Earthing/ Bonding???

[a.e.s]

Hi I am currently training to be an electrician and whilst wiring a factory the other day I was wondering what denotes the Size of bonding cables. we are working on a 3 phase system with a 300 A head. I was told to do the water, gas and structual bonding in 50mm, which I questioned saying it seemed a bit excessive. My boss told me you could get away with 35 mm but to do it in 50 any way. When I asked how you can find out what size to use he just said it was all to do with the incoming neutral and a certain ratio between the 2. I try to talk to my boss as little as possible so I didnt ask for an explanation. cheers

 

[Spudnik]

What size are the tails?

 

[Guest123]

A 50mm bonding conductor is only needed for supply tails of 150mm and above.

 

[scotsparky]

A.E.S the BRB tells you page 134 Table 54.8. TT systems are slightly different but that table is a good guide.