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=ALeKk02K76A8HKwWcSokOA_jyB-lTiBp0g:1611929207767&q=aluminum+wiring+issues&spell=1&sa=X&ved=2ahUKEwjLjdOeqMHuAhVKa80KHeNhBfkQBSgAegQIHxAw&biw=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.]

[Tom M King]

Every new house I built, from the first one in 1974, to the last one in 2007, had direct burial aluminum service entrance wire run from the pole to the meter, and from the meter to the main panels. Only one was put in conduit, and that was because the ground there had a lot of sharp rocks in it. All the others went into plain red clay subsoil. Not one, that I know of, ever had to be replaced. They're all within a fraction of a mile of my house, so not likely that I wouldn't hear about it.

I did put a large conduit in the ground to run a hundred amp feed down onto our point, knowing I might want to run something larger, later. Conduit is cheap, and certainly won't hurt anything, but it is something else to do, and it's not easy pulling a heavy wire through a long run.

While you have the trench dug, put an extra run of 1-1/2" black polyethylene pipe in it, for something you forgot about later, or something that hasn't been invented yet. I still get people coming to thank me for doing that on the houses I sold. Conduit will work too, but you have to remember which way is the best way to pull the wire, because of the way the joints are. Black poly can be bought in long, continuous lengths. I pull mason's line, tied to a little piece of rag, with a vacuum cleaner. Any time you pull a wire with that line, pull another line for the next thing.

[Bruce Wrenn]

Both of our houses have a 200 amp services and copper service conductors, BUT! The longest run is less than 6 feet, so copper wasn't that expensive. On second house actually bought copper at scrap yard in Virginia Beach when I was working there. #6 has a rated working capacity of only 60 amps because that's what the connecting devices are rated at. "Bug" it over to #4 at each end, and rating goes to 75 amps.

[John K Jordan]

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 base 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

I also have a prejudice against aluminum wire, especially underground, based on my reading and my own experience. I had a long (650'+) underground feeder fail after years. It was installed properly with and bedded in sand. Professional speculation was the cable was defective. I dug a new trench and replaced the line with copper in conduit. Yes, 650'+ of copper was not cheap but I don't want to have do it again.

When building my shop I ran oversized copper about 250' underground in conduit for a 100amp panel. Yes it was an expensive installation even though I did every bit of it myself. But the extra for the wiring was only a tiny fraction of the total cost of the building. I decided the extra expense of copper was far less than having to replace it at some future time.

JKJ

[Tom M King]

For long pulls, I've found it's easier to pull the conduit over the wire, than to pull hundreds of feet through a conduit. I'll slide the first piece on, outside the ditch, and glue another piece on, and another, until you feel that it's all you want to pull at one time. Pull that one all the way to the end, and then do as many sections like that as it takes. Slide it over into the trench once it's all together.

The last time I did that, it was going downhill about 350 feet, by myself, and it wasn't too bad. Pulling heavy wire through that much conduit would have been a Lot more work for one person. That was hundred amp wire in 3" plastic conduit.

I can't think of a good reason why an aluminum conductor would fail quicker underground than a copper conductor would. I have heard of a lightning strike taking one out, but can't see where the conductor metal would have mattered. It seems like the insulation quality would be the most important thing. Southwire, made in the USA, is the brand I've always used, sold by an electrical supply company. I'm not sure what the box stores sell.

[Mark Bolton]

I can't think of a good reason why an aluminum conductor would fail quicker underground than a copper conductor would. Same reason why you have to use no-alox or any other anti oxidant on the connections. When the slightest break in the insulation creates a miniscule current leak to ground you have a corrosive condition with aluminum. Its why many say conduit is actually worse because its not uncommon for glued pvc conduit to fill with water and the conductors are submerged.

I too have never had a problem. But there is a serious voodoo situation with aluminum and DC power which technically has some effect on AC as well and aluminum/wet/damp/electricity can be an issue.

