Question joining #8 Al to #10 Cu wiring

[DLausche]

I've got a question for you Electricians out there.



I am working on a shop addition. The only circuit I can use to supply power to the new shop is the old electric dryer circuit. We've had a gas dryer for years now so this circuit is not used anymore. It is a 220v, 30A, 2 phase circuit. Not a lot of juice, but will suffice for my simple shop needs. Anyways, this dryer circuit was wired with #8 Al wiring when house was built 10 yrs ago. I am removing the dryer outlet and will be extending the circuit out to the new shop with 10-3 Cu wiring. What method do I need to use when connecting the Al and Cu wiring together. I know I need a junction box. Will a simple 4x4 metal box suffice? I've got some anti-oxidant joint compound (NOALOX) that indicates it is good for Al-Cu connections. Do I use this and then just a simple wire nut on the connection or do I need a box with 4 separate screw-down lug connections? The junction point will be in the laundry/utility room downstairs and will never have a finished ceiling so I was planning on locating the junction box on one of the upstairs floor joists.



I guess I am paranoid about the Al wiring because I've heard stories of fires, etc. I've done a fair amount of wiring in my days and am comfortable doing most anything myself. I've never worked with the Al stuff so want to be on the safe side here.



Thanks much.

-Deon

 

[xpetecx]

I've got a question for you Electricians out there.



I am working on a shop addition. The only circuit I can use to supply power to the new shop is the old electric dryer circuit. We've had a gas dryer for years now so this circuit is not used anymore. It is a 220v, 30A, 2 phase circuit. Not a lot of juice, but will suffice for my simple shop needs. Anyways, this dryer circuit was wired with #8 Al wiring when house was built 10 yrs ago. I am removing the dryer outlet and will be extending the circuit out to the new shop with 10-3 Cu wiring. What method do I need to use when connecting the Al and Cu wiring together. I know I need a junction box. Will a simple 4x4 metal box suffice? I've got some anti-oxidant joint compound (NOALOX) that indicates it is good for Al-Cu connections. Do I use this and then just a simple wire nut on the connection or do I need a box with 4 separate screw-down lug connections? The junction point will be in the laundry/utility room downstairs and will never have a finished ceiling so I was planning on locating the junction box on one of the upstairs floor joists.



I guess I am paranoid about the Al wiring because I've heard stories of fires, etc. I've done a fair amount of wiring in my days and am comfortable doing most anything myself. I've never worked with the Al stuff so want to be on the safe side here.



Thanks much.

-Deon

Sounds to me like you know what your doing well enough to do it. I would use the noalox for sure it will keep the connections from corroding. as far as wire nuts or terminals. I quess you would have to see if the wirenuts are rated for the aluminum copper connection. Off the topp of my head I dont know. As far as a Box goes get a 4 11/16. Not sure if you need it but it will make it a little easyer to terminate.

 

[Headshot zod]

To the best of my knowledge aluminum can only be used from the pole to your panel. It is no longer allowed to be used in branch circuits. Since yours is already installed it is grandfathered in. But that doesn't make it safe. The reason it isn't used is because it gets brittle and falls apart and may lead to a fire.



Run a new line... ... .....

 

[C. Harlan]

On House services at work, we use Linkets, and press them on. . Not sure where you could find those, but I know they would work wonders. . Check some of your electrical supply stores around your area... Sorry I couldn't help you more!



-Chris-

 

[Dieselnut59]

I have heard the same story about aluminum. I have a 100amp "sub service" run from my house to my barn that is direct bury aluminum wire. It is what is used to supply the power to mobile homes. It is a solid run from 100 amp breaker to 100 amp breaker (with the noalox on the terminals). I would be scared about the additional junction in your house. Cut off the 30 amp breaker and loosen the cable clamp that retains the wire and see if you can pull the wire from your basement. If you can, you will SURE be better off running all new copper. You can run quite a lot of equipment/lights/etc on a 240v 30 amp circuit.

 

[DLausche]

Believe me, I would do just about anything (within $ reason) to get rid of this Al wiring. House is a split entry with main panel in corner basement furthest from addition. 2x10 floor joists. #8 Al wire is run through 3/4" hole through about 20 joists then around 90* corner and straight for 25' or so to panel. Ceiling is finished sheetrock. I'd have to rip out majority of the ceiling to fish a new wire through and I think I'd have to move out if I tried that route...



