Earthe bonding

[barrym]

Can someone please tell me what the current standard os for earth bonding. On several installations, electricians have run a separate earth wire to a machine or isolator, rather than relying upon the wire armour of the cable. I have a client who has a diesel metal storage tank, complete with electrical pump. There is no earthe bonding to the tank, only the wire armour of the cable.

 

[Deleted member 26818]

The armour on an SWA cable does not have a sufficient CSA to be used as a bonding conductor.

 

[scotsparky]

The armour on an SWA cable does not have a sufficient CSA to be used as a bonding conductor.

hi Spin in some cases the SWA does comply .There is a great table Guidance notes 1 page 147,148 that will tell you if the SWA is sufficient.

 

[Deleted member 26818]

Yes in some instances, the armour of an SWA cable can be sufficient to be used as a bonding conductor.
With TT and TN-S, the minimum CSA of armour required is 48mm² and with TN-C-S 80mm².

 

[scotsparky]

didnt know exact sizes but refer to the table which has it pre calculated

 

[Deleted member 26818]

Ok my main earth is 50mm², the earthing system is TN-S.
What is the minimum CSA 2 core SWA cable required according to the tables?

 

[spidersparks]

Just looked on another thread about diesel tanks their tank was plastic presume they had some sort of metal pipe fitted some where, but if the tank is on concrete block wall as some of them are or plastic if u can prove its not earthy do you need to bond it?

 

[Jimmy Boy]

Earthing and Bonding are two distinctly different issues, you seem to be straying in to both,are you asking if the CSA of the earth in SWA is sufficient, or if the pipes and/or tank are a extraneous or exposed conductive parts ?
J