BS EN 60669. MK Metal Clad 13A DP Switched Connection Unit With Neon in Silver. This MK Electric Branded fused connection units are designed for connecting refrigerators, central heating boilers and other fixed location appliances. It conforms to BS 1363 Pt4: 1995 and is highly impact resistant. Its wired indicators accompanied by push-fit cord grips make for less installation time. The nominal plate dimensions are 86mm x 86mm x 47mm.