Cut the boundary wire to remove the section that you want to cancel out. For instance, if you want to cancel the signal for a 5-foot section, measure the wire and cut a section 5-feet long from the current boundary wire.
Cut two pieces of boundary wire 2 feet longer than the opening. The reason you need extra wire is to account for twisting in the next step.
Hold the two wires together at one end. Have another person start twisting the two wires together so you will have 8 to 10 twists per foot.
Lay the wire where you cut out the section of boundary wire. If the wire is a little too long, use the wire cutter to remove each of the ends of the wire so that the boundary wire and the twisted wires can be easily connected together.
Strip 1/2 inch of insulation off each of the wires on the twisted wire and the two ends of the boundary wire. Insert the twist wire and boundary wires into the wire nut. Twist the wire nut. Do this on each end of the wire.
Place a coating of silicone caulk on the wire nut to cover the wires and nut so no moisture will get into the nut. If you don’t have silicon caulk, wrap the wire nut with electrical tape so that no moisture can get into the nut.
Test the twisted wire with the dog collar. The collar should not beep or send a shock if you have the wires connected correctly. Bury the wire with dirt. Make a note of where the splice is for future reference if the wire corrodes or comes apart for some reason.