Metal Consumer Unit on TT supply BS7671 Amendment 3

Problems when installing a metal consumer unit on a TT supply (those with an earth rod / electrode). Due to the high earth loop impedance on TT supplies, a fault between line and earth will not cause sufficient current flow to blow the supplier's fuse. This would result in all of the metalwork within the installation becoming live, with a serious risk of electric shock. Previously, an RCD in an insulated enclosure would be used before a metal consumer unit to disconnect the supply if such a fault occurred. However as BS7671:2008 Amd3 requires that consumer units and similar enclosures are 'non-combustible', i.e. metal, this is no longer an option. Website: http://xo4.uk/?ttT