Aluminum 240v wiring

[PT Doc]

So my single car garage workshop area was wired by the builder's electrical group in 2015. This wiring runs through the ceiling of the unfinished basement enroute to this attached garage. I hard wired my compressor and all works well but I was surprised that the 240v wiring was not copper. There are qty 4 240v circuits in this garage current. 3 of the circuits use the same wiring and 1 is a different brand.

The writing on the sheathing of the 3 similar wires is below:

PRIORITY WIRE 3C 6awg (13.3mm2) 1C AWG (13.3mm2) AL AA-8000 Type SE STYLE R XHHW-2 XLPE 600v SUN RES (UL) E302630 2014 03764ft XQ

The sheathing on the other brand that was used:

ENCORE WIRE CORP TYPE SE STYLE R THHN or THWN CDRS 600V 3 CDRS AWG AA-8000 AL (UL) 23/MAR/15 10:22 3933 3817 4711

When I hard wired the compressor, I used appropriate size wire nuts and connected this wiring in the 2 gang box to the 10g THHN wiring and ran this to a compressor mounted disconnect switch and then from this disconnect to the pressure switch.

My question is regarding the aluminum/copper connection in the junction box. Is the wire nut appropriate for this connection and do I need to use some type of Naolox or anti seize pasted?

Thanks in advance for the help.

 

[pattenp]

Do not use regular wirenuts to connect aluminum to copper. There are wirenuts marked AL/CU but my feeling is they are used for either copper to copper or aluminum to aluminum, but not aluminum to copper. Those AL/CU wirenuts have been known to fail with aluminum to copper. You need to use something like this... https://www.homedepot.com/p/AlumiCo...gclsrc=aw.ds&dclid=CM6d4oHs_9cCFS-wswodJFoFng

 

[PT Doc]

I saw those after posting. Will need to find the proper size for #6 to #10 wire.

 

[JunkBonds]

I understand the aluminum copper thing but at the same time I don't uderstand it.

When you install copper into the panel it connects at an aluminum connection. This is allowed but seems to contradict the al/cu thing.

 

[PT Doc]

I can't seem to find a connector that would connect 6 gauge wiring. I understand the aluminum wire to an outlet issue with different expansion rates of copper and aluminum. I would think a wire nut with antiseize that had wires that were twisted well and then cut then inserted into nut would not be an issue but I'm not sure. Hopefully something is available for 6 g wire.

 

[OH_Varmntr]

I understand the aluminum copper thing but at the same time I don't uderstand it.

When you install copper into the panel it connects at an aluminum connection. This is allowed but seems to contradict the al/cu thing.

I believe it has to do with the type of connection used. Twisted connections apply different, less reliable forces to the materials than set screws do when it comes to expansion/contraction of the different metals.

 

[matt_i]

I understand the aluminum copper thing but at the same time I don't uderstand it.

When you install copper into the panel it connects at an aluminum connection. This is allowed but seems to contradict the al/cu thing.

I used to think that too but now my opinion is that the aluminum parts in direct contact have a tin-ish coating or plating that's non-reactive to the copper but of course "wets" the aluminum with full coverage. Sort of an electrically conductive buffer layer.

 

[pattenp]

I understand the aluminum copper thing but at the same time I don't uderstand it.

When you install copper into the panel it connects at an aluminum connection. This is allowed but seems to contradict the al/cu thing.

Lugs in a panel are not straight aluminum. They are an alloy that is rated for copper or aluminum wire connections. The issue is copper and aluminum wire will react with each other causing corrosion where the two different metals contact each other. Anti-oxidation paste prevents the oxidation of aluminum from air exposure. The surefire way to prevent any corrosion issues is not have aluminum and copper wire to come in contact with each other. There are split bolts rated AL/CU that have a divider that separates the two different wires to keep them from touching.

 

[rlitman]

I understand the aluminum copper thing but at the same time I don't uderstand it.

When you install copper into the panel it connects at an aluminum connection. This is allowed but seems to contradict the al/cu thing.

Not really. The aluminum lug on the panel uses an aluminum setscrew (if you replaced the set screw with a steel one, you'd guarantee a failure). Just like the Polaris style connector linked above that's AL/CU rated. The fact that the setscrew is made from the same material as the lug, guarantees that the screw will not back out through the expansion and contraction of thermal cycling.

