Heating cable with sealed top humidity proof (torpedo) CCPT:
The CCPT model constant power output parallel heating cable's principal feature is the heating wire which is wound in a spiral around the parallel conductor, insulated from the conducting wire except at contact points set at one metre intervals, alternating between each of the active conductors.
In this way, the heating cable forms a series of resistance running in parallel all fed by the same power cable which acts as the body.
The principal feature of the CCPT model is its special humidity proof design: The body of the cable is round and the colour of the silicone covering is gray, but the most important feature is that one of the ends is sealed with a silicone torpedo, which makes it resistant to humidity.