Opinions about aluminum wire for service main to shop

[Bill Dufour]

I am aware of the problems of aluminum house wire from the 1970's. Supposedly they have solved the problems and it is safe to use if you buy the Al rated devices.
How do you feel about running aluminum feeder wire, in buried conduit to a shop for say 75 amps. Is it worth the risk. is it cheaper since I assume the connectors at each end will cost more. Actually I think all the big breakers and sub panels of that amp range are already Al/Cu rated. There is no way I would consider it for wiring in the wall for low amps.
Home depot has huge wooden reels of big copper that they do not have listed as selling. They have huge reels of Al cables they do admit to selling and even give prices for them.
Bil lD

[Aaron Rosenthal]

There may be something in your local codes about aluminum, whether it's allowed or not.
Why not ask your city electrical inspector's department abut your plan?
They might insist you pull a permit, but then you get an inspection that makes sure if there's any problem down the road, your house insurance is valid.

[Brice Rogers]

Bill, I think that before I made the decision that I would consider the difference in cost. If the run isn't all that long, then I'd probably go copper. I suspect that #6 wire might be okay for 80 amps. #4 might be a little better. If it is a moderately short run, say 50 or 100 feet, then copper might be fine. But it you're talking about several hundred feet, then the economics of Al might prevail.

Make sure that you use the special Aluminum fluid/oil on the joints to prevent oxidation. I've used some stuff called No Ox, but that was years ago.

[Bobby Robbinett]

I used aluminum feeder wire to make a little under 100ft run into my shop if my memory serves correct. I have a 400amp service at the moment and soon to be upgraded to 1200amp service. I never had any issues with voltage drop or current issues according to my electrician. Mine is 3phase.

[Tom M King]

No issues with service entry wires.

[roger wiegand]

All the wires leading to your house are likely aluminum, every service entrance I've ever seen was aluminum. I'd pull oversize wires in case you decide to upgrade equipment in the future. I pulled a 100A subpanel to the shop and I find I'm pushing it sometimes now-- if I forget and turn the dust collector and RPC on at the same time the lights seriously dim. It would only have been a few bucks at installation to upsize the wires, now it would be a serious pain.

[Tom M King]

We have hundreds of yards of the direct burial stuff here. Unless you have sharp rocks in your soil, I don't see any reason to put it in conduit.

[Robert Engel]

I am not an electrician, but I had a buried aluminum feed to my shop that lasted 20 years, and suddenly I lost a hot leg. The electrician investigated and found a break. There are no rocks in the soil, nor tree roots anywhere around.

He told me it just sometimes happens the insulation gets a break and the aluminum oxidizes and eventually corrodes. We fixed that and about a year later I lost the neutral.

We replaced the whole run but put it in conduit.

I eventually had a dedicated service run to my shop/barn, it was in conduit buried 3' deep. The electrician told me it was required by code regardless of the type of wire. I asked him about copper and he said it is too expensive and there is no advantage.

[Ole Anderson]

A few years ago we had a primary wire from the pole to our pad transformer at work go out. The utility lineman said that it is not unusual for underground wires to fail after 20 years. Fortunately they were in conduit so the replacement was easy. I have had to replace my underground RG6 cable from the pole to the house at least three times. Each time was worse due to more and more roots. I finally installed a 3/4" conduit with RG11. Now if it fails I won't be digging up my yard again. Moral of the story is that unless you don't mind digging up your yard, put everything in conduit. I will say though that my 200 amp underground service from the pole to the meter is direct bury and is now 45 years old.

[Steve Rozmiarek]

All the wires leading to your house are likely aluminum, every service entrance I've ever seen was aluminum. I'd pull oversize wires in case you decide to upgrade equipment in the future. I pulled a 100A subpanel to the shop and I find I'm pushing it sometimes now-- if I forget and turn the dust collector and RPC on at the same time the lights seriously dim. It would only have been a few bucks at installation to upsize the wires, now it would be a serious pain.