Wire nuts use a steel spring. Thermal cycling eventually causes these to loosen on aluminum wires, which leads to failure.

What's happening, is that aluminum expands faster with increased temperature than copper or steel. The faster expansion of aluminum (the softer material) constrained by steel, causes the aluminum to become deformed (crushed). As the materials cool, the aluminum shrinks faster, and now the connection is just a little bit looser.

Now reverse this situation, with copper wiring in an aluminum lug. When heated, the aluminum will expand faster than the copper, which loosens the connection (however, the nearly imperceptible amount of loosening from just one thermal cycle isn't enough to be an issue). As the connection cools, it returns to it's original tightness.

I used to think that too but now my opinion is that the aluminum parts in direct contact have a tin-ish coating or plating that's non-reactive to the copper but of course "wets" the aluminum with full coverage. Sort of an electrically conductive buffer layer.

I don't believe they're plated. But they do use a special alloy designed for electrical connections. However, the issue with aluminum wiring is quite different from the issue with aluminum connections.

This page has a pretty good explanation of the issues with aluminum wiring:
http://www.southwire.com/commercial/AluminumBuildingWireHistory.htm

 

[theoldwizard1]

Polaris IT or ITO splice blocks are rated for copper and/or aluminum. Available in many sizes.

There is also a special aluminum wire anti-corrosion grease/gel that does what it says it does. I don't remember the exact name.

 

[brewchief]

A cheap 60 amp unfused disconnect can be a cost effective way to transition wire type/size.

 

[PT Doc]

Since today is Sunday and the local electrical supply house is closed, I was digging around At Home Depot. These are rated for aluminum and copper and have a block on the interior so that the 2 conductors do not touch.

https://www.homedepot.com/p/RACO-14-2-Dual-Rated-Splicer-Reducer-10-Pack-of-2-AMS2BAG2R/202944409

Another option on the HD site that I did not see at the store:

https://www.homedepot.com/p/Blackbu...lid-Barrier-Wire-Stop-ASR2506-B1-10/100190266

My question is if I connect the 4 wire pairs with these, would it be ok to use 1000v shrink tubing to cover each splicer? The splicer are UL listed and the 1000v shrink is UL listed.

https://www.homedepot.com/p/Gardner...l-Heat-Shrink-Tubing-Black-HWT-0025/205881703

Adding this to the aluminum wire end:

https://www.homedepot.com/p/Ideal-NOALOX-4-oz-Anti-Oxidant-Compound-30-026/202276208

Or would covering the aluminum wire with an anti seize like this would be a good idea?

http://na.henkel-adhesives.com/product-search-1554.htm?nodeid=8797898047489

Hoping that this work.Thanks

 

[Bert_]

The polaris connectors are nice since they are already insulated. Split bolts work just as well but you have to wrap them in tape.

I will second the idea of using a disconnect. A 60A A/C disconnect would work well and they are cheap, like $15. Sounds like the breaker is in another room so it should have a disconnect anyway.

 

[rlitman]

Since today is Sunday and the local electrical supply house is closed, I was digging around At Home Depot. These are rated for aluminum and copper and have a block on the interior so that the 2 conductors do not touch.

https://www.homedepot.com/p/RACO-14-2-Dual-Rated-Splicer-Reducer-10-Pack-of-2-AMS2BAG2R/202944409

Another option on the HD site that I did not see at the store:

https://www.homedepot.com/p/Blackbu...lid-Barrier-Wire-Stop-ASR2506-B1-10/100190266

My question is if I connect the 4 wire pairs with these, would it be ok to use 1000v shrink tubing to cover each splicer? The splicer are UL listed and the 1000v shrink is UL listed.

https://www.homedepot.com/p/Gardner...l-Heat-Shrink-Tubing-Black-HWT-0025/205881703

Adding this to the aluminum wire end:

https://www.homedepot.com/p/Ideal-NOALOX-4-oz-Anti-Oxidant-Compound-30-026/202276208

Or would covering the aluminum wire with an anti seize like this would be a good idea?

http://na.henkel-adhesives.com/product-search-1554.htm?nodeid=8797898047489

Hoping that this work.Thanks

It is absolutely imperative that you do not use a conductive grease! So any metallic anti-seize is out of the question. That stuff will get everywhere, and leave everything it touches conductive. That's a really bad thing on an electrical connection.

