I am replacing my old electric range which is hard wired with a 3-wire circuit. (The installation instructions for the new range permit this -- 3-wire is OK and a power cord is not required.)

I assumed that this would be pretty straightforward to do -- disconnect the wires from the old range and reconnect them to the new one. But when I looked at the wires, I was surprised to see that they're not copper, although there is copper wiring elsewhere in the house.

The 3 multi-gauge wires are bundled in a grey sheath coming out of the wall. Where the 3 individual wires connect to the range, the hot wires are sheathed in black insulation; the neutral wire is bare. The wires are silver colored. The stripped ends have black "grease" on them where they are attached to the range.

Can I proceed as planned, and simply hook these wires to the new range?

 

I would not. I would replace the cable with a new four wire copper cable, NM-B 6-3.

 

> I was surprised to see that they're not copper

The wires are aluminum, which is very common for range circuits. The grease is there to prevent oxidization of the metal, which is very important for aluminum wire. When re-installing the aluminum it's a good idea to shine up the wire with a wish brush or emory paper and re-apply some NoAlOx grease before torquing down the screw terminals.

> Can I proceed as planned, and simply hook these wires to the new range?

So long as you are not moving the existing circuit, you may re-use it for the new range. Personally I prefer to install a range receptacle, but you may also hardwire if the range permits.

Check the range installation manual and see if the screw terminals inside the range are rated for aluminum wire. They will be marked CO/ALR if they can handle aluminum.

If the range is not rated for aluminum, then you'll need to buy a three-wire range receptacle which is CO/ALR rated, and install a 3-wire cord & plug on the range as per the instruction manual.