residential electrical wiring in older home

I thought about buying an older home built in the 50's in around Houston, Texas but I was wondering about the electrical wiring.

a) does anyone know if aluminum wiring was used, when this area switched over to copper wiring?

b) briefly what advantages does copper have over aluminum?

c) without pulling off outlet/switch plates, is there an easy way to tell if the house has aluminum or copper wiring? Can aluminum wiring use a breaker box or only fuses?

d) for a 1 story 1500 sq foot home circa 50's, what an electrician might charge to switch wiring?

e) advice buying an older home with respect to electrical wiring?

Reply to
Doug
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I believe it was mostly used in the mid-60s through mid-70s, but I really don't know for sure.

It doesn't cause all the problems with corrosion, poor connections (due to thermal expansion/contraction), and subsequent heat/fire due to the resistance of the poor/corroded connections.

I'm not sure that there is a reliable way to tell without actually seeing the ends of some wires. I would ask if the home moaner would let you remove the cover to the breaker box.

I don't know, I do pretty much all electrical work myself.

Also check for grounding. About the time frame you mention is when grounded Romex was introduced. Older houses may use ungrounded "rag" wiring which while perfectly safe if in good condition will not provide a grounding conductor which you'll really want to have to protect today's electronics (lots of "surge strips" rely on the grounding conductor to provide a path for diverted surge voltage.) I had a house built in '47 or '48 w/o ground. Grandmother's house built in mid-50s had ground, although non-grounding type receps.

Presence of grounding type receps and good test with pocket tester is no assurance of proper wiring. My old house was "faked" with the ground terminal bootlegged to the neutral at the receps, not legal, but it was done - as I discovered to my chagrin when I started replacing old, worn out receps that wouldn't hold a plug anymore. Not an easy fix.

nate

Reply to
Nate Nagel

Not likely that any of the smaller conductors would be aluminum. Possibly the larger conductors like the service entrance, range circuit, central air circuit, or electric dryer circuit, may be aluminum. There is no problem with larger aluminum conductors, only the 12 and 10 gauge, that was used for general lighting and outlets. You should be able to ask the seller, or broker to find out what's in the house. Unless the cable is type AC (BX), there is a possibility that it's non grounding Romex, which can be a pain in certain circumstances, none of which should prevent you from buying the house.

Reply to
RBM

The Al branch circuit wiring craze was generally in the mid-60s; the chances of it in a 50s house are nil.

Al tends to oxidize and has higher thermal coeff of expansion so tends to loosen connections w/ time more than Cu. The biggest issue is the oxidation layer and contact resistance at connections that acts as a miniature heater and eventually can reach combustion temperatures if gets bad enough.

You'll have a home inspection done, anyway, wiring is just one of the many issues to have verified and discover if there needs to be either work done prior to the sale or discount the offer to cover the cost to yourself after the sale.

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Reply to
dpb

If you are considering purchasing the home make it non-negotiable that an inspector of your choice address your concerns beforehand. If that is rejected then walk ... no run, they are hiding something.

As a former substation transformer designer I assure you there are only two ways of making reliable connections using aluminum conductors. One is to acid treat, copper plate the aluminum, and then bolt aluminum to copper bus bars together. Inside a transformer this connection is submerged in oil and can still fail. Aluminum to aluminum connections must be welded together to be completely safe. Obviously you will find none of that in household wiring. Crimping or twisting aluminum to aluminum or aluminum to copper connections will eventually fail due to corrosion.

HTH, John

Reply to
John

Not exactly nil, but pretty close. As with a number of electrical materials, some things were available long before anyone cared to use them. Small gauge aluminum building conductors were around since the

40's, possibly because of the war, but the era of aluminum wiring that strikes fear in homeowners, is primarily from 65' to 73'. Sometimes earlier conductors with tinned copper is mistaken for aluminum.
Reply to
RBM

The vast majority of residential electrical services use aluminum conductors. They're generally clamped down in set screw connectors using a little anti-ox paste, and hold up just fine.

Reply to
RBM

Not sure how it works in the OP's area, but no home inspector that I've seen is going to remove the cover to the breaker panel and/or a recep cover plate. All they can do is plug in a tester and make sure that all the right lights light up.

nate

Reply to
Nate Nagel

The home inspector I just hired took both covers off and took pretty pictures to go in the scrap book he put together of the house. ;-)

Reply to
krw

About 7 years ago I bought a house and the inspector took off the breaker panel cover to check the wiring. I watched him do it and then he went around with the plug in tester . I did not have to have the house inspected, but I thought it was a good idea. I was not worried about the small things he found, but needed to see if anything major need work. This was in the middle of North Carolina.

Reply to
Ralph Mowery

Yes, the house we just bought (actually, closing is next week) is in very good shape but it's a foreclosure (Fannie owned) and it wasn't a major decision to spend $350 for someone to spend a few hours looking for things I missed in the, maybe 1/2 hour I'd spent looking at the house. He did find a few things that I'll want to take care of quickly but nothing major. He did find that the water heater was burned out. The morons who Fannie hired to winterize the house didn't turn it off before draining it - poof!. We got her to fix that problem, since they caused it.

