splicing aluminum to copper elec wire

[12th_Man_Fan]

I just bought a new oven and it came with aluminum wire and I have to splice it to copper. Do I need to do something different for this connection?

I know aluminum and copper doesn't play well together in some instances.

Thanks in advance for the you help.

[MEXICOWANDERER]

The two conductors can not touch each other. And tin plating is just that. Plating, not cladding. One scraping or heavy-duty wire brushing and it's back to bare aluminum. Confirm this yourself by trying to solder what you believe to be tin coating.

I watched a 27 KV corona eat a junction, clamp and three feet of transmission conductor. It is humbling even though I had nothing to do with it.

I had a good HP thermographic 4" imager then it died and HP told me there were no fixes. I sure miss it 😞

[Gdetrailer]

Mex,

The simple thing is to verify the interface is OK to use with AL..

Pretty much every electrical connection item out there now days IS marked with CU or CU/AL or AL as to what type of wire can be connected.

If device is not marked, one should assume it is CU only..

Just looked through some of my extra electrical stuff, receptacles and switches are marked CU/AL.. Bunch of breakers I have are all marked CU/AL..

The only dissenter in the group is an extra welder 50A 240V plug, it is marked CU..

With any AL wire, the use of NOALOX or OXGard is highly recommended at the terminations regardless (my local electric co inspector will not pass any service entrance connections with AL wire if you did not use NoAlox or OXGard). It helps to keep the moisture away from the wire and connection.

I have found that NoAlox and OxGard can also be very helpful for ANY wire connection that is outdoors, works wonders for even old school POTS network interface box connections for wire phones and DSL.

[BurbMan]

Ah OK...a wall oven or a cooktop are both hard-wired with pigtails. I was thinking a free-standing electric stove...those come with terminals so you can attach a cord.

[time2roll]

BurbMan wrote:

time2roll wrote:
I just put one in two years ago and the Kitchenaid electric oven most definitely came with an armored pigtail to be hardwired. No instructions to replace with a cord and plug.

No kidding? I stand corrected then. Hard to believe then that they would include an aluminum wire, it must be tinned copper.

Yes and same thing on the microwave. 240v armored pigtail. Yes both that I did had stranded copper wire.

[MEXICOWANDERER]

If you connect unplated aluminum to the BRASS terminals of a standard 50 amp oven plug you are setting yourself up for a surefire FIRE. Show me a non-marine appliance plug and you will be showing me a solid BRASS conductor plug.

Aluminum to brass is even worse than aluminum to copper. The high percentage of zinc of the brass is even less noble than copper. Not theory, been there seen fires and shook my head.

Thick thick tin or gold plating on a BUTT TYPE CONNECTOR is the only way to handle AL/CU joints. I made a box of KERNEY NUTS in the late seventies and used adjustable DIES to undercut the threads so that they could be GOLD CLAD which is far thicker than gold plate. Oakland Plating demanded payment in advance and I paid thirty-five dollars EACH to have the connectors gold clad. This is when gold plating was a thirtieth the price it is currently.

Aluminum wire is a thousand times (exaggeration) more brittle than copper wire especially rope stranded premium welding or DSO cable.

Bend AL wire back and forth a half dozen times and it will snap in two. I use it. But I do not fail to clamp it, strain relieve it an inch from the termination then bundle the wire tightly to other wires throughout its length. It is all copper plated which I solder and seal tightly on both ends then seal it with adhesive heat shrink. THEN glob silicone grease or 3M sealant over the joint.

The conductors for a service drop are AL. But they are wound around a solid galvanized steel wire rope which serves as neutral. The conductors inside a service drop box, meter mounting, and breaker box are thick tin plated conductors.

This serves to show why if you encounter a badly overheated connector inside your RV do not clean the wire bores. Replace the assembly. Once the tin has been burned and scraped away you are left with a direct AL/CU contact and COSMOLINE better hyped as NAALOX only serves to buffer for so long. Then it's smolder and fire time.

Truly superior tension binding devices are simply not available for residential or even commercial use. But I shall describe them here just for your edification.

When I ran 13 miles of 37 KV overhead wire down here I had to join AL/CU. Without a bucket and hydraulic crimper I used very strong plated springs beneath the bolts and nuts. Constant tension devices that would maintain the same PSI whether conductor temperature was Oc or 100c. You can see yourself the effect of temperature and tension inside your own breaker box when you retighten screws every few years even though you haven't moved your rig.

RAMP LOC washers stay tighter than USA grade shakeproof star washers which in turn are far more secure than split washers. Distorted threads have excellent retention except after several uses.

In a nutshell there it is, sixty years of hard-earned experience.

