TT or TN-C advise Please

[KLV74]

Hi this is my first post and would really appreciate some advise regarding my electrical service head. Is it TNC or TT supply ?

I have an incoming cable from underground which has a fabric wrap type insulation. Out of the ISCO service head I have a red live and black neutral (no earth connection) going to my meter then 100Ma RCD and then onto an old consumer board (pop out MCB’S).

The only Earth I have is via my lead water pipe. I have checked Earth loop with Megger MT1553 and get a value of 4.5 Ohms at the board with earth disconnected (meter attached to earth from lead pipe and lincomming live) and when connected testing via socket connection 8.5 Ohms with earth reconnected.

Many Thanks K

 

[craig1000]

The PME connection charge would have made MUCH more sense than your earth rod charge!!

In what way? Not on what I was being told by the DNO at what they wanted to charge me or the customer for changing to PME.

 

[Engineer54]

Why, ....because the TN earthing protection is going to be far superior than the Ra you probably gave the customer!!

 

[craig1000]

I am not disputing that And I made that point to the customer. BUT we are talking cost here are we not if I refer to your original comment of

'The PME connection charge would have made MUCH more sense than your earth rod charge!!'

I took this as you saying it would have been cheaper for the PME, in this case due to what I was being told it would cost by DNO it would not have been. I cannot MAKE a customer spend money and there was another option that achieved desired values to satisfy regs. If it had not of done I would of insisted there was no other way! I also didnt suggest the rod idea, I was saying PME only but then after they had 'chatted with a mate of a mate' they asked can I not install rod instead. I could not say no as iyt was a viable option to achieve although not the best method and explained that to them.
Money was their only concern, funny though how they were happy spending a few grand on the new kitchen and bathroom but not a little more for a safer electrical installation! ;-( Baffles me theses customers!

​

 

[KLV74]

Hi bert im new to this forum i dont thik i can attach a pic until ive reached 6 posts, as soon as i have i will put one up or can email if you want

 

[Engineer54]

I am not disputing that And I made that point to the customer. BUT we are talking cost here are we not if I refer to your original comment of

'The PME connection charge would have made MUCH more sense than your earth rod charge!!'

I took this as you saying it would have been cheaper for the PME, in this case due to what I was being told it would cost by DNO it would not have been. I cannot MAKE a customer spend money and there was another option that achieved desired values to satisfy regs. If it had not of done I would of insisted there was no other way! I also didnt suggest the rod idea, I was saying PME only but then after they had 'chatted with a mate of a mate' they asked can I not install rod instead. I could not say no as iyt was a viable option to achieve although not the best method and explained that to them.
Money was their only concern, funny though how they were happy spending a few grand on the new kitchen and bathroom but not a little more for a safer electrical installation! ;-( Baffles me theses customers!

Idiots, ...unfortunately come in all sorts of shapes and sizes!! And typical of those that are more interested in what a new kitchen looks like, than whether it actually works as a kitchen. The very last thing that would enter these idiots heads is the safety of their families!!

What cost did the DNO want to charge for a head conversion to PME?? Which is about 15 minutes work!!

 

[craig1000]

Idiots, ...unfortunately come in all sorts of shapes and sizes!! And typical of those that are more interested in what a new kitchen looks like, than whether it actually works as a kitchen. The very last thing that would enter these idiots heads is the safety of their families!!

My views exactly, really grinds my gears.

As I say I would always go for the best available method if down to me. I as I also say cannot force clients into work that is better if there is a alternative available. In short had I not done the rod then he would have got AN Other to do so. The rod did achieve decent values in fairness but still not as good as the PME would have done.

Left it better than found anyhow as it was previously earthed through the water pipe bond! ;-(

 

[craig1000]

I cant remember now exactly, in the region of £250.00 upwards.

Firstly they were almost gona do it for nothing which was happy days then they changed their tune!

I was trying to argue they should maintain their MET if provided, and there was a crappy piece of very small uninsulated cable coming off the lead sheath which was not in the CU but under the floor below and probably an old TNS earth off the supply cable. In which case I said they were providing an Main Earth which had broke down/failed and it should be up to them to maintain. they wouldn't have it though ;-(

 

[Engineer54]

I cant remember now exactly, in the region of £250.00 upwards.

Firstly they were almost gona do it for nothing which was happy days then they changed their tune!

I was trying to argue they should maintain their MET if provided, and there was a crappy piece of very small uninsulated cable coming off the lead sheath which was not in the CU but under the floor below and probably an old TNS earth off the supply cable. In which case I said they were providing an Main Earth which had broke down/failed and it should be up to them to maintain. they wouldn't have it though ;-(

If there was positive sign's of a previously supplied DNO earth provision, they would need some very good excuses why they are not prepared to maintain that earth provision!! Calls to the Area Engineer and if necessary to the ombudsman usually gets results!!

£250 is an absolute pee take, that i would have not let them get away with without a fight!! lol!!

 

[bertt]

Hi,


Ok I get it now.
I'm new as well on forum but use properly the tools from main menu available and check the format for pictures and use the browse from file not URL .Than don't forget to press Upload button and That is it! Thank you.

bertt
London

 

[KLV74]

Hi Bertt Pleasefind attached picture

 

[KLV74]

Thanks for all your help, I also contacted Seaboard who also confirmed TT supply but not offer to add PME.

 

[bertt]

Hi,
Thanks about picture.
I still can’t see the cable body(insulation) but you can check the cable if it is armoured one or not with a magnet.
Put the magnet along the outer cable insulation jacket (exterior and before cable IN) and power off.
2nd option is to check the supply distribution details paper(landlord).Thank you.
I look forward hearing from you.

Bertt.

 

[Knobhead]

What difference does it make if it's armoured. The lead sheath is used for the earth conection.

 

[wildgoose]

Can't he say that it has a TT system and the Electrician is saying the area has poor unstable earthing and for safety reasons please would the DNO provide him with a TNCS earth.

They will probably do it for free anyway - had 3 instances of this over last 18months. The last one, the DNO dug out the old cable and put in a new one with TNCS. All free of charge - very impressed!!