main earth bond..

[bigspark17]

Does the main earth bonds i.e.. Water , gas, oil have to go to 'MET' at suppliers cutout next to meter or in consumer unit suffice. What about a comercial premesis where you have sever sub boards can it come off the nearest db?

 

[Sintra]

MET unless there are adequate EMT's at other locations.

 

[telectrix]

what he said ^^^^^.

 

[bigspark17]

So aslong as the sub main feeding the sub boards is >10mm conductor and labelled correctly this would be ok from a sub board?

 

[Badged01]

Assuming 10mm is whats required under the regs and every sub is connected to the MET by 10mm, then for me you can bond to any sub as there is a 10mm path back to the MET.

 

[kingeri]

I'd agree with Badged, although where possible I always connect the main bonds to the same place as the main earthing conductor, i.e. the MET. On larger installations I can see where it would be more practical to connect main bonds to a closer EMT. But don't do it out of laziness of to save a bit of cable!

 

[Engineer54]

So aslong as the sub main feeding the sub boards is >10mm conductor and labelled correctly this would be ok from a sub board?

On large commercial and many industrial installations, bonding cable sizes could well exceed 10mm.

Generally nothing wrong connecting locally bonded metalwork etc to the EMT of a sub-main DB. In fact it would be crazy to take every bonding connection directly back to the installations MET. In many instances the frame of the building will be steel/iron, Once this steel framework has been solidly bonded to the installations MET, connections to other extraneous services etc, can be effectively bonded to the buildings steel framework.