Earthing arrangement

[billhopkins]

Hi

Firstly apologies in advance. I am recently qualified ( a bit later in life) and well aware I require years of experience. I was doing work in a 2 bed second floor flat. I have always done a bit of very light electrical work and had my regs over the years so I know a little. I'm now further on and by the book I am fully qualified.
I'm testing what I can at the minute for practice.

The building is very old and the incoming 3 phase supply splits to service a few flats and ground floor flats. Above the 3 phase cables there were a series of 60A main fuses. and one of them ran to the meter and then the cut of switch for my 2nd floor flat. The earthing cable from the cut off ran to an MET within this 3-phase metal box. Assume the black cable clamped to the inside of the box the neutral cable. The earth is clamped outside of the box on the right (second photo) I got a Ze of over 2 Ohms so I either tested it incorrectly (hope not) or maybe the earthing is TT ( which I doubt). I have this as a TN-S system however I realise I am inexperienced so would really appreciate feedback.
I have to go back and do some remedial so would be good to know.
Worth noting I did not disconnect the MET from this box and disconnected from the consumer unit in the flat.
Thank you

 

[billhopkins]

The MET was inside the 3 phase enclosure. It branched off to each individual cut off switch. My instinct was that it wasn't safe to disconnect the main earth from the MET going to my second door flat so I therefore disconnected the main earth at the consumer unit inside the flat. If I disconnected the MET inside the 3 phase enclosure the whole installation including the other flats and ground floor flats would need to be notified and as already stated by someone else, I don't think I should even have been inside that enclosure.

Any help/advice welcome as I have to go back. Thanks

 

[UNG]

The MET was inside the 3 phase enclosure. It branched off to each individual cut off switch. My instinct was that it wasn't safe to disconnect the main earth from the MET going to my second door flat so I therefore disconnected the main earth at the consumer unit inside the flat. If I disconnected the MET inside the 3 phase enclosure the whole installation including the other flats and ground floor flats would need to be notified and as already stated by someone else, I don't think I should even have been inside that enclosure.

Any help/advice welcome as I have to go back. Thanks

Your options are get the DNO in and / or get someone with more experience to go to site with you and do some more investigation
If it was me I would have been on the phone to the DNO pronto for them to verify the earthing arrangement

 

[Grant1987]

Your options are get the DNO in and / or get someone with more experience to go to site with you and do some more investigation
If it was me I would have been on the phone to the DNO pronto for them to verify the earthing arrangement

Yes absolutely do not touch anything inside that enclosure. Ideally you should be there when the DNO are there and between you discuss what is going on. Too much to risk with potching inside there without safe isolation procedure we all want to go home at end of day ?