bonding steel girders [stanchions]

bobsteroo · Oct 19, 2010

i have been working with this electrician giving him a hand we have had a disagreement
about bonding
the main building has a 3 phase tns supply from there a 16mm 4 core swa and seperate 16mm earth goes to a brick built building a new extension has just been constructed
with 6 seperate steel stanchions or girders which or not connected with steel purlins or similar i say you should take a seperate earth back to the main dis-board in existing building
and run an earth between girders he says he will put an earth rod by 1 of the girders and run an earth between girders can any one settle this thanks

nickblake · Oct 19, 2010

nope you are correct its structual steel and should be treated as water gas etc and bonded back to the board ,

WayneL · Oct 19, 2010

bobsteroo said:
i have been working with this electrician giving him a hand we have had a disagreement
about bonding
the main building has a 3 phase tns supply from there a 16mm 4 core swa and seperate 16mm earth goes to a brick built building a new extension has just been constructed
with 6 seperate steel stanchions or girders which or not connected with steel purlins or similar i say you should take a seperate earth back to the main dis-board in existing building
and run an earth between girders he says he will put an earth rod by 1 of the girders and run an earth between girders can any one settle this thanks

That will just make things worse, IMO, they will definitely be introducing earth potential into the building.

I assume you are installing a CU and earth bar in this new building.

The steel stantions need only be bonded to this and the 16mm CPC will act as both earthing & bonding conductor.

The earth bar in the new building is termed an EMT (Earth Marshalling Terminal), and can be treated as a remote MET - all earthing and bonding can be run to this. (This is so long as the CPC of the feed to the building is of sufficient size to act as a bonding conductor as well)