working to 17th

[ezekiel]

if you were to add to an existing lighting circ, would that circ need an rcd to be added if one did not exist, also if bonding was undersized would that need upgrading or could it be identified on forms as requires improving - (find all this very confusing)

 

[GaryMo]

The work you carry out should comply with BS7671. That would mean if installing additional lighting to an existing lighting circuit then the cables you install must be RCD protected if they're concealed and less than 50mm from the surface.
There are numerous ways of complying, RCD protection at the origin of the circuit would be my choice but you could use flexishield cable for switch drops, run the switch drops through earthed metallic conduit or run them in surface PVC trunking.....

Have a read of http://www.esc.org.uk/forum/

Also read regulation 131.8

No additions or alterations should be carried out unless the conditions of the existing installation or equipment will be adequate for the altered circumstances. Earthing and bonding arrangements should also be adequate considering the protective measure against electric shock is ADS which relies on protective earthing, protective equipotential bonding and automatic disconnection in case of a fault.