Size of main bonding

[moosey86]

Okay chaps, I need a dispute settled so thank god that he created the iPhone. How do u work out the size of the bonding to the gas and water in an industrial premises? Any takers please

Cheers

Moosey

 

[johnboy6083]

on a power station i jsut finished on, evertything was a minimum of 70mm2 and theyb ran 240mm2 bare earth along all of the ladder rack! slightly over the top!

dont know about your situation though matey. Isnt there guidance in a guidance note, installation designers?

 

[Notsosmart]

According to Section 544 in the BRB;
If not PME The cross sectional area of a bonding conductor need not exceed 25mm2, but if PME on site then a bonding conductor shall be selected according to the largest neutral conductor.

Table 54.8 ~ Where PME conditions apply

Copper equivalent cross sectional area of the supply neutral conductor in relation to Minimum copper equivalent cross-sectional area of the main protective bonding conductor
35mm2 or less = 10mm2
35mm2 up to 50mm2 = 16mm2
50mm2 up to 95mm2 = 25mm2
95mm2 up to 150mm2 = 35mm2
Over 150mm2 = 50mm2

 

[moosey86]

Cheers notsosmart, I thought it was to do with the neutral supply conductor and I was sure 50mm was max. It's a factory with a supply transformer on site I take it that rule applies then...

Cheers

 

[Andy Greaves]

If the factory has its own HV supply then chances are the earthing arrangements are TN-S.