Should the unistrut be bonded to the installations metal work. A measurement from the Starter Panel to the metal unistrut reads 0.12megaohms but as the flex is cable tied to it is it a requirement? The flex is ran from a plastic junction box mounted on the unistrut, the flex is ran from the JB to a 110v solinoid approx 1 meter away. Thanks for your help guys.
If it did present an earth potential is the easiest way to get this to comply by just linking the earth ring of the gland closest to the unistrut and connecting it to earth that way through the armour of the cable?
If it was an extraeous-conductive-part as far as the installation was concerned it would need main bonding - i.e. full sized bonding conductor all the way back to the MET (e.g. 10mm² copper for a typical domestic, probably a lot larger for a industrial) - that could indeed be 'borrowed' from a more local circuit's c.p.c. but the size requirement all the way back to the MET remains, so it's only usually practical for submains to local DBs rather than small final circuits as their c.p.c.s would be too small. With steel armour used as the c.p.c. and PME earthing it's even harder as the requirement for equivalent conductance to copper pushes the required c.s.a. up by a factor of 8 or 9.
If for some reason you needed supplementary bonding (e.g. it was some kind of special location and the metalwork may introduce a potential from elsewhere in the installation but not directly from outside it), then bonding to local c.p.c.s would be more much more usual.
If it did present an earth potential is the easiest way to get this to comply by just linking the earth ring of the gland closest to the unistrut and connecting it to earth that way through the armour of the cable?
If it was an extraeous-conductive-part as far as the installation was concerned it would need main bonding - i.e. full sized bonding conductor all the way back to the MET (e.g. 10mm² copper for a typical domestic, probably a lot larger for a industrial) - that could indeed be 'borrowed' from a more local circuit's c.p.c. but the size requirement all the way back to the MET remains, so it's only usually practical for submains to local DBs rather than small final circuits as their c.p.c.s would be too small. With steel armour used as the c.p.c. and PME earthing it's even harder as the requirement for equivalent conductance to copper pushes the required c.s.a. up by a factor of 8 or 9.
If for some reason you needed supplementary bonding (e.g. it was some kind of special location and the metalwork may introduce a potential from elsewhere in the installation but not directly from outside it), then bonding to local c.p.c.s would be more much more usual.
