I have drilled 2 holes for 2 heat cables in each enclosure. Only one hole in the small enclosure where i want to use only one heat cable. I have drilled the wholes in the back of the enclosures and in one enclosure in the side, but all very low near the floor of the enclosure where the heat cable was laid. The heat cable passed through the hole from the outside into the inside and is laid on an area on the floor and covered with tiles. That area will be the warm side. The heat cable remains on 12 hours during the day and during the night off.