Discuss Diy tt ?? in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

acvc

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Arms
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OK I'm not very experienced, waiting to register as Competent Person, but I came across this this morning. I was meant to replace some light fittings in the house, and on checking the main earthing and bonding first, this is what I saw, i.e. no main earth conductor only a strange 6mm 6242Y in the earth terminal going to godknowswhere (down under the floor and towards the back of the house), certainly not to the head or supply sheathing. I thought it might be a DIY TT effort but couldn't find the other end of the 6242Y. Bonding was in 6mm from the gas, and water bonding 6mm connected to the gas BS951 clamp. He wasn't happy when I said I wouldn't do the job. I recommended he gets a PIR done to start with, especially as he intends to rent the place out. Ze came out at 707ohms, PFC as less than 1A.
 

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your well out of it. 700ohms! he definately doesnt have an earth ,should be 200 or less but anything over 100 is suspect.
your well on your way to being competant if you turned this one down.
look like it needs a rewire, trouble is he will get someone who doesn't give a monkeys to do it, and some poor sod will have to live there
 
S

Spudnik

Yep, no earth.

I expect the 707 is coming from the gas and water bonds.

Why not just quote to put an earth rod in as an extra?

Agreed, it does probably need a rewire, and quite possibly no cpc at the light fittings, but at least it will be safer.

I wouldnt like to leave it like that!!!
 
It may have been worth checking Zs at a few sockets while you were there. To measure Ze you presumably picked an earth wire from the jumble and measured the resistance to earth of that wire on its own. There may still be other connections to earth, including the bonding. Obviously this would not be sufficient to meet the regs, but it may show that the overall earth impedance is not quite as high as 707 Ohms.
 
S

spark1

I would agree with the recommendation for a P.I.R. and would not carry out any work on the installation until satisfactory rmedial work had been completed......in addition I would follow up with written notice of said Recommendatiion.......If you dont get the work then thats the way it goes but at least your integrity is in tact...there will be another job soon where the client Will take your advice and you will feel good about taking this stance......Some you win Some you lose.................Good luck !
 

acvc

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Arms
  • Thread Starter Thread Starter
  • #6
All I did for the ZE was take everything out of the earthing terminal except for the 6242Y, and measure from the block.

I have emailed the guy and told him to contact his Distributor (Eon) and ask what earthing system they think is present in the property. If TN then please suppyy an appropriate MET fast, if TT then to convert to PME fast.

I did do a few Zs on downstairs ring as well, with everything connected at the board again. Readings came out at 11-12ohms, with PFC 19-20A. Reduced Z i put down to parallel paths .... am i right in thinking this, it seems like a huge reduction from the 707 Ze at earth terminal in c/u. It was a 4-way Wylex with 3063s, added shower output too.
 
E

electro

No because its not a TT install.

How do you know its not a TT?

Regards
 
M

Mac

Looking at the incomer,it is the same as mine and should be TNS.Lead sheathed cable but the clamp is missing.I would phone the DNO up and tell them the clamp is damaged:eek:
 
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S

Spudnik

How do you know its not a TT?

Regards
As above.

TNS supplies are lead sheathed (in older installations) which is what is in the picture, with, what looks like, the main earth hanging down by the side of it.

It should be clamped on the lead sheath with the correct clamp.

Looking at the incomer,it is the same as mine and should be TNCS.Lead sheathed cable but the clamp is missing.I would phone the DNO up and tell them the clamp is damaged:eek:
I think you mean TNS.
 
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E

electro

Hi


[FONT=Arial, sans-serif]You can get a new supply with the same service head as a Tnc-s and still be a TT (Should be Labelled), some times it depends on the use and who the DNO is, although this looks like a domestic property with a missing lead sheath bond, but if you then use a earth spike this becomes a TT [FONT=Arial, sans-serif]installation.[/FONT][/FONT]
[FONT=Arial, sans-serif][/FONT]
[FONT=Arial, sans-serif]Regards
[/FONT]

As above.

TNS supplies are lead sheathed (in older installations) which is what is in the picture, with, what looks like, the main earth hanging down by the side of it.

It should be clamped on the lead sheath with the correct clamp.



I think you mean TNS.

Jason A clamp on a lead sheath is a code 1 as stated by the NICEIC

I think you mean sweated earth to the lead sheath..

Regards
 
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S

Spudnik

Fair enough, but down here with SSE, i have never seen this as you describe.

TT have all been overhead (some converted to TNCS), TNS lead sheathed underground, and TNCS underground with supplied MET.

I think you mean sweated earth to the lead sheath..
Nope.

Most have been a special spring type clamp and some 951 clamps which of course is a no no.

Ill see if i can find a picture.
 
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M

Mac

As above.

TNS supplies are lead sheathed (in older installations) which is what is in the picture, with, what looks like, the main earth hanging down by the side of it.

It should be clamped on the lead sheath with the correct clamp.



I think you mean TNS.
Sorry mate i did:eek:
 
E

electro

[FONT=Arial, sans-serif]Hi[/FONT]

[FONT=Arial, sans-serif]I have had battles all over the country with DNO supplying earths to installations, they do state they have no obligation to supply an earth, that's why they sometimes make you pay £108 ish to re-sweat an earth or upgrade to TNC-S. Sometimes you can prove it has deteriorated other times they say pay the fee or go TT. They see it that you need them, more than they need you...[/FONT]



[FONT=Arial, sans-serif]PS Jason was it a hillman connector you were referring to, are they still fitting those I thought they stop all forms of compressing old lead sheath cables?? [/FONT]


[FONT=Arial, sans-serif]Regards[/FONT]
 
S

Spudnik

[FONT=Arial, sans-serif]Hi[/FONT]

[FONT=Arial, sans-serif]I have had battles all over the country with DNO supplying earths to installations, they do state they have no obligation to supply an earth, that's why they sometimes make you pay £108 ish to re-sweat an earth or upgrade to TNC-S. Sometimes you can prove it has deteriorated other times they say pay the fee or go TT. They see it that you need them, more than they need you...[/FONT]



[FONT=Arial, sans-serif]PS Jason was it a hillman connector you were referring to, are they still fitting those I thought they stop all forms of compressing old lead sheath cables?? [/FONT]


[FONT=Arial, sans-serif]Regards[/FONT]
If the DNO'S supply an earth it is THEIR responsibility to maintain it.

And yes, i think it was a hillman and they dont use lead sheathed cables anymore
 
Like the meter outgoing !
Do you mean the three tails at the cu isolator that have been reduced to a couple of strands apiece to make them fit?!!!!!
 
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