Hybrid earthing system?

[white111]

I am very new to electrics and my only electrical knowledge comes from books and a little experience in wiring central heating systems/boilers.

Anyway, can anyone tell me what earthing arrangement this is in my home?

(see attachment)

If it is an mixture of 2 systems how would the testing side of things work as I understand that you need to know what sysem it is for the results to make sense.

I have never really taken any notice of any earthing arrangements in the properties that I have been in before so for all I know this is a common set up. Like I said most of my knowledge comes from books. It looks to me like I have an earth spike and a earth coming from the feed cable.

In case you can't see the black cable coming from the spike and the yellow/green cable on the feed (via the connection block at the bottom) go to the joining block at the top of the board.

 

[batty]

A quick look would be originally a TT system but a TNS upgrade at some point best way to tell would be ZE using the two seperate earths one at a time and see what results are available.

And welcome to the forum.

 

[m4tty]

What batty says mate loop test seperately and see if the tns is under 0.8ohms otherwise it'll be tt. Hth

 

[kme]

I`d say TN-S. The "earth spike" looks like it could be an old lead water pipe?? Possibly the original water supply to the premises. As above, what`s the Ze

KME

 

[white111]

Thanks KME. I thought that about the water pipe but I've been told thats not the case. I have no idea what the ZE is. A friend of mine does have a tester so what should I expect for a ZE? I understand it would be a much higher if it was a TT? Or is it the other way round? Like I said most of my knowledge comes from books. No pratical experience,

 

[sparkytim]

Max 0.8 ohms for TNS could be anything on TT recommended 200 ohm max.

 

[ianmacd]

I did wonder if it was an old lead pipe too but thought it was too big. It doesn't look like it was put there for TT though (IMO anyway).

 

[Andy™]

that pipe is probably an old service pipe for something. either way, its extraneous and needs bonded.

what you have there is a bog standard TNS system

 

[batty]

[quote name='Andy

 

[green-hornet]

I would doubt the installation has ever been TT, The lead pipe is an old service pipe and may even have been the gas supply if not the water, like Andy said it would need bonding to be left in place anyway. The earth has been supplied by the DNO and is a TN-S