[Gdetrailer]

12th Man Fan wrote:

frankwp wrote:
Are you sure it's aluminum? That would be highly unusual. It's probably tin plated copper.

Thanks everyone for your input. I am kind of anal when it come to stuff like this.

I looked at the wire closely and it sure looks like aluminum but on the wire I found AWM style 3321 which is tin plated copper so I don't have the problem I thought I had.

The oven is at my home and it is a built in oven. There is a very heavy three conductor wire sticking out of the wall and that is how the old oven has been hooked up for 35 years so I guess going back the same way will be OK now that I know it is not aluminum.

Thanks everyone for taking the time to respond. There is a wealth of knowledge available on the site and you are willing to help. This is why I asked the question here.

The oven came wit an armored pigtail with 12 ga wire and it was not intended to be changed.

Thanks again

Yup, really doubted that any manufacturer would use aluminum wire for that short run. Would be highly unusual to find that since most manufacturers are well aware of the potential issues with interfacing copper with aluminum..

The receptacle/plug method for a built in oven can be a nice upgrade, learned that trick from my Dad. He built his house in the 1950s and was way ahead of his time by putting a plug in receptacles for his built in oven and even separate stove top. Makes it extremely easy if the need arises for servicing or removing them for any reason.

I believe it is code now days to include a servicing switch for the receptacle.. But your option, just trying to make it a bit easier for you down the road.

[12th_Man_Fan]

frankwp wrote:
Are you sure it's aluminum? That would be highly unusual. It's probably tin plated copper.

Thanks everyone for your input. I am kind of anal when it come to stuff like this.

I looked at the wire closely and it sure looks like aluminum but on the wire I found AWM style 3321 which is tin plated copper so I don't have the problem I thought I had.

The oven is at my home and it is a built in oven. There is a very heavy three conductor wire sticking out of the wall and that is how the old oven has been hooked up for 35 years so I guess going back the same way will be OK now that I know it is not aluminum.

Thanks everyone for taking the time to respond. There is a wealth of knowledge available on the site and you are willing to help. This is why I asked the question here.

The oven came wit an armored pigtail with 12 ga wire and it was not intended to be changed.

Thanks again

[BurbMan]

time2roll wrote:
I just put one in two years ago and the Kitchenaid electric oven most definitely came with an armored pigtail to be hardwired. No instructions to replace with a cord and plug.

No kidding? I stand corrected then. Hard to believe then that they would include an aluminum wire, it must be tinned copper.

[Cummins12V98]

Hondavalk wrote:
https://www.lowes.com/pd/Alumiconn-3-Port-Al-Cu-2-Pack-Purple-Al-Cu-Wire-Connectors/4433877#:~:text=...

That product is designed for #10-12 Aluminum. I am sure they make a connector like that to fit the larger gauge wire on an oven. A very good solution.


Personally I would prefer the cord/receptacle method shown above.

[time2roll]

BurbMan wrote:
Electric stoves don't come with wire, they come with a terminal block that you connect your wire to.

Op said Oven not stove if that matters.

I just put one in two years ago and the Kitchenaid electric oven most definitely came with an armored pigtail to be hardwired. No instructions to replace with a cord and plug.

[Hondavalk]

https://www.lowes.com/pd/Alumiconn-3-Port-Al-Cu-2-Pack-Purple-Al-Cu-Wire-Connectors/4433877#:~:text=...

[ppine]

Thanks to Old Biscuit and Mexico.
do it right.

[BurbMan]

Electric stoves don't come with wire, they come with a terminal block that you connect your wire to. I suspect that the home has an aluminum wire going to the stove, since many houses built in the early 70's used aluminum for heavy gauge feeds like stove, dryer, and a/c. The terminal block on the new stove is probably labeled "Copper wire only."

The best way to wire this new stove is to terminate the aluminum wire coming out of the wall into a receptacle box that is Cu/Al compatible like this one at Lowe's.



Then get yourself a copper cord set like this to attach to the stove and plug in to the new receptacle.



This is the safest way to do this without replacing the wire, since you can't safely connect the aluminum wire directly to the range.

[frankwp]

Are you sure it's aluminum? That would be highly unusual. It's probably tin plated copper.

[rhagfo]

Well the OP has not replied to any post yet, just posted last night so give him some time. I recall installing an oven in the kitchen of our house about 20 years ago. It was CU to AL connection, sing an oven and on a 40 amp circuit I think the wire sizes were #8 and #6, I used the CU/AL goop and split bolts. The connection was then wrapped rubber insulation tape followed by electrical tape. The connection was made in a large J-box with an extension (4-11/16” box) and cover in the cabinet below the ovens. Never an issue! I would never use twist on connectors on the size wire.