Reply to
krw

A big share of underground wiring for irrigation systems/wells is aluminum. That wiring supplies power to the three phase motors. The motors for the wells are usually 3ø 480 VAC. Most are 50 to 100 hp. There aren't that many failures in the actual connections at the panels. Most of the ones I've seen are caused by rodents or lightning. I don't know if I'd want AL house wiring but it works well where I've seen it used. Anti oxidant and proper connectors seem to make it ok.

Reply to
Dean Hoffman

Both the inspector that did the inspection before I bought my house and the one that did it for the eventual buyers said that they weren't

*allowed* to do so. State law, or just some kind of organization thing? I don't know.

I really wish the first guy would have done so however, I would have negotiated down when I saw that the "updated wiring" was an illegal hack job.

nate

Reply to
Nate Nagel

The wiring itself isn't bad but the connections to typical light fixtures, receptacles, etc. certainly can be.

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The OP is correct to be concerned.

nate

Reply to
Nate Nagel

Sounds bogus to me, unless you live where it requires a union thug to wipe your bottom. I'm pretty sure all the inspectors I've used when I've bought have pulled the entrance panel. One of the houses I sold was to a relocation company. Their inspector pulled the panel cover during his inspection, too (I had to replace the "tied" breakers).

It's such a simple and important thing.

Reply to
krw

I agree that connections are the problem. As RBM said, the problem is esentially only with #12 and #10 wire on 15 and 20A branch circuits. Aluminum is in common use in larger sizes.

About 1971 UL removed the listing for wire and devices (receptacles, switches,...) then came out with new standards. The new devices were marked "CO/ALR". According to gfretwell the new wire was harder and not as likely to extrude/creep. (Most of the wire in use is "old technology".)

The CPSC appears to have been moving toward a recall (which would have been enormously expensive), but in the inevitable court case wiring was ruled to not be a "consumer product" and thus not under the purview of the CPSC.

If anyone is dealing with these aluminum branch circuits, recommendations on making connections, based on extensive research done for the CPSC, is available at:

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basic element is cleaning the wire to remove the oxide and applying antioxide paste.

Reply to
bud--

I have a tester I got a long time ago that can find a N-G connection at the receptacle. It puts short relatively high current pulses H-N (if I remember right) and looks at the N-G voltage. The tester should see voltage drop on the neutral wire. It can also test if there is a good ground connection (again with a short pulse - to ground).

A 3-light tester with GFCI test is essentially the same as a 3-lite tester. If it tells you there is a problem there very likely is. They won't find a lot of problems. For instance they can't reliably tell you there is a good ground connection. Or G connected to N at the receptacle.

IMHO it is not a good idea for a rather untrained person to remove a panel cover. It may be an OSHA violation - the person is not likely a "qualified person". The hazards of not just shock, but arc-flash, are not adequately appreciated.

Reply to
bud--

On 3/24/2012 6:14 PM, RBM wrote:

A lot of early copper house wiring was tinned because connections were soldered then wrapped with friction tape. I've found this in a lot of older homes during remodels and the insulation appears to be tar impregnated cloth which will often crumble away when disturbed especially if it's been exposed to heat as in light fixtures. I worked for an electrical supplier in the early 1970's during the oil shortage and a copper shortage when many electrical manufacturers switched to aluminum for Romex and they added a lot of fillers to petroleum sourced plastic insulation to keep the electrical industry alive. I was glad I owned a car that had an 1108cc engine during that time. The problem with aluminum house wiring showed up even then because the manufactured housing industry was using a lot of it and when the trailers bounced down the highways for delivery, the aluminum wiring had a tendency to fail because it lacked the ductile properties of copper and could not tolerate mechanical and thermal stress the way copper could. Electricians of the day weren't used to working with small aluminum conductors and the connections would often burn up setting homes, especially mobile homes on fire. Over the years I've found a lot of failed connections in aluminum Romex and had to add the special connectors and copper jumpers in order to replace damaged wiring devices. The special connectors containing antioxidant grease are available at most home improvement stores and you can use them to add copper jumpers to your aluminum house wiring.

TDD

Reply to
The Daring Dufas

I bought the house I'm currently living in in 1987. It was built in

1970 and has aluminum wiring. At the time of sale I required the seller to swap out every wall receptacle and switch with COALAR units and the work to be done by a licensed electrician.

Every house in my subdivision was built at the same time with the same wiring. Neither me nor any of my neighbors (to my knowledge) has had any problems related to the aluminum wiring. We all have circuit breaker panels.

I used to take off the face plates every year and check to see if the wire loops were loosening under the screw heads but gave up that exercise after about 3 years when none were noted to have become loose.

I'm well aware of the supposed risks associated with aluminum wiring and I would have preferred to have copper. However, my experience has not been bad. I suspect that if the homeowner respects the amperage ratings of each breaker circuit and avoids overloads, they will not have problems. Copper is more forgiving of overloads due to lower resistance and therefore less heating and attendant expansion/contraction at connections.

Reply to
Peter

Thanks Peter. What is COALAR switches? As best as I could see on the net it's copper aluminum automation ready switches and I have no idea what that means? One thing I've learned is that this house "supposedly" per the owner has copper wiring but personally I don't trust it to be so unless I can verify it. He did say that in the early 90's it has a small fire on the roof at the garage end of house due to a lightening strike. I don't know if that has any connection to the wiring and since I don't know this owner, I'm suspicious to say the least.

Reply to
Doug

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