Discuss TT earth cable small and god knows where the rod is in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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Just started to test a TT system, so found the earth and thought that cannot be it for the size of the house. (See pic). So tested the Ze and got 94 so less than a 100 but I thought I’d check the connections to the earth rod. Cannot find it anywhere. I can see a new main electric feed has been put in at some point because the old one is still there.
So my question to the more knowledgable is, how long ago was a 2.5mm cable for a TT earth allowed and also should the installers of the new main (aprox 2005) into the building have picked that up ? At that point.
Turns out around that time the garage where the inlet is was connected to the house and I’m guessing they concreted over the earth rod.
upload_2019-3-31_21-30-14.jpeg
 
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Top Cat

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Arms
I am Olllllllllllld and we didn't use a black earth wire in 1900 and frozen to death! so it was probably a DIY install!
Mind you it could have been me when i had no green and yellow, or just green as it was in the 'good old days'!
 
  • Thread Starter Thread Starter
  • #3
I only go as far back as the 16th, but it has surprised me when the New main cable was installed it wasn’t changed then.
 
D

Deleted member 26818

2.5mm2 currently the minimum CSA allowed.
So any time since about 1900 to present day.
As for the colour black, again any time from about 1900 to about 1966.
 

TJ Anderson

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Mentor
Arms
Esteemed
2.5mm min if not buried and protected against corrosion and mechanical damage.

You need to locate that earth electrode
 

davesparks

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Mentor
Arms
Esteemed
I am Olllllllllllld and we didn't use a black earth wire in 1900 and frozen to death! so it was probably a DIY install!
Mind you it could have been me when i had no green and yellow, or just green as it was in the 'good old days'!
How old are these old days? If you go back far enough you'll find that green was once a phase colour.
 

Taylortwocities

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Arms
Esteemed
but it has surprised me when the New main cable was installed it wasn’t changed then.
Not suprising. As it is a TT, the earth connection is the responsibility of the customer, not the DNO.

2.5mm min if not buried and protected against corrosion and mechanical damage.

You need to locate that earth electrode
Yes. That electrode needs finding. Its a screwed termination, so should be accessible. (Its probably under the floor of that new extension!).

And a small weedy cable to the earth electrode isnt suprising. After all, its only required to carry enough current to trip the RCD.

Save yourself some digging and check with DNO to see if they can give you a PME connection.
Absolutely!!
 
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  • #17
So an update.
Installed a new earth rod and cable, ze now down to an amazing 0.29.
We pleased and well worth the effort
 
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  • #20
Just read my post lol,note to self read what you write before clicking post, 29Ω was reading 99Ω when I started.
First earth rod I have replaced so was not sure what to expect, thought maybe 45-50Ω, but was really pleased with 29Ω.
Is that about right ?.
 
D

Deleted member 26818

29 Ohms is very good.
Especially when you consider the line, transformer windings and the rod at the transformer is supposed to be 21 Ohms.
 
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