I checked my wire nuts and they clearly state "copper to copper only". I will look tomorrow to see if I can find any wirenuts rated for Al wiring. Maybe the kind that have a tap screw in them to tighten down instead of just twisting on. I'll check out Linkets as well and see if I can find out more about them.



Thanks for the info guys.

-Deon

 

[Dieselnut59]

I only have a 150 amp service to my house and it is supplied by aluminum. I added the 100 amp service to the barn, but deleted lots of electrical load doing what you did, by going to gas appliances. My house had an electric water heater, clothes dryer, range and room a/c unit on the 240 circuits. I went with all gas (propane) appliances and a dual fuel (heat pump/propane) HVAC system. Only things I have that require 240V are my dual fuel HVAC compressor and my well pump, in addition to my overkill panel in the barn. Another bad thing I have heard about aluminum is it gets weak everywhere you bend it and the more you have bent it, the weaker it has gotten, thus the more heat it can build up at the weak spots. Resistance is a bad issue with aluminum too and it develops a lot of heat quickly at points of resistance.

 

[rbattelle]

To the best of my knowledge aluminum can only be used from the pole to your panel. It is no longer allowed to be used in branch circuits.

It seems to me that the primary problem with aluminum wire use in branch circuits only applies to conditions where a wire nut junction will be in use. So in going from the main box circuit breaker to a sub panel circuit breaker (branch line) would be perfectly acceptable and safe, since no wire nuts are required (use NOALOX, of course, at the terminations). Then from the sub-panel you run copper wire to the outlets where wire nuts will be used.



This site is interesting.



Ryan

 

[gregdoerfler]

OK I am an electrician in PA and there is nothing here that says it is against code to run aluminum wire to branch circuits just have to use nolox on the wire. they do make wirenuts that are rated for cu and al. go with a 4 11/16 box like mentioned and get split bolts rated for cu to al it would be a much better splice there is a bar that goes between them to seperate the wires but be sure to tape them up good.

 

[Dl5treez]

You didn't go into a lot of detail on what you want for service in your shop.



Do you want 110v/220v or just 220v?



Is the existing dryer a 4 wire (2 hots, 1 neutral, 1 ground) or 3 wire (2 hots, 1 ground) circuit?



I'll assume @ 10 years old it is 3 wire 220v which is fine if you just want 220v service in your shop and no 110v.



If you want 110/220 then I'd suggest you run a 6/3 plus ground copper romex, change the breaker out to a 60 amp and set a sub panel in the shop where you can then add both 110v and 220v circuits. The copper can be spliced onto the aluminum--generally we use crimp on butt splices rated for CU/AL with Noalox. You can also use a mechanical set screw butt splice.



With either splice method, wrap the splices with 1 layer of 3m 33, then rubber tape (2 layers) then 2 layers of 33. Use a 4 11/16 box or larger for the joints. If you use a metal box, remember it has to be grounded.

 

[DLausche]

The service in the shop will be 110 and 220. The #8 Al wiring is 2 hot, 1 neutral, and 1 ground so I should be ok running 220 and 110 off of it. I put a 60A subpanel with 6 breaker positions in the new shop. 4 of them are 110 branch circuits and the other is a 220 circuit for a small 220 welder if I ever need one.



I'll check out the local supply house for some split bolts rated for Al and Cu. This sounds like it would be a very secure way of connecting them together.



Another idea I had is to use an AC style disconnect that is rated for Al wiring connections. I've got one in my parts bin. It's a 60A non-fusible pullout disconnect with blade style contacts. Only issue is that it is rated 240v, 1 phase only. Would be easy to hook up 2 phase 220v though if I just swapped out the 2 screw ground bar with one that has 4 set screws. Not sure though if it is legit to bond the neutral and ground together mid way on a branch circuit. The inspector probably wouldn't like it either because it will still say 240v, 1 phase even if I do swap in the correct ground/neutral bar connection.



Thanks for the info guys. Off to Menards I go for some split bolts...



-Deon

 

[xpetecx]

Yeah dont bond the neutral and ground. the only place that is allowed is at the main panel.



