Earth Rod before PME

[stilllearning]

A relative of mine has just discovered that the house they've been living in for 7 years doesn't have an Earth! It seems that whoever rewired the place last connected the main earth cable into the cutout of a TNS system but there was no actual link from the incoming armour of the cable to the earth block.

Their sparky discovered this when he came to test after installing a couple of sockets. They called out the DNO who confirmed his suspicions. The DNO then advised that either an earth rod be fitted or that they should apply for PME.

Apparently if they opt for PME it will take about six weeks to be installed.

My question is, what should they do in the meantime? They have an RCD which they know does trip but how effective will this be if there isn't a 'proper earth'? Will the sparky fit an earth rod untill PME is available.

Just curious really - but would appreciate your thoughts.

 

[Spark123]

The only real way to make the installation safe at the moment is to RCD protect it and install an earth rod to make it into a TT system. The on site sparky should be able to advise on what size RCD is required. This is probably the best way forwards as at the moment, in the event of a fault, the earth path may be through you as opposed to the electrical system. How are they testing the RCD out of interest? In order for it to provide protection against indirect contact there needs to be an earth present?

 

[stilllearning]

Thanks. That's what I was curious about i.e how effective the RCD would be if there isn't a decent earth. From what I can gather the man from the DNO tested it a socket and it tripped eveything??

 

[Spark123]

There may be an earth path through the MEBs/water pipes etc though these should not be relied upon. Also, are the lights etc also on an RCD protected circuit?

 

[stilllearning]

Yes, the whole house is on a 30ma RCD. I'll try to persuade them to have an earth rod fitted before the PME 'arrives' but PME is going to cost £98, not sure what a sparky would charge to install a rod.

 

[stilllearning]

...just another thought. If the system was originally supposed to be TNS anyway couldn't the DNO or sparky have connected the main earth cable to the armour of the incoming supply - at least until the PME is installed?

 

[Spark123]

No, only the DNO are allowed to make this connection to their cable.