100 A single phase incoming supply

Electricity is supplied to the service head by a cable from the Distribution Network Operator (DNO) who is the company you pay your bill to. The home owner is responsible for the equipment after the electricity meter but not before. The cut-out fuse is to protect the cable should a fault occur. The isolator disconnects the supply from the meter to allow an electrician to work on the consumer unit without needing to arrange for the cut-out fuse to be removed. The protective earth cable is provided by the DNO or via an earth rod depending on the type of earthing system.