This, but keep in mind that it's all part of the system, you need to have the correct size breakers and lugs at all steps of the system, so if you put an oversize wire in in one place, the it might force you to just start with a bigger subpanel. Your insurance company will not hesitate to deny coverage if your DIY causes a fire. Highly recommend a licensed electrician do service drops and panel installs. It's one thing to run another circuit, it's a completely different thing to be liable for sizing feed wire wrong for the next guy that doesn't know he's doing. The use of a licensed electrician is for liability protection.

[lowell holmes]

Aluminum wire should be avoided. It has issues you do not want.

https://www.google.com/search?sxsrf=...=2133&bih=1076

[Tom M King]

Lowell. They're talking about house wiring. That's the kind of thing that keeps bringing up questioning aluminum wiring of any kind, by people that don't understand the whole picture. There is no problem with using Aluminum for service entry wiring. I'm sure there are many electricians that have never used anything but aluminum service entry wire.

[Mike Cutler]

Bill

There is nothing wrong with running aluminum service entry cabling. There a millions and millions of installations in service today all over the country
The issue with aluminum wiring primarily involved the inter connection wiring in a dwelling, or business. This is the smaller single conductor 10/12/14 awg wiring.
The causes were the unanticipated galvanic corrosion effects at the fixture terminations inside the gang boxes. The copper, brass,nickel clad copper and stainless steel screws and yokes accelerated the issue. Aluminum NMC wiring was removed from the code books back in the late 70's early 80's
There are multiple type of service entry wiring. You just need to make sure that you are using the correct type. Many of them are aluminum, and there is an anti oxidizing paste/grease, that will be applied at all connection and transition points when using aluminum conductors.

The positive to running service entry cabling in conduit is protection, future upgrade capability depending on conduit size, and there is no transition inside the house.
The downside is that the conduit sizing and stuffing is gauged on the circular mils of the cable. If it is flat cable the circular mils requirement may be a penalty requiring a much larger sized conduit. Regardless of type of cabling, pulling it through conduit is not an easy job.
Another negative aspect maybe how many degrees of conduit run direction change will be required, and how many will the inspector allow, and will they count the entrance sweeps toward the penalty.
PVC conduit burial requirements are 21" to the top of the conduit. Direct burial is 24". By the time you dig the trench to lay the PVC conduit, you've already dug the trench for direct burial. Something to consider.
Regardless of which way you go, drop a dedicated conduit in the trench for low voltage wiring. The trenching is the real work. Don't set yourself up to do it twice. This is also the reason everyone that has done it, will tell you to pull larger gauged conductors or cables than you think you might need. Nothing is worse than pulling for 60 amps and 5 years later you find a need for 100 amps. I personally would pull for at least 100amps.
Transitioning from THHW to NMC inside the house can be a pain. Everything depends on what is acceptable in your area. Split Nuts, and tape. Can you use Polaris nuts? etc. Run the conduit to the boxes? Then fire stop requirements for the conduit coming through the exterior walls. It's impossible to know what is required in your area.
Before you buy your cabling from Home Depot, check out an electrical supply house. You may find it actually cheaper than home depot.

Research your project, and consult with the building inspector.

[Mark Bolton]

Everyone will opt for aluminum when comparing it to copper. In my area you have to run copper for a 400A service drop (with the utility clamps onto with aluminum so the only copper is whats running down the mast from the weatherhead to the meter base but they make you run copper because the aluminum conductor size would not fit in the utilities crimps). I would agree running it in conduit is reasonable insurance but as Tom mentions direct burial is common though conduit gains you a shallower trench if that matters.

The price jump to copper on service conductors is massive. Stick with the aluminum, grease the heck out of your terminations, and go on.

[Mike Henderson]

For running less than 100 amps to a shop, I'd opt for copper unless it was a long run that made the cost prohibitive. I admit this is based on my prejudice against aluminum wire.

I put in a 100 amp subpanel not too long ago and chose copper - but the run was fairly short - less than 30 feet, if I recall correctly.

Mike

[A house I had in Florida had aluminum from the meter to the service panel. One day the main breaker tripped. In checking it, the breaker was hot. The connection between the aluminum wire and the main breaker had developed a resistance joint - the heat caused the main breaker to trip. I had that aluminum wire replaced by copper and never had another problem. Yes, I know the original installation was bad but with copper I didn't worry so much.]