Unused Earth Rod in Garage.

Is it definitely a rod passing through the floor, not a connection to steel in the floor?

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.

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.

RichardCS2: 
 

Is it definitely a rod passing through the floor, not a connection to steel in the floor?

I assumed that it is a rod. Why would anybody install an earth grid in a modern detached domestic U.K. garage concrete floor?

Z.

Zoomup: 
I assumed that it is a rod. Why would anybody install an earth grid in a modern detached domestic U.K. garage concrete floor?

Ah! Had I known about these things then, I would have had the rebar mesh in my garage floor (circa 60 sqm) made available as a foundation electrode. My question is why would you not?

Chris Pearson: 
 

Zoomup: 
I assumed that it is a rod. Why would anybody install an earth grid in a modern detached domestic U.K. garage concrete floor?

Ah! Had I known about these things then, I would have had the rebar mesh in my garage floor (circa 60 sqm) made available as a foundation electrode. My question is why would you not?

What is its purpose Chris? And why was it left disconnected?

Z.

Why would anybody install an earth grid in a modern detached domestic U.K. garage concrete floor?

A lot of concrete floors these days will have steel grid reinforcement anyway for structural reasons - if it was there anyway making it available for bonding, or even as an electrode, seems quite sensible.

   - Andy.

Ah! Had I known about these things then, I would have had the rebar mesh in my garage floor (circa 60 sqm) made available as a foundation electrode. My question is why would you not?

Because it has a sheet of polythene under it.

Sparkingchip: 
Because it has a sheet of polythene under it.

Good point! However, the floor (and my pit) is not as dry as you might think. The moisture evaporates and the atmosphere does not make things rust, but if I put down a plastic sheet, it gets wet underneath.

The fact remains that I would have had some form of foundation electrode installed (under the polythene if necessary) had I known.

AJJewsbury: 
 

Why would anybody install an earth grid in a modern detached domestic U.K. garage concrete floor?

A lot of concrete floors these days will have steel grid reinforcement anyway for structural reasons - if it was there anyway making it available for bonding, or even as an electrode, seems quite sensible.

   - Andy.

So was it installed for possible E.V. charging use? The garage is very small and a modern car would struggle to get into it. Also the single garage is cluttered with stuff including a freezer and tumble dryer. The car is forced to sit on the drive.

Z.