The cold tail is the part of the heating mat or cable that does not heat up and is used for making the electrical connections to the thermostat or junction box. It is constructed of three elements, live (brown), neutral (blue) and earth (yellow and green) and is usually black.
The coldtail on Heat Mat’s mats and cables is usually 2.0m long and electricians can extend the coldtails if required. Although coldtails do not need to be laid under the final floor covering part of them always is as the coldtail connection has to be placed beneath the floor covering.
Most systems have only one cold tail however in some specialist systems, such as Heat Mat’s Underlaminate System, there is a cold tail at either end. In these circumstances both coldtails must be connected to the thermostat or junction box and it is wise to label each heaters coldtails with a number so they can be matched up when the required electrical tests are carried out. With dual coldtail systems one coldtail will have a live and earth wire and the other coldtail a neutral and earth wire.