I guess that heat shrink would be ok. I'd probably opt to protect it with a wrap of friction tape on top.

Noalox is appropriate for dry connections, but any grease (i.e. contamination) would interfere with heat shrink getting a watertight seal (if this were to be used underground). The first Polaris style insulated connections linked above came with a noalox like compound already inside. If you were to buy dry Polaris connectors, then adding noalox would be a good idea if you're using them with aluminum wiring.

 

[PT Doc]

The initial circuit is is run with 6/3 aluminum wire. I have run all 4 wires to my compressor mounted leviton motor rated disconnect in a Leviton enclosure. This motor disconnect is rated for 10 hp @ 240v. It's a leviton MS602 disconnect.

If the easiest way to connect these 6g aluminum wires to the 10g copper wires is using a wall mounted safety switch, then it should be a quick install that is up to code and not a cobbled up solution.

I found this GE safety switch:

https://www.homedepot.com/p/GE-60-A...r-General-Duty-Safety-Switch-TG4322/202978657

This is a 3 phase indoor safety switch. My circuit is a typical 240v single phase residential circuit. Since I want to connect all 4 of the aluminum wires to the copper wires, this 3 phase switch should work. Specs on the wires show that it is good for 12-2 AWG wires in both copper and aluminum. Seems like this should sort me out.

I could call GE tomorrow to verify that this will be an appropriate solution.

 

[Norcal]

The polaris connectors are nice since they are already insulated. Split bolts work just as well but you have to wrap them in tape.

I will second the idea of using a disconnect. A 60A A/C disconnect would work well and they are cheap, like $15. Sounds like the breaker is in another room so it should have a disconnect anyway.

Home Depot has a Halex disco for around $5, proper connector will cost more than that.

 

[PT Doc]

Thanks for all the help!

I called the county electrical inspector. I asked if the splicer/reducer covered in 1000v electrical shrink tubing would be ok. He said it would. He also said I could wrap the reducer blocks in rubber electrical tape then wrap in vinyl tape. The tape on the rolls will be more difficult to wrap with because of the wire size and 4 strands in a 2 gang box. The shrink tubing is a 4:1 shrink so there should be no issue getting a tight fit.

Simple and easy solution and all available from Home Depot. And to code.

 

[PT Doc]

Polaris IT or ITO splice blocks are rated for copper and/or aluminum. Available in many sizes.

There is also a special aluminum wire anti-corrosion grease/gel that does what it says it does. I don't remember the exact name.

I looked into the Polaris connectors and the IT-4 connector from the Polaris brand is the right connector for my situation. It is interesting that electrical supply houses have a variety of brands like Ilsco and Bernby that have a corresponding part. The Ilsco PBTS-2-4 is a zinc plated connector with a thermoplastic outer housing . Set screws were 1/4" hex and for the #6 wire the torques spec was 35 in lb and the #10 wire was 20 in lb. I'm glad I bought a harbor freight 1/4" torque wrench some years ago. The hex screws live in a tunnel 90 degrees to the wires and have insulation caps. The four connectors fit in the 3.5x3.5x4" box with the 6/3 wire and the 4 strands of 10 wire.

https://commerce.ilsco.com/e2wShopp...k=2100001183:3100012208:3100012209:3100012698

https://commerce.ilsco.com/documents/PDF/TechnicalDrawing/M2843.pdf

This was the simplest solution since I already have a moot rated disconnect shutoff on the compressor and I already ran the liquidtite from the compressor to the wall plate for this junction box.

While an ac disconnect or a safety switch could have been mounted on the wall, the Polaris type connectors worked great. At $11 each it worked out well. I linked to some splicer reducers in an above post but they need to be covered in rubber tape and then vinyl tape that that was going to be awkward to do so in this size box. And supposedly the rubber tape bonds to itself so if I needed to undo the wiring for some reason, it would be messier.

Again, thanks to all for the help. I greatly appreciate the expertise on this forum and willingness to share your knowledge and experience.