wire size and 200amp service

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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?
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On Wed, 27 Jun 2007 17:34:42 -0700, snipped-for-privacy@comcast.net wrote:

They are right
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snipped-for-privacy@aol.com wrote:

Does it require aluminum? If his current aluminum wiring doesn't meet the current code and will have to be replaced, should he be considering switching from aluminum at the same time?
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--Tim Smith

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Tim Smith wrote:

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.
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wrote:

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,

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wrote:

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.
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mm wrote:

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.
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wrote:

OK, I get it. Thanks a bunch.

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snipped-for-privacy@comcast.net wrote:

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: http://www.friesen.com/manuals/allowable_ampacities.asp#Single%20Aluminum%20Conductors%20in%20Free%20Air
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 risk.
Yours aye, W. Underhill
--
"Take sides! Always take sides! You may sometimes be wrong - but the man
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William Underhill wrote:

http://www.friesen.com/manuals/allowable_ampacities.asp#Single%20Aluminum%20Conductors%20in%20Free%20Air

You actually want table 4 (in conduit/cable) which has even lower amp ratings.

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 field studies.
4/0 can not be used for 200A non-residential services where major loads may be energized all the time.
-- bud--
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On Wed, 27 Jun 2007 17:34:42 -0700, snipped-for-privacy@comcast.net 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.
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Bzzzzt! Wrong answer, but thanks for playing. It absolutely is. 2/0 aluminum is rated at 150A max, per NEC Table 310.15(B)(6).
--
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Doug Miller (alphageek at milmac dot com)
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On Wed, 27 Jun 2007 17:34:42 -0700, snipped-for-privacy@comcast.net 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
http://hometips.com/articles/sunset_books/complete_wiring/calculate_electricalusage022.html
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 watts).
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Thanks this has been helpful...
EXISTING... 3,600 sq-ft = 10,800W range 15,000 dishwasher 1,500 fridge 1,500 disposal 600 laundry 1,500 dryer 5,500 water heater 5,600 --------------------------- 40,500W
(40,500-10,000)*0.4 = 12,200 + 10,000 = 22,200 (add 2 AC = 32,200W / 240 = 134amp
NOW ADD... 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 correct.
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On Wed, 27 Jun 2007 19:39:24 -0700, snipped-for-privacy@comcast.net wrote:

You're welcome.
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On Wed, 27 Jun 2007 19:39:24 -0700, snipped-for-privacy@comcast.net 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.
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On Thu, 28 Jun 2007 14:14:27 -0400, gfretwell wrote:

Need some overhead for future expansion so 200 would be a better choice IMO.
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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
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snipped-for-privacy@comcast.net wrote: [snip]

That is the minimum size rated for 150A.

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 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.

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)
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On Jun 28, 7:21 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Yeah, I couldn't figure out how this huge price difference could be attributed to replacing one 50 ft service run either.

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