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Discuss Another bloody TT question in the Electrical Forum area at ElectriciansForums.net

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M

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?
 
Well for starters if the earth is buried where it goes outside it has to be 16mm anyway. So the 2.5 is no good, so if this need replacing then by the time its been traced then the rod may aswel be replaced. Plus although 70 ohms is good, you could get better i reckon
 
Thanks David but does it satisfy an earlier edition of the regs? And how are we supposed to know this? Does anyone swot up on the 14th edition?
 
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?

Another electrician, isn't, I think you are! :)
 
Well for starters if the earth is buried where it goes outside it has to be 16mm anyway. So the 2.5 is no good, so if this need replacing then by the time its been traced then the rod may aswel be replaced. Plus although 70 ohms is good, you could get better i reckon

Hi David,
If the earth is unsheathed and un-protected, would may be 25mm have to be used ?

Sorry if I'm ahead of myself, TT systems always get me !!

Millboy, as we are currently using the 17th edition of the regs, I would go by them.
I dont know if anyone else agrees?

Sav
 
Hi David,
If the earth is unsheathed and un-protected, would may be 25mm have to be used ?

Sorry if I'm ahead of myself, TT systems always get me !!

Millboy, as we are currently using the 17th edition of the regs, I would go by them.
I dont know if anyone else agrees?

Sav

Sav, you write man,

Cable to the rod need to be 25mm all the way for proper good earth!

Anything less will give you not a strong earth.
 
my understanding is that the Gn/Y insulation on the eartrhing conductor is sheathed so 16mm if not mechanically protected.
 
I'm firmly in the camp of upgrading it lol. I'll have a good look through the book tomorrow and if I can find a few regs to quote I think I can convince them to have it done. To be honest I'm annoyed that they've taken "super duper spark"s opinion over mine anyway.
 
my understanding is that the Gn/Y insulation on the eartrhing conductor is sheathed so 16mm if not mechanically protected.


comeon tel.

give the man good information

He needs a good strong earth, 25mm got to better than the 16mm to the Rod.

Go with 25mm OP.


It will give a good strong earth for best safety and all that!
 
I'm firmly in the camp of upgrading it lol. I'll have a good look through the book tomorrow and if I can find a few regs to quote I think I can convince them to have it done. To be honest I'm annoyed that they've taken "super duper spark"s opinion over mine anyway.

Don't you just love the game of "playing one tradesman off against another" ?

Tell her that you don't appreciate having your professionalism questioned, and if your word isn't good enough for her then it's best she gets someone who will tell her what she wants to hear!
 
table 54.1. 16mm. could use 50mm if you wanted to really tempt the pikeys.
 

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