Cavity wall insulation. Cavity wall insulation is used to reduce heat loss through a cavity wall by filling the air space with material that inhibits heat transfer. This immobilises the air within the cavity (air is still the actual insulator), preventing convection, and can substantially reduce space heating costs.
âStandardâ wiring puts both grounds at one end of the socket. âCKâ wiring puts grounds on one side of the socket. This makes no difference to an incandescent bulb, because the filament is not sensitive to polarity. However, installing âStandardâ wired LEDs in âCKâ sockets may cause them to catch fire or blow fuses.
A cross-recess screw drive has two slots, oriented perpendicular to each other, in the fastener head; a slotted screwdriver is still used to drive just one of the slots. This type is usually found in cheaply made roofing bolts and the like, where a thread of 5 mm (0.20 in) or above has a large flattened pan head.