My guess has always been some rough handling of the wire or an issue with the insulation in manufacture that allows a crack/break in direct burial that causes an issue. That said, I too have run miles of direct burial aluminum without an issue. And I too use the technique you mention. String out the wire whenever possible and walk a joint down the wire, glue it, and repeat. Far easier than juicing the conduit with lube and using a pull rope and winch to drag through a long run thought that too has to happen often.

Every single underground we did here, the utility wanted conduit and a nylon pull rope and they poured a gallon of lube in, and just ripped the stuff through with a hydraulic winch.

[Alex Zeller]

I ran aluminum wire to me detached garage for 100 amp service about 15 years ago. I put it in 2 1/2" pvc conduit that was left over from building my house (overkill). The problem with aluminum is that it has to be larger to carry the same amperage as copper. For example 12 awg copper wire is a standard for 20 amp service. You have to drop down to 10 awg in Aluminum to do the same. Also aluminum will oxidize much easier than copper. That's why a no oxidation agent is required on aluminum.

[Frank Pratt]

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

https://www.google.com/search?sxsrf=ALeKk02K76A8HKwWcSokOA_jyB-lTiBp0g:1611929207767&q=aluminum+wiring+issues&spell=1&sa=X&ved=2ahUKEwjLjdOeqMHuAhVKa80KHeNhBfkQBSgAegQIHxAw&biw=2133&bih=1076

That kind of a blanket statement is about as wrong as saying you should never use copper because it too can fail.

[Marty Gulseth]

I'll share some experience anecdotally, as folks here have already expressed opposing opinions.

First - someone pointed out that sometimes, local codes may specify copper conductor, and that's the first thing to check.

As to aluminum wire - I'm a retired electrical engineer, and I spent the last eight years of my working career as a standards engineer specializing in underground distribution at a local electric utility. They were using aluminum conductors almost exclusively (about 90% of installed plant) long before I got that job, and I never saw or experienced any reasons to change that selection. This was including primary distribution cables carrying load at voltages up to 24 kV, and currents up to 600A. Now the early generation primary cables did experience extensive failures, but those were due to impurities in the dielectric (insulation) portion of the cables and not-yet-refined manufacturing tolerances. Cables manufactured since the late 90's were, when properly installed, essentially "bulletproof". During my tenure as a standards engineer, I was involved in investigating probably a half-dozen "cable failures". Upon close examination, the cable itself NEVER failed - all the issues were determined to be due to either old generation poorly designed terminations (connectors, but the devices are more than just a connector at those voltages and currents) or, the majority, poor workmanship when installing the terminations.

For myself - my recently purchased home, with detached shop, has aluminum conductors underground out to the shop, landed at both ends into AL/CU rated panels, and I'm pretty sure the underground service from the pole into the panel in the house is also aluminum. Based on my above experience, I have absolutely no problem with the aluminum conductors, and if I had it to do over, I'd install aluminum (AND properly rated termination equipment!) without hesitation. My two cents worth.

Regards,
Marty

[Bill Dufour]

Only talking 30-40 feet so sounds like the copper is not too much more expense. I was interested to see that HD does not admit to having anything bigger then #6 in copper. Even with big wooden reels of copper too trip over getting to the Al reels, it does not exist. I also saw thy have dumped all the cheap blue PVC boxes in other then single device size. They have switched to a gray plastic boxes at 3x4 times the cost. Still have big empty shelves in the electrical department.
Bil lD

[mike stenson]

Interesting thread.

I don't think I've seen anything other than Al for service entrance. Ever. Including underground, direct burial. I've also not heard of common failures.

[Mark Bolton]

Only talking 30-40 feet so sounds like the copper is not too much more expense. I was interested to see that HD does not admit to having anything bigger then #6 in copper. Even with big wooden reels of copper too trip over getting to the Al reels, it does not exist. I also saw thy have dumped all the cheap blue PVC boxes in other then single device size. They have switched to a gray plastic boxes at 3x4 times the cost. Still have big empty shelves in the electrical department.
Bil lD

Here your talking like $2 a foot for AL and $7-8/ft for Cu.. 40 feet at $5 a foot isnt cheap to many but I agree its not the end of the world

[David Davies]

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.

