Trying to find what is the resistance difference between aluminum and copper wiring when being used for household electricity. The original owner ran two 4 gauge aluminum wire from the meter to the fuse panel, about 100'. I know aluminum wire has a higher resistance than copper, but would it be enough of a resistance to be worth swapping out the aluminum wire for copper. A google search only turned up the differences for transmission lines, not household lines.

Aluminum is about 1.5 x the resistance of copper.

If the Aluminum is doing the job there isn't much reason to change.

If you want to investigate further, some info to help...

4AWG = 21.1mm^2 cross sectional area

To work out current an projected voltage drop along length of cable.

Voltage drop = I À R = I À (2 À e À rho / A)

metal spec. resistance
copper......... ........(rho) = 0.0178
aluminium...... ........(rho) = 0.0277

I = Current in ampere
e = Wire length in meters (times 2, because there is always a return wire)
Rho = specific resistance (Ohms for 1 m length and 1 mm2 cross section area of the wire)
A = Cross section area in mm2

HTH

Aluminum wire dangerous

You make the call
Russ

It's most likely you'll want to swap all that out. I know Ted spent a lot of $$ replacing the AL wire down at his place.

Your building inspector or local electrician will probably tell you that it's not to code anymore. DO ask!!

From what I have found you need double the gauge aluminum as compared to copper, i.e., the 4 gauge which is/was code, should be 2 gauge because it is aluminum.

The electric bill has always been high for a home(2250sq.ft) w/o central heat and air, and averages about $200/month w/wood heat/fans in the winter, and $300+ during the summer w/a swamp cooler/fans and an irrigation pump. Nothing I have done seems to lower the bill any. Every light is fluorescent, doubled up the insulation in attic and the house has the vinyl siding which has its own 1" layer of foam padding behind it, the house stays warmer and cooler, but no difference in electric bills.

I have been contemplating replacing the aluminum wire for a while now, but after PG&E came by last week and installed one the smart meters, I can actually observe when and how much power is being consumed and correspond it to the activity that is taking place. It has been unseasonably cool, and w/o running the swamp cooler I am consuming 30-35kwh's/day depending on how long the irrigation pump runs. However w/everything off during the night I am still consuming 7kwh's which amounts to the 1/3 the alloted base rate/day. All that is on during the night is the refrigerator and a freezer, both less than 6yrs old, a small fish tank pump, a small decorative pond pump, a pc fan, and a few digital clocks. There isn't any difference w/the pc and the pond pump off.

I figure it will run about $3-400 run copper wiring(haven' priced the wiring yet), and I am trying to determine if the savings are going to be worth it. Based on last years total usage, a 1% savings would only save me about $50-60/yr off of my bill. I am not sure that really warrants swapping the wire, however 5% or more and would be a significant yearly savings.

60m of 4 AWG cable (copper) is 0.051 ohm, and at 50 amps peak it would dissipate 2.5 watts over its length

Aluminum would be fractionally more than that, still less than 4 watts.

Maxed out at 50 amp continuous for a year would be 35kWH. I don't know the price of power over there but here it's about 25 cents per kWH, which makes it less than 10 bucks.

In essence no savings would be made.

Heat dissipation would not be noticeable and thermal stresses would be absent, therefore presenting no fire risk, assuming no interruptions to the continuous line were made (as described in post above re safety of aluminum).

Unless there's a high resistance loss at the terminations of the Al wire.

PG&E rates are tiered by usage, $.12/kwh for the base(603kwh/30 days), then 101-130% over base is $.14/kwh, 131-200% over base is $.29, and 201-300% of base is $.40.kwh. They also have off peak, peak, and semi peak times, which w/the smart meter they will now be able to charge accordingly, since they have to pay(themselves) more for power during peak usage times than when off peak.

Would the age of the age of the aluminum wire have a greater impact on the bleed off? The wire which doesn't appear to be sheathed, is at least 32yrs old, and could date back as far as the 1930's. The land the home is on now used to have a Grange Hall on it, until it burnt down in the early 1950's.

A bigger consideration is the quality of the AL to CU connection.

As noted, AL wire has been phased out in residential apps. However, a lot exists.

The noted issue with AL is fires attributed to connections.

If faced with the option of replacing AL wire for CU, consider the mundane acts of redoing the connection between AL and CU.

There are a number of dielectric compounds that promote this action.

Do your homework and look at AL - CU connections.

I think you mean antioxidant.

Aluminum is very common for drops and for going from the meter to the breaker box. The problem was when it was used for general wiring. The connectors at wall sockets were not robust enough to handle the CTE mismatch.

Over the years better aluminum alloys and sockets have been developed. But they are not common for wiring from the panel box to the wall.

This should not be an issue on the type of connections used on a breaker box and a power meter. Those are a much more robust connection that deals with a CTE mismatch a lot better than the connections that originally were used past the breaker box.

IF your panel is rated CU/AL your fine. Inspecting the connections to make sure they are tight never hurts. Same goes for the connections at the meter head. If your worried paying an electrician to inspect your setup might be worthwhile.

On general wiring you would need sockets and switches rated CU/ALR. Since you only have aluminum on the service run that's not an issue.

I'm guessing that you have a 50 amp service? That might be a reason to upgrade.

Cable Brochure

Kevin