Bonding of metal conduit

[cambria]

L,N & CPC fed through plastic conduit internally on the wall then through the wall to the outside then through metal conduit down wall underground across to commando sockets on brick pillar. Underground again to more sockets on another pillar. The metal conduit is not acting as a protective conductor but do go into the ground. The conduit will be at slightly different potentials at each section. Am I right in thinking this metal conduit will require main bonding. The sockets are protected by a 30mA RCCB

 

[scotsparky]

whats the joint wher plastic goes to metal?
You dont have to do a main bond but a flying lead from backboxes. Whe you are testing prove earthpath back to MET.

 

[cambria]

Havent dismantled it yet but plastic conduit on one side of wall and metal on the other dont know what the joint is if any. I think it was about 78 ohms metal conduit to MET must only be picking up ground resistance value, hence my reasoning for considering main bonding considering it to be an an extraneous conductive part.

 

[electricAl]

Follow your reasoning, but as the conduit is forming part of the actual installation it would therefore be classed as an exposed conductive part so should be earthed as per Scotsparky`s suggestion

This is a general requirement for any steelwork used as mechanical protection for cabling.

Hope that helps you

 

[cambria]

Thanks for that but just to point out the commando sockets are all plastic so no flying leads involved

 

[scotsparky]

i would try and get a bond somewhere iven if its to the back of a through box but bond it down and TEST!!