Cut off the transformer's electric source. If the transformer plugs into a wall receptacle, pull it from the outlet. If the transformer's high-voltage leads are hard-wired into a circuit breaker, turn off its circuit breaker.
Examine and determine the transformer's low-voltage wire connection type. Some transformer models connect to cable lights with terminal screws, some use terminal prongs and some have leads, which look like short wires.
Remove 1/4 inch of the insulation from the ends of both cable light wires with wire strippers.
Prepare the ends of the cable light wires. If the transformer connects to the low-voltage cable light wires with prongs, then slip the correct style wire connector onto the bare wires and tighten the wire connector against the wire with pliers. If the transformer uses terminal screws or leads, then leave the ends of the cable light wires bare.
Connect either cable light wire to one of the transformer's low-voltage connections. If the transformer uses prongs as its low-voltage connection, push the wire connector onto the prong. If the transformer has terminal screws, wrap the bare end of a cable light wire around a terminal screw and tighten the terminal screw with a flat-head screwdriver. If the transformer uses leads, twist a lead around a cable light wire and secure them together with a wire nut.
Attach the second cable light wire to the second transformer low-voltage connection using the same method as on the first cable light-to-transformer connection. Cable lights and transformers have interchangeable low-voltage wire connections.