main bonding conductors

[iamelectric]

hi can anyone tell me the what the maximum value of a main protective bonding conductor is

 

[44ALLAN]

very low mate

 

[Deleted member 9648]

There isnt a maximum value in bs 7671,though 0.05 ohms is recommended in the earthing and bonding GN

 

[iamelectric]

i cant find the answer anywhere but 0.05 is only if you are measuring between two extraneous conductive parts when access to the bonding connection is not possible

 

[Deleted member 9648]

i cant find the answer anywhere but 0.05 is only if you are measuring between two extraneous conductive parts when access to the bonding connection is not possible

Havent got the GN to hand,but I thought it was ECP to MET?....which equates in effect to the resistance of the bonding conductor,might be wrong though.

 

[44ALLAN]

hi can anyone tell me the what the maximum value of a main protective bonding conductor is

Better question is...............do you know why you are putting a 'Main' bond on and what it is for?
I guess you know why?

So.............will it matter if it's 0.05ohm or 500ohm?

 

[Risteard]

Havent got the GN to hand,but I thought it was ECP to MET?....which equates in effect to the resistance of the bonding conductor,might be wrong though.

No. That is simply suggested as a means of verifying that extraneous conductive parts are effectively connected to the main protective bonding conductor. BS 7671 does not limit the resistance of the main protective bonding conductor and so there is no requirement to use a conductor with a greater csa to achieve the mythical 0.05 ohms from the MET.