Another bloody TT question

[Millboy]

Hi chaps, This is part looking for advice, part moan. Bear with me..

Ive been asked to look at a rewire, no spec just what I think would be necessary (usually a mid range install, nothing fancy but no £1 sockets etc.) Now the install is 40-50 years old and is an overhead supply, as is common to the area the house is in. Looking at the earth coming in it is 2.5mm unsheathed, partially protected by rusty metal capping, and goes out the wall, disappearing under the concrete at the rear of the house, never to be seen again.

I included in my price a new rod, earth pit etc etc. Another electrician has been and told the client that the existing rod is fine and he's tested it blah blah blah (I tested it at 70 ohms). The point isn't that the reading is too high, IMO on a rewire everything needs to be put right ie. the rod needs to be accessible, connections protected etc. and that I'm not happy with the bare minimum size earthing conductor.

That's the moan over with now the question... The client says they want to go ahead with the rewire but keep the existing earth "if it satisfies the regs". Now I know there's a reg that says the connection should be accessible and protected from corrosion in the 17th, but if it was ok to bury them 40 years ago, then can it stay and not conform to the
current edition of regs?

 

[sedgy34]

Pikeys can play a game of tug of war with a 25 mm earth lol

 

[Steve_P]

You're assuming that the other sparky will even issue paperwork. Been to a few jobs recently where new CU fitted by "qualified electrician" has no cert with it at all, plus loads of deviations from the regs which are just unacceptable. These cowboys getting more prevalent in the current economic climate it seems....

There's a few round here doing the same, 2 that "know electrics" and have been used for years regardless of what they know and 1 that just took some exams and is now "qualified". None of them can read it seems but they do generate a lot of work for the rest of us.

Anyhow, back to the rod question, sometimes you have to tell the customer what they're getting even if it isn't what they want.

 

[infinity]

As spin notes 2.5mm is acceptable if protected from corrosion and mechanical damage and not buried.

If 2.5 is used then main bonding will only need to be 6mm minimum as well.

6 mm bonding is acceptable right up to 10mm main earth in fact.

 

[Guitarist]

As spin notes 2.5mm is acceptable if protected from corrosion and mechanical damage and not buried.

If 2.5 is used then main bonding will only need to be 6mm minimum as well.

6 mm bonding is acceptable right up to 10mm main earth in fact.

Good point. However, many TT systems are now being upgraded to PME (I am right now organising one myself) so it is better to install 10mm main bonding.

 

[Steve_P]

Someone round here just managed to charge a load of people to replace their earth rods. Charged them more than a PME conversion which was available for all the properties. Goes to show that people will believe what bert from the pub tells them.

 

[Engineer54]

Someone round here just managed to charge a load of people to replace their earth rods. Charged them more than a PME conversion which was available for all the properties. Goes to show that people will believe what bert from the pub tells them.

And probably left them with Ra values of far more, from than what they replaced too!! After all they only need to attain 200ohm at the rod these day's. What's the betting also, that the new rods are all of the thin twig variety!!! .... lol!!

 

[Guitarist]

And probably left them with Ra values of far more, from than what they replaced too!! After all they only need to attain 200ohm at the rod these day's. What's the betting also, that the new rods are all of the thin twig variety!!! .... lol!!

Anything for maximum profit...

 

[AIM]

I always install 16mm G/Y to rods so if PME is put in later no cable changes are needed. I also don't waste time with 3/8" rods any more. With 5/8" rod and couplers I always get 50 Ohms, or less, at first test.