Yesterdays little heart beat skip

[Toonlad]

Called around to recce a job coming up soon for a builder. Looks around house (unoccupied - nice one) things looking good for the extension. Takes a look at at existing bonding cu and supply etc. Noted the clamp on the lead covered incomer, thought thats naughty, and it was 10mm. then followed it up the cu and noticed its chopped. Ahhhh no earth, runs back to van gets tester out.

Then I go to take the lid off and notice 2 rcds, eyesight a bit sh1te but it was 100ma and 30 ma,, ok all the signs now point to TT. checks these 2 x 10mm one was to gas and water continuous bond. the other to a spike. Result Get up ye dancer.

Ze was at 0.18ohms happy with that, and better when it goes to 16mm.

But on a side note why was there a clamp on the supply incomer, I did actually test the lead sheath also to confirm earth path, but there was none. I understand why it was chopped due to twig in garage floor.

But why the use of the clamp in this instance, someone just trying to bond the cable also ??

 

[telectrix]

around here there are quite a few houses built in the 70's with TN-S clamps on incoming sheath and a rod. could be the same, but you have a cable cut.

 

[Toonlad]

yer the 10mm from the clamp to cu was cut just below entry to cu. It seems to me by my test results the sheath of the cable is not earthed at transfomer side, its dead. If it was TN-S and the twig was used to enhance the Ze i could understand that more.

 

[telectrix]

try an IR test @250V between bonding cable and lead sheath. that should confirm.

 

[Toonlad]

Not quite sure what you are thinking Tel,, its probably my post misleading you slightly.

If you are on about the bond to the clamp on the lead sheath, this is a bout 18 inches away and i can physically see end to end. I did a Ze direct contact to lead sheath with my test lead.

Cheers

 

[telectrix]

did you get any reading at all?

 

[Toonlad]

No reading with direct connection to sheath of cable.

Ive got nowt on this afternoon, think i will borrow my mates tester also, and compare the Ze.com. Take some pics also.

 

[power ranger]

I'm thinking breakdown of suppliers TNS earth at some time in the past, DNO have refused to reinstate the earth and so a sparky came in and just converted to TT and they have just left the earthing conductor in place and just cut it below CU.

 

[Toonlad]

Probably the more feasable answer. I think i will knock on a neighbours door and try and see what arrangement they have. I have an acceptable Ze. But i am now more curious to why it is this way. LOL

 

[power ranger]

Probably the more feasable answer. I think i will knock on a neighbours door and try and see what arrangement they have. I have an acceptable Ze. But i am now more curious to why it is this way. LOL

I think you are worrying too much!

Probably no need to speak to neighbour, but have you done test with main switch open and earthing conductor taken out of the MET to confirm Ra through your rod?

 

[Toonlad]

I think you are worrying too much!

Probably no need to speak to neighbour, but have you done test with main switch open and earthing conductor taken out of the MET to confirm Ra through your rod?

not worrying at all like i said ze is acceptable. Yes i do test correctly ie switch in open position.

The problem i have is curiosity and the desire to know why things break or interprid why things are done in a particular way. Even after 30 yrs of sparking i still ask questions like an apprentice; and i still enthuse for knowledge in my chosen trade.

 

[GLENNSPARK]

Called around to recce a job coming up soon for a builder. Looks around house (unoccupied - nice one) things looking good for the extension. Takes a look at at existing bonding cu and supply etc. Noted the clamp on the lead covered incomer, thought thats naughty, and it was 10mm. then followed it up the cu and noticed its chopped. Ahhhh no earth, runs back to van gets tester out.

Then I go to take the lid off and notice 2 rcds, eyesight a bit sh1te but it was 100ma and 30 ma,, ok all the signs now point to TT. checks these 2 x 10mm one was to gas and water continuous bond. the other to a spike. Result Get up ye dancer.

Ze was at 0.18ohms happy with that, and better when it goes to 16mm.

But on a side note why was there a clamp on the supply incomer, I did actually test the lead sheath also to confirm earth path, but there was none. I understand why it was chopped due to twig in garage floor.

But why the use of the clamp in this instance, someone just trying to bond the cable also ??

do you think this will make much difference on a TT?

 

[telectrix]

something smells wrong here. i can't see a Ze of 0.18 on a twig, TBH, even if eng54 istalled it. LOL.

 

[GLENNSPARK]

something smells wrong here. i can't see a Ze of 0.18 on a twig, TBH, even if eng54 istalled it. LOL.

it`l be parallel paths here Tel...

 

[power ranger]

something smells wrong here. i can't see a Ze of 0.18 on a twig, TBH, even if eng54 istalled it. LOL.

it`l be parallel paths here Tel...

Thats why I asked Toonlad if he had taken the earthing conductor out of the MET.

He said he opened the main switch but not answered fully my question.

 

[telectrix]

must be relying on water/gas pipes to get that low.

- - - Updated - - -

it`l be parallel paths here Tel...

parallel paths should be dissed to measure Ze.

 

[GLENNSPARK]

must be relying on water/gas pipes to get that low.

- - - Updated - - -



parallel paths should