TT convert to TN-C-S yes....no....yes....no....!!!

[Vessy]

OK I know it's been thrashed out, still cant decide! Currently TT with overhead, DNO reports PME available.

So...what I have discovered....

PME has 2 protectors for earth fault MCB & RCD, TT only has RCD - PME wins
All bonding to be upgraded to 16mm for PME - TT wins
DNO to maintain earth - PME wins
If neutral lost with PME Bonding will become neutral - TT wins
Potential to become neutral path for next door through bonding - TT wins

To sum up PME would give me a good earth and more protection, but if a fault exists TT is then far safer. just can't decide. Any other benifits i've overlooked, must be as TN-C-S seems to be the standard from reading on here.

 

[telectrix]

personally i prefer the good old TN-S, can't lose with a good connection to incoming lead sheath

 

[nickblake]

personally i prefer the good old TN-S, can't lose with a good connection to incoming lead sheath

i agree with you on that one mate , i hate TT and TNCS loose a neutral on TNCS and can be costley ,One pro ive come accross with TNS is that the DNO some times do not connect the outer sheath and you then end up with a TT

Vessy think you should go for TNCS , i know ive said i hate it but 90% of the time its very reliable

 

[chloebear]

All sounds good on paper, but it will depend where the location is - had a PME installed on a new build (Overhead Feed out in the sticks) and had to convert it back to TT due to the high Ze reading on the intake.

 

[telectrix]

still prefer the wife on a bike pedalling a 3KVA Genny

 

[La Poste]

TT is a great project, great if everything is new and RCD's work like a charm.
Great if you go and check the RCD's and make sure they are working properly.
I'm in the same position at the moment, everything in the place I have done is brand new, all new wires and fuse board.
Overhead supply with TNC-S available.
I can't make my mind up.
One other thing to maybe consider is with TNC-S is you are bonding your house to the house next door and so on and if their wiring is shyte like the next door neighbours of the house I am working on at the moment then the thought of connecting my lovely gleaming re-wire to their crappy old pile of electrical hazard is making me veer to the side of TT.

 

[Vessy]

TT is a great project, great if everything is new and RCD's work like a charm.
Great if you go and check the RCD's and make sure they are working properly.
I'm in the same position at the moment, everything in the place I have done is brand new, all new wires and fuse board.
Overhead supply with TNC-S available.
I can't make my mind up.
One other thing to maybe consider is with TNC-S is you are bonding your house to the house next door and so on and if their wiring is shyte like the next door neighbours of the house I am working on at the moment then the thought of connecting my lovely gleaming re-wire to their crappy old pile of electrical hazard is making me veer to the side of TT.

Glad i'm not the only one! I don't know about next door, if it is similar to this house then that is a cause for concern! I'm swaying towards sticking with TT, everything is new and as long as RCD's work (frequent testing) then it seems the safest option (every circuit 30ma protected)

Regarding bonding the house to next door, if they were not TNC-S and I was would it try to find neutral through their bonding to my neutral? I'm thinking not.

 

[La Poste]

Not sure I understand the question but if you have an earth rod and no TNC-S then an earth fault from your property may find itself going up next doors bonding and through their neutral providing next door have TNC-S.
Your earth fault current may find the quickest way back to the star point of the transformer is through next doors bonding and neutral.
Have a look at the overhead supply cables and see if you can find the nearest supply earth, there are usually cables running down from the overhead posts into the ground.
I think I am right in assuming these are supplier earth rods.

 

[Vessy]

Yeah I guess it would, all properties here have 100ma RCD Isolators so shouldn't really be a problem, but if that fails then yes the easiest route for an earth fault could be through water pipe to neighbours TNC-S setup, and all through 30 year old 2.5mm bonding conductors!! Pole outside house has cables running down but there is also a street light next to it, could be earth rod or supply to light. I wondered if the earth rod was a solid flat plate running down the pole which I have also seen

 

[Vessy]

As DNO have confirmed PNE there should be a suppliers earth close by, TT Ze should in theory be nice and low, testing next week to confirm, think i'm defo staying TT!

 

[chloebear]

I like the " in theory " bit - good luck

 

[Vessy]

I like the " in theory " bit - good luck

My glass is always half full! until it all goes wrong!!