Flat Supply - Dubious earths?

[westie101]

Max permissible Ze for TNS = 0.8

Max permissible Ze for TNCS = 0.8, though expected to be below 0.35

2.1 ENA Engineering Recommendation P23/1 gives Guidance relating to Consumers Earth Fault Protection and advice required from Public Electricity Supply Companies.
2.2 Within this document are published suggested maximum values of Earth Loop Impedance (ELI), primarily for use as a guide to designers of private installations for consideration of their protective devices. The ELI values should allow the service termination fuse to operate within 5s in line with BS7671 and CP331.
2.3 In line with these suggested guidance notes **** has adopted the following figures as acceptable values of ELI to be measured at the incoming service termination where an earth terminal has been provided
Non PME System = 0.8 ohm
PME System = 0.35 ohm (Higher values can be accepted up to 0.8 ohm)
(The value for a PME system being lower as to be expected with the combined neutral / earth
configuration)

 

[GeeTee]

The cable coming out of the bottom of the grey MEM use unit for the shower looks like either 10/16mm twin and earth is that coming from the silver metal clad Bill switch fuse where the main feed comes into the flat or does it run down back to the meter position ?

It is certainly not connected to the silver metal clad switch. That has the incoming feed going into it and nothing coming out, it is labelled "Cooker", but there is no typical cooker type outlet in the kitchen (there's a standalone gas cooker in there now) so I assume that circuit was stripped out at some point.

As for it running back to the meter position - I can't say for sure but I certainly saw no sign of it in that area. Bit of a mystery really, I'll have to get the floor up and see where it goes!

 

[GeeTee]

.... I would tighten that up as my first plan of action, as at least you should get a reasonable connection to the DNO earth through that, via the other flats which have the copper braiding attached. It's not 'proper' by any means but the other way would be to attach an earth from the 8-way to the switch or up through to the flat, but I'd sooner not have you messing around near those old rubber cables.

I'll tighten that strap up right away. And no, I wouldn't contemplate trying to pull an earth through from the meter to the flat, as for attaching an earth from the 8-way to the switch - I didn't notice any external terminal on that switch that might be for an earth and I sure as hell ain't opening it!

If the rubber cables need replacing (which they clearly do) , then the electrician can fit a new cutout and pull a new earth through at the same time as the submain and hook the lot up to the DNO earth block I'm supposing.

 

[bernardgreen]

Who is responsible for the maintainance of communal areas and services to the flats ?

This could be the freeholder of the block or a management group / company.

It is very likely they are the people who need to ensure a safe supply of electricity to the flats if the cut out meters etc are in a communal area.

They have a duty of care and it is very likely they can be held liable if the supply arrangements are not of a suitable standard.