1200 amps...I have amp envy.
Dave

[Walter Mooney]

Not to hijack this thread, I've enjoyed reading the back-and-forth. I'm building a new second shop in the TX Hill Country, and will have a 100-amp service in it, about 100' from the incoming power pole. I plan on pulling three #3 conductors and a #6 ground -- all copper, in a buried conduit. What type or designation (if that's the right term) copper wire to I want? THHN? THHW?

Thanks in advance for your help with this.

[Mike Cutler]

Not to hijack this thread, I've enjoyed reading the back-and-forth. I'm building a new second shop in the TX Hill Country, and will have a 100-amp service in it, about 100' from the incoming power pole. I plan on pulling three #3 conductors and a #6 ground -- all copper, in a buried conduit. What type or designation (if that's the right term) copper wire to I want? THHN? THHW?

Thanks in advance for your help with this.

THWN. The W stands for water resistant. All underground wire and cabling has to be rated for water. Even if it is in buried conduit.

[Robert Hayward]

Two pictures of the same aluminum wire. This came from a house built in 1970. 100 amp service with about a four foot run from the meter can to the breaker panel, almost on the other side of the wall from the meter can. Power kept going on and off intermittently. The two lugs on the homeowners side of the meter were both burned and both hot leads to the beaker panel were like the one pictured. The covering on the wires is bubbled from getting too hot. How close was that to a house burning down?

Could not see any evidence of anti corrosion paste having ever been used on either end of the wires. That cost ~$1500 about ten years ago when the house was 40 years old. I am not against aluminum, too many homes in the States use aluminum for the main feed. Just has to be installed correctly. The wire pictured hangs on the wall beside the panel as a reminder. The wire was replaced with copper, btw.

[Mike Rambour]

when I built my shop, electrician ran Aluminum wire to the 100amp sub-panel in the shop, its in conduit so should be good to go with no damage from roots/etc. I was not too happy when I found out he ran aluminum but it passed city inspection as everything was done with permits, so must be ok. Copper in the walls of course.

[Doug Dawson]

Two pictures of the same aluminum wire. This came from a house built in 1970. 100 amp service with about a four foot run from the meter can to the breaker panel, almost on the other side of the wall from the meter can. Power kept going on and off intermittently. The two lugs on the homeowners side of the meter were both burned and both hot leads to the beaker panel were like the one pictured. The covering on the wires is bubbled from getting too hot. How close was that to a house burning down?

Could not see any evidence of anti corrosion paste having ever been used on either end of the wires. That cost ~$1500 about ten years ago when the house was 40 years old. I am not against aluminum, too many homes in the States use aluminum for the main feed. Just has to be installed correctly. The wire pictured hangs on the wall beside the panel as a reminder. The wire was replaced with copper, btw.

Noalox was required for aluminum wire back in the 70’s, but (as I recall) for decades now the aluminum alloy approved for wiring has been such that it is no longer needed. Source, for me anyway, was one of Mike Holt’s seminars a few years ago. BTW and FWIW, even his book on electrical theory gets this wrong, to his surprise. :^)

[Jim Becker]

At the time I had our property service upgraded and the 200 amp feeder to the shop building installed, the price of copper was sky-high and the electrician and I decided to go with aluminum feeder for the approximately 100' of run in conduit under the ground. The conduit had to be a little more generous, but this was perfectly acceptable and compliant with code. Aluminum feeders are common and safe when installed properly.

[Ron Selzer]

Two pictures of the same aluminum wire. This came from a house built in 1970. 100 amp service with about a four foot run from the meter can to the breaker panel, almost on the other side of the wall from the meter can. Power kept going on and off intermittently. The two lugs on the homeowners side of the meter were both burned and both hot leads to the beaker panel were like the one pictured. The covering on the wires is bubbled from getting too hot. How close was that to a house burning down?

