you are at it.
On Wed, 27 Jun 2007 17:34:42 -0700, firstname.lastname@example.org wrote:
This should ease your mind. Unless you are using more stuff than the
average 1800 sq ft home owner 150A service is plenty. This page came
up with total load of 110A
To understand how the formula works, consider the example of a house
with 1,800 square feet (based on outside dimensions) of finished
living space and space adaptable for future use. The house has the
usual two small-appliance circuits (3,000 watts), a laundry circuit
(1,500 watts), a hot water heater (5,500 watts), a clothes dryer
(5,600 watts), a dishwasher (1,500 watts), a garbage disposal (600
watts), a range (15,000 watts), and a central air conditioner (5,000
Thanks this has been helpful...
3,600 sq-ft = 10,800W
water heater 5,600
(40,500-10,000)*0.4 = 12,200 + 10,000 = 22,200 (add 2 AC = 32,200W /
240 = 134amp
2nd refrig 1,500W
2nd disposal 600
2nd oven 1,500
leave some spare capacity for eventually adding a hot tub at
& the 8" jointer I want to get for my woodworking shop (208V @ 20A)
Looks like upgrading to 200A for the new, added appliances is probably
On Wed, 27 Jun 2007 19:39:24 -0700, email@example.com wrote:
You can whack a big chunk of that 10,800va off of the general lighting
load. You only take the first 3000va at 100% and the rest is computed
at 35%. The "laundry" is also part of that calculation along with 3000
va for the kitchen small appliance circiuits.
Ranges are usually computed at 8000va
There is also an optional method where you take everything at name
plate value, use 100% of the first 10kva and 40% of the rest.
You can probably survive just fine on the 150a but you need a proper
load calc to be sure. In real life most houses do not consume anywhere
near the calculated load. If you do decide you really need 200a you
certainly will need the 4/0al or 2/0cu SE cable.
ahh just for the record that long 50 foot between meter and load
center can cause a voltage drop under heavy whole house loads.
myself if I were adding a addition then upgrading the whole thing is
what i would do, since its a small part of the overall cost and adds
resale value in the future
They're right, and not just the latest version, either.
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)]
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.
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
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.
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
Doug Miller (alphageek at milmac dot com)
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