I talked to some guys at work today and they said use the terminal strip or split bolts to do in not the wire nut.

 

[rbattelle]

What is 2-phase 220? Are the phases separated by 120* or 180*? My house only has single-phase 240 service.



Ryan

 

[Dl5treez]

I'll check out the local supply house for some split bolts rated for Al and Cu. This sounds like it would be a very secure way of connecting them together.

Split bolts and mechanical set screw splices aren't the same, and split bolts used to not be approved for permanent usage--they were only for temp use. The code in your area may be different, but IMHO I'd shy away from split bolts.

Only issue is that it is rated 240v, 1 phase only. Would be easy to hook up 2 phase 220v though if I just swapped out the 2 screw ground bar with one that has 4 set screws.

You don't have two phase 220v, you have split phase, or three-wire single phase. I don't think it should be a problem.

 

[Dl5treez]

What is 2-phase 220? Are the phases separated by 120* or 180*? My house only has single-phase 240 service.



Ryan

Ryan, true two phase power hasn't been in use since the early 20th century. They were two separate power circuits with voltages 90 degrees apart in time. Back in the day, this was an easy way to deal with unbalanced loads, and allowed for simpler self-starting motors. With technology came the knowledge of how three phase power could work, and two phase was relegated to the past, where it belongs. Two phase is still present is some control systems, but is rare.



Many people, even in the industry, confuse 120v/240v three wire single phase as two phase power, but it isn't.



Sorry for the hijack.

 

[rbattelle]

Ryan, true two phase power hasn't been in use since the early 20th century. They were two separate power circuits with voltages 90 degrees apart in time. Back in the day, this was an easy way to deal with unbalanced loads, and allowed for simpler self-starting motors. With technology came the knowledge of how three phase power could work, and two phase was relegated to the past, where it belongs. Two phase is still present is some control systems, but is rare.



Many people, even in the industry, confuse 120v/240v three wire single phase as two phase power, but it isn't.



Sorry for the hijack.

Ah ha! I was starting to think I was missing an entire class of electrical power system.



Ryan

 

[DLausche]

Yeah dont bond the neutral and ground. the only place that is allowed is at the main panel.

Yeah, instinct was telling me that this wasn't the right thing to do.



Didn't have any luck finding Al/Cu rated split bolts in the proper size. Those that were rated for Al were for a LOT larger wire than I'm working with here. I did end up finding some Al/Cu rated "splicer/reducer" connectors that secure the wire with a set screw. Has one set screw for each wire with a separator in the middle so the different metals do not touch each other. Will also use plenty of noalox on the connections. They are non-insulated so I'll have to tape them up really well.



-Deon

 

[DLausche]

Ryan, true two phase power hasn't been in use since the early 20th century. They were two separate power circuits with voltages 90 degrees apart in time. Back in the day, this was an easy way to deal with unbalanced loads, and allowed for simpler self-starting motors. With technology came the knowledge of how three phase power could work, and two phase was relegated to the past, where it belongs. Two phase is still present is some control systems, but is rare.



Many people, even in the industry, confuse 120v/240v three wire single phase as two phase power, but it isn't.



Sorry for the hijack.

Thanks for the info. Learned something here today. The way I understand it is the 240 is single phase and the 2 120 sides are 180* out of phase with each other. Right? I always thought that was called 2 phase - from the 120v point of view. So, then I should be able to use the 240v, single phase disconnect panel? Not sure how that would/should work without bonding the neutral and ground together on the single ground bar. I am really leaning towards not going that route and using the connectors in the previous post but I am curious now how one would properly wire a 3+1 240 line in a disconnect box that has only 2 hot connections and one ground bar.



-Deon

 

[gregdoerfler]

the panel box you get should have one bar isolated from the frame on the panel this would be your neutral then you need to get a seperate ground bar and screw it to the frame of the panel. that conector that you got looks like it will work.

 

[DLausche]

Let me start here by giving everyone a big thank you for the help and tips provided. I passed my electrical inspection. I did have one thing wrong and that was to install an 8' ground rod and bonded it to the ground in the secondary/new distribution panel in the new garage. I guess only one ground rod is allowed. I was certain that two ground rods would offer more protection that just one. Oh well, easy enough to remove the ground wire. Thanks everyone.



-Deon