TT system

[BristolSpark]

Hi all

I have this job to look at. Its a TT system. I can see the earth coming into the building but unable to find the earth rod on the outside.

They are hoping for a board change dual rcd and do away with there old front end rcd and rewireable fuses.

I was hoping to upgrade the incoming earth to 16mm. But like I said unable to trace rod. would 10mm earth still be adequate with 25mm tails. I dont fancy trying to bang another rod down with tarmac paving outside house. also dont have cat scanner.

please help.

 

[Mac]

Hi all

I have this job to look at. Its a TT system. I can see the earth coming into the building but unable to find the earth rod on the outside.

They are hoping for a board change dual rcd and do away with there old front end rcd and rewireable fuses.

I was hoping to upgrade the incoming earth to 16mm. But like I said unable to trace rod. would 10mm earth still be adequate with 25mm tails. I dont fancy trying to bang another rod down with tarmac paving outside house. also dont have cat scanner.

please help.

Needs to be accessible mate.Can't you just run a 10mm meter bit through the tarmac.10mm on a TT system is fine

 

[BristolSpark]

I was chatting to someone the other day they said it might be fine with the existing 10mm cable. All I was thinking is I cant find the existing earth rod but they have the cable inside the property. If I could find the rod maybe I could pull another 16mm cable back through.

Did not fancy banging a new earth rod as I dont know whats below me. Services or the main incoming supply.

So are you saying that regardless a 10mm earth cable is fine on a TT system. In that case I can just continue with job and with no problem keeping cable as exisiting.

cheers mac

 

[OilBeDamned]

Hi all

I have this job to look at. Its a TT system. I can see the earth coming into the building but unable to find the earth rod on the outside.

They are hoping for a board change dual rcd and do away with there old front end rcd and rewireable fuses.

I was hoping to upgrade the incoming earth to 16mm. But like I said unable to trace rod. would 10mm earth still be adequate with 25mm tails. I dont fancy trying to bang another rod down with tarmac paving outside house. also dont have cat scanner.

please help.

From what I remember the minimum expectations when we were installing 25mm tails was a 16mm earth.

 

[Mac]

From what I remember the minimum expectations when we were installing 25mm tails was a 16mm earth.

Minimum size of earth on a TT system is 6mm.I always use 10mm thou.It's in the OSG and the BRB

 

[Mr Mark Sparks]

you need to either find the stake or put a new one in
its location and type will be required for the eic
also 10mm is ok

 

[flukey]

From what I remember the minimum expectations when we were installing 25mm tails was a 16mm earth.

not on a tt system

 

[BristolSpark]

Mac

I thought a 10mm was ok as long as RCD was in place to. so split board dual rcd is ok for that. will I be able to then use the exisitng 10mm or do I really have to run a new one and new stake.

 

[Mr Mark Sparks]

as said in my previous post you will need the stake info for your cirt

 

[BristolSpark]

what info for the stake would be required can you elaborate for me this cheers m8. . i.e 1.2m 25mm earth rod. Ze you can do at the board with exisitng cable.

 

[Mac]

Mac

I thought a 10mm was ok as long as RCD was in place to. so split board dual rcd is ok for that. will I be able to then use the exisitng 10mm or do I really have to run a new one and new stake.

10mm is fine mate.But the earth rod needs to be accessible.If the old is buried,you will need to put a new one in.All circuits on a TT system should be RCD protected anyway.

 

[Mr Mark Sparks]

http://www.elecsa.org.uk/downloads/public/BS7671 17th edition Electrical Install.pdf

section j on this cirt

 

[OilBeDamned]

not on a tt system

It may be minimum requirement but im going from what we used to install as a supplier.

 

[flukey]

It may be minimum requirement but im going from what we used to install as a supplier.

6mm`s minimum, 10mm`s fine

 

[OilBeDamned]

6mm`s minimum, 10mm`s fine

Read reply above.

I used to work with Scottish Power and I am only passing on what we were required to install as policy.