An improved design for an electrical insulated "through" boot for a bare joint area formed by two electrical conductors made of a molded member arranged longitudinally around the joint area and having a main body portion with opposed flap members. Each flap member is coextensive with the main body portion and has a distal end. When the molded member is arranged around the joint area, the distal end of each flap member is wrapped around each other in an overlapping manner to form a seal and to enclose the joint area. The ends of the boot can be secured in place by clamps or wire ties. The boot is easily removed without being destroyed for maintenance of the conductors and is therefore reusable. A further embodiment is for a tee boot which has a perpendicular leg which slips over the riser and which has the opposed flap members which are overlapped over the joint area of the bus bars, and a still further embodiment is for a spout boot which involves two pieces wherein one piece is inserted into the other for the overlapping feature around the joint area. Further embodiments provide an end boot and an end cap boot which also increase the creepage distance for the current leakage to prevent breakdown of the voltage source.