Unused Earth Rod in Garage.

mapj1: 
 

It might be an earthed grid in the floor, as suggested in the regs for PME farms but almost never done, to raise the concrete floor potential to that of the local CPC. (what is normally done  is TT..) 

Can you measure the effective electrode resistance ? That will tell you if it is going  to metal above or below the Damp Proof Course.

Some countries regulations require wires to foundation steels etc to be wired in pairs, so that you can test through the resistance of the buried joints  without digging anything up - if it is a low resistance from the wire tail at one place on the mesh to a similar  wire tail attached at another point then you can be sure that the connection to the mesh from both wires is also in  good order. (and that once reconnected it would require a double failure to lose the earthing totally.) It is also an easier ‘dead’ test than planting test electrodes and so on in a built up area.

Always possible someone is working to a continental standard achieving equivalent safety to BS7671 by a non standard means ?

Mike.

The earth rod is covered by a plastic earth box with warning label. I assumed that it is a rod. The detached garage is domestic and modern. I have not tested the “rod.”

Z.

mapj1: 
 

It might be an earthed grid in the floor, as suggested in the regs for PME farms but almost never done, to raise the concrete floor potential to that of the local CPC. (what is normally done  is TT..) 

Can you measure the effective electrode resistance ? That will tell you if it is going  to metal above or below the Damp Proof Course.

Some countries regulations require wires to foundation steels etc to be wired in pairs, so that you can test through the resistance of the buried joints  without digging anything up - if it is a low resistance from the wire tail at one place on the mesh to a similar  wire tail attached at another point then you can be sure that the connection to the mesh from both wires is also in  good order. (and that once reconnected it would require a double failure to lose the earthing totally.) It is also an easier ‘dead’ test than planting test electrodes and so on in a built up area.

Always possible someone is working to a continental standard achieving equivalent safety to BS7671 by a non standard means ?

Mike.

The earth rod is covered by a plastic earth box with warning label. I assumed that it is a rod. The detached garage is domestic and modern. I have not tested the “rod.”

Z.