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2-wire / 3-wire service #3615 08/23/01 06:13 PM
Joined: Aug 2001
Posts: 7,520
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pauluk Offline OP
Member
I was watching an old Cary Grant movie this evening ("Mr. Blandings Builds His Dream House"), and at one point they just happen to mention running a 220-volt cable for an electric stove.

That was back in 1948 and it got me to thinking. When did it become common for residential service in the U.S. to be 3-wire instead of just 2-wire 110-120 volts?

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Re: 2-wire / 3-wire service #3616 08/23/01 10:07 PM
Joined: Oct 2000
Posts: 3,961
Bill Addiss Offline
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Paul,

I don't know the answer to the question but I wisk I had a nickel for everytime someone thought to tell me that they "had 220" in the house, ... or for the times I've said "Everyone's got 220" [Linked Image]

Bill


Bill
Re: 2-wire / 3-wire service #3617 08/24/01 03:04 AM
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pauluk Offline OP
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Many people here know that their household voltage is 240, but that's often about as far as their knowledge goes!

By the way, I am right i thinking that the nominal official voltage is actually 117/234 volts? Do the utilities have a specified allowable tolerance? Ours is 6%. (To be more precise, it WAS 6%, but there's some changes going on at the moment. Explanations later, if wanted!)

Re: 2-wire / 3-wire service #3618 08/24/01 07:01 AM
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Posts: 311
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Frank Cinker Offline
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Paul,

The Power Company in Western Pennsylvania has a user tolerance of: +/- 5% for 120/240V,1Ph. and +/- 10% for >=230V, 3Ph

Re: 2-wire / 3-wire service #3619 08/24/01 07:30 AM
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Posts: 5,389
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sparky Offline
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I have only had the opportunity to change out a few very old 120V services , mostly on neglected buildings. The meter bases & main disco's were usually small, fed K&T, and became 'desktop trinkets' for those who admired their oddity.
[Linked Image]

Re: 2-wire / 3-wire service #3620 08/24/01 07:47 AM
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Posts: 2,056
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Redsy Offline
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It really depends on the region. I believe the 1940s began the increase in services. However, somewhere around 1988, I replaced a 120 Volt 30 amp service.

Re: 2-wire / 3-wire service #3621 08/24/01 09:43 AM
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Posts: 2,236
sparky66wv Offline
Member
My first ever rewire was from a 30A 120V to a 200A 120/240V...

That was about '85... (working with Hixson)

Haven't run across another though...


-Virgil
Residential/Commercial Inspector
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Re: 2-wire / 3-wire service #3622 08/24/01 02:36 PM
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Posts: 40
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glenn35 Offline
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Concerning 2W 120V services there are still quite a few here in Houston. Mostly in the oldest areas of the city. We even have some that are K&T and the tubes stick out of the wall with small #10AWG. There is no W/H just the tubes. These generally have "A base" type meters. Probably dates back to the 40's. Although these are still in existence, the cust is required to upgrade to current standards if any work to the meterloop is performed.

Re: 2-wire / 3-wire service #3623 08/24/01 05:35 PM
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pauluk Offline OP
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Thanks for all the info.

The lowest rated service I still see fairly reglarly is 40A (at 240V only, remember). Most of the older 30A services seem to hve gone now,certainly in this area. New sevices are generally 80 to 100A, but there are still a lot of 60A about.


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