tinned copper or aluminum?

Hello all. I recently bought a Suntouch radiant heat mat for a tile floor in a bath remodel. I checked everything out and found that the solid 14 gauge wires on the thermostat look like aluminum. I initially thought that they were tinned copper so I scraped them to make sure and I don't really see any copper color. I'm still waiting to hear back from the company. Anyone ever work with these? I can't really see a company in this day and age using aluminum wires. thanks

 

Aluminum winging is OK. But certain precautions must be taken. The weak link in AL is the connection points. You need a solid mechanical connection to prevent loosening of the contacts. On your main box you'll notice aluminum wiring is used from the utility pole. Many homes with AL wiring need to pig tail a copper wire with a wire nut then using the screw connection on the outlet.

 

I'm going to wait for the electrical experts to comment. But for safety's sake:

You are preventing oxidation, which occurs when two dissimilar metals are connected to one another. The oxidation will not allow for good contact and cause the wire to overheat. I have seen AL to CU connections made with a regular wire nut that have melted the wire nut. Not good.

I'll leave this to the electricians. Special AL receptacles and switches can be purchased. You can't pigtail AL to CU.
I understood you could use anti oxidation compound (with proper training), but that may have changed.

Aluminum wiring is touchy at best.

 

The only approved wire nut is considered unsafe by many. What's Wrong With Using Twist On Connectors For Aluminum Wire Repairs? - AlumiConn | Aluminum to Copper Electrical Connectors Not just a solid connection but physically isolate the copper from the aluminum. For a time manufacturers were allowed to remark copper receptacles as aluminum rated. That proved unacceptable over time. Source: COALR CO/ALR CU-AL or AL-CU marked Electrical Outlets and Switches with Aluminum Wire

 

Ray,
These outlets are still manufactured and sold:

Attachment 36497

For direct connection to aluminum wires: are these allowed??

•15 Amp/125-Volt Grounding
•Residential grade, NEMA 5-15R, 2P, 3W
•Straight blade; side wired; steel strap
•For use where aluminum wiring has been installed
•Terminal screws are made of special materials and designed to grip aluminum wire very tightly
•Self grounding
•Straight blade
•Side wired
•Ivory finish
•Ivory finish
•NEMA 5-15R, 2P and 3W

 

Try snipping an 1/8 to 1/4 inch off the end of a wire and look at the end, is there a copper core? If there is a copper core it is probably tinned copper wire. If no copper core, continue to contact the manufacturer.

You NEVER want to connect aluminum wire directly to copper wire with any wire nut. The copper and aluminum must be connected so they are not in direct contact, the AluminConn connector is one of the two best ways to do this. The Ideal purple #65 Twister connector is U.L. Listed for connecting copper to aluminum wiring, but it has an extremely high failure rate and was never intended for pigtailing applications. Originally these were listed for connecting a light fixture with copper wire to aluminum house wiring where the actual current draw was very low. The U.S. Consumer Product Safety Commission doesn't accept any type of twist on wire connecter for use with aluminum wire.

Aluminum wire starts to oxidize the instant the insulation is stripped from the wire and it comes into contact with the air. Those receptacle are approved for direct connection to aluminum wire IF they are marked CO/ALR. Older receptacles with markings of Cu/Al or Al/Cu were not designed for aluminum wire, those markings were applied to those older devices designed for copper wire to appease contractors many years before the industry fully understood that receptacles designed for copper wiring were not suitable for aluminum wiring. They are the same as devices that were used for copper wiring in that era. Even when using CO/ALR receptacles, the aluminum wire must be properly abraded and coated with antioxidant compound before being attached to the devices.

 

OK Casual,
I opened up a can of worms again..

Scenario: Hardwired dishwasher with household aluminum wiring.
How to wire???
It was my understanding you could properly abrade wires, apply nolox or oxgard, working compound into wire with emery cloth, then carefully fill regular wire nut with compound and connect as usual...........
Please advise,
Brian

 

This is getting away from the topic of the thread, but....I'll try to give some advice anyway. What can they do, take away my birthday?

You cannot use any regular wire nut, they aren't approved for use with aluminum wire. I would suggest adding a cord and plug to the dishwasher and installing a CO/ALR rated receptacle under the sinkbase cabinet and just plugging the dishwasher into it. This would also satisfy the requirement for a disconnect for the dishwasher. If you are direct wiring, the AlumiConn connectors should be used, but I don't believe they can be used with stranded wire so the dishwasher leads would need to have solid copper wire pigtails added to them before connecting to the AlumiConn connectors. The best way is the receptacle under the sinkbase.

 

No they need to be connected with connectors such as the AlumiConn Joe mentioned or Polaris or special split bolt connector all of which separate the aluminum from the copper. Antioxidant is still required.

 

A standard wire but is not listed for use with aluminum conductors whether filled with Penetrox or not. I would use a junction box with the Alumi-conn connectors to run a new copper tail or use a cord and install a receptacle.

 

Wheeeeew!! Two moderators and I still have my birthday!