- 1). Cut the stripped end of the conductors (wires) flush with the insulation. The exposed aluminum wire will have oxidation build up on it. You want to start with wire as oxidation free as possible because it is impossible to keep it totally oxidation free. The aluminum wire starts to oxidize as soon as it is exposed to air. Speed is of the essence when working with aluminum wire.
- 2). Avoid weakening the conductor and increasing its resistance by adjusting your wire stripper's depth of cut using a scrap piece of wire of the same gauge that you are splicing. The depth of cut should be such that the insulation cuts cleanly without the jaws biting into the wire itself. Aluminum wire is exceptionally soft and easily damaged. Ringing the wire, cutting a groove around it, will weaken the wire and cause it to break. Besides weakening the wire, ringing reduces the wire's cross-sectional area, which increase the resistance to current flowing through it.
- 3). Strip 3/4 inches of insulation from the ends of the conductors. Hold the stripped ends of the wires side by side. Twist the wires tightly together with the lineman's pliers using a right-hand twist. A solid electrical connection begins with a solid mechanical connection. Twisting them together as tightly as possible is especially important when joining copper to aluminum. Aluminum and copper expand and contract at vastly different rates, which gives the joints a tendency to loosen up with time.
- 4). Screw on a "Purple" wire nut to complete the splice. Screw the wire nut on finger tight and then give it another couple of turns with the lineman's pliers. Tightening the wire nut forces the antioxidant compound between the twisted wires. Tightening the wire nut securely over the splice is the key to making copper-to-aluminum splices that meet the National Electrical Code requirements.
- 5). Wrap the completed splice with several layers of black, plastic electrical tape. You are not required by the NEC to wrap the splice with tape, but it is an extra safety precaution taken by most electricians to keep the wire nut from working loose over time.
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