Could not see any evidence of anti corrosion paste having ever been used on either end of the wires. That cost ~$1500 about ten years ago when the house was 40 years old. I am not against aluminum, too many homes in the States use aluminum for the main feed. Just has to be installed correctly. The wire pictured hangs on the wall beside the panel as a reminder. The wire was replaced with copper, btw.


copper wire will do the same thing if ends are not terminated properly, or too much load as in a breaker that has internal issues(too much voltage drop) but still appears to work ok
Ron

[Ken Fitzgerald]

I have a separate power run to my shop. The utility company ran aluminum to the mast of the service entry. It attaches to my supplied copper and goes inside to the service panel in the building. Everything in my shop including the feed to the 200 amp panel is copper. Period.

As a child our farm house burned down due to a gas leak to space heater as verified by a passing trucker who kicked in the front door to verify the house was unoccupied at the time. Decades later, my wife was 6 months pregnant with our 3rd child when we moved from a trailer house into base housing at NAS Meridian, MS. I used to sit in the evenings watching tv and see outlets in the trailer sparking. The next day, I would tighten the connectors on that outlet. Approximately 2 months after we moved into base housing, that trailer burned to the ground as a result of an electrical fire. Luckily the new occupants escaped unharmed minus their belongings. I don't do my own gas work and I don't do aluminum electrical.

[John K Jordan]

Not to hijack this thread, I've enjoyed reading the back-and-forth. I'm building a new second shop in the TX Hill Country, and will have a 100-amp service in it, about 100' from the incoming power pole. I plan on pulling three #3 conductors and a #6 ground -- all copper, in a buried conduit. ...

Something else to consider. I ran a smaller conduit with two cables of ethernet cable rated for underground. This let me put ethernet and wifi in the shop.

I also buried an extra 2" conduit in from the house to the shop with just a rope inside. I thought this might come in handy some day when I thought "if I had only ..."

JKJ

[John K Jordan]

...
I can't think of a good reason why an aluminum conductor would fail quicker underground than a copper conductor would. ...

When my long underground feed failed the general consensus from the professionals I consulted was the insulation may have had a defect, perhaps from manufacturing. I buried it directly from the big reel to the trench so I don't think I damaged it during installation. Apparently a tiny crack in the insulation can cause the aluminum to corrode to powder.

Another odd thing - when tracing the wire I found it had failed in several places and on multiple conductors. This makes me think even more that it may have been a manufacturing defect.

I never dug it up to examine it - it was easier for me to just dig a new trench and put in a new line, as I mentioned, copper in conduit this time, took me only a couple of days of work. And my Lovely Bride paid for the materials from her slush fund - she didn't like the idea of the security gate failing to open for her one day! (another 400' from the end of the long run)

450788 450789

JKJ

[Frank Pratt]

The aluminum vs copper debate pops up with some regularity with lots of valid points being brought up. I'll just add that among pros in the electrical industry (who have a large data set to work with), from engineers down to the lowly electrician, you'll find very, very few that are anti-aluminum for use in feeder conductors. The fact is that if installed correctly, copper and aluminum are both safe and reliable.

If you, personally, are more comfortable with going with copper over aluminum, that is perfectly valid. Just realize that doing so diverts funds away from other things and you are spending that money on peace of mind, not a better installation.

[Alex Zeller]

Directly buried wires with damaged insulation will result in both aluminum and copper failing. Things like galvanic corrosion will occur. Earth is a big giant ground with moisture in it.

[Rollie Meyers]

The NEC has no prohibition of Aluminum Alloy conductors, which is what all AL conductors have been since the early 1970's, and a improperly terminated copper conductor will cause the same issues that a improperly terminated AL alloy conductor will have. If anyone still made 10 & 12 AWG AL NM cable "Romex®" the NEC has no prohibition of it's use, but the only 10 & 12 AWG AL still around is new old stock NM cable & since it is not rated for 90° C like NM-B it is prohibited to be used, but even when Romex® was in the mid $100 + range, no one brought any 10 & 12 AL to market. :D