National Inspection Council for Electrical Installation Contracting a register of approved electricians. It was incorporated on 10 August 1956, and since 1 October 2005, it has been registered as The Electrical Safety Council. Electrical contractors register with the organisation to become approved contractors, meeting the NICEIC's specification of training. If work undertaken by the approved contractor is not up-to-standard, the NICEIC will correct it if necessary. Work is checked by 54 local Area Engineers. Many local authorities only give work to NICEIC-approved electricians. Most electrical items in domestic wiring are controlled from the consumer unit with its residual-current device (RCD), which since 2001 has to be installed.
Electrical bonding a TT system where the impedance is high due to the lack of direct connection to the transformer neutral, an RCD must be used to provide disconnection. RCDs are also used in other situations where rapid disconnection of small earth faults (including a human touching a live wire by accident, or damage) is desired. Equipotential bonding involves joining together metalwork that is or may be earthed so that it is at the same potential (i.e., voltage) everywhere. Such is commonly used under transformer banks by power companies and under large computer installations. Exact rules for electrical installations vary by country,