Bonding size

[yellowvanman]

Just done an EICR and for a 3 phase board the tails were 35mm, but the DNO fuses were your standard 100A. Bonding conductors are 10mm. Any comments?

 

[Guest55]

tns , tncs , tt ?

 

[Guest55]

not that it matters much , i dont see any issues with 10mm.

 

[Richard Burns]

I don't see a problem there, what is worrying about it?

 

[smuggler]

should the earth tails not be at least 50% mm2 of the L N tails

 

[smuggler]

should the earth tails not be at least 50% mm2 of the L N tails

sorry just seen its bonding your talking about oooops

 

[yellowvanman]

Sorry it was TNC-S. So table 54.8 applies. If it was an issue would be easier to change the tails for 25mm rather than change the bonding cable.

 

[telectrix]

bonding conductors need to be a min. of 50% of the required earthing conductor as determined by the adiabatic equation. the actual size of the main earthing conductor that is fitted is irrevelant as long as it is ≥ that determined by the adiabatic and complies with minimum size requirements.

 

[yellowvanman]

bonding conductors need to be a min. of 50% of the required earthing conductor as determined by the adiabatic equation. the actual size of the main earthing conductor that is fitted is irrevelant as long as it is ≥ that determined by the adiabatic and complies with minimum size requirements.

That doesn't apply if TNCS. Adiabatic says 10mm is enough for the main earthing conductor.

 

[Engineer54]

On TNC-S (PME) systems, earthing/bonding conductors are based on the incoming Neutral conductor, not the phase conductor!!

 

[yellowvanman]

On TNC-S (PME) systems, earthing/bonding conductors are based on the incoming Neutral conductor, not the phase conductor!!

Bonding only.