PetSafe Extra Wire KIt 

Expands your containment system beyond the initial 500 ft. of wire that accompanies the in-ground fencing kit. Each spool is 500 ft/150 meters of 20 gauge, solid core, burial-grade wire. The table below is a guide to help determine the amount of wire you will need based on the area in which you want to contain your pet. Length of wire needed will vary due to the amount of twisted wire and layout used. For proper system performance, the splice connection must be waterproof. We recommend using Gel-filled Splice Capsules and wire nuts (RFA-366) when splicing your additional Boundary Wire. (Table assumes square layout; rectangular layouts may require more wire.)