5.8.3 - Earth-free bonding

The Regulations permit the provision of an area in which all exposed metal parts are connected together, but not to earth. Inside the area, there can be no danger, even if the voltage to earth is very high, because all metalwork which can be touched will be at the same potential. Care is necessary, however, to prevent danger to people entering or leaving the area, because then they may be in contact with parts which are inside and others which are outside the area, and hence at differing potentials. A notice must be erected to warn that the bonding conductors in the system must not he connected to earth, and that earthed equipment must not be brought into the situation.

As in the case of non-conducting locations, this type of installation is unusual, and must only be undertaken when designed and specified by a fully qualified electrical engineer. The area inside the protected system is often referred to as a 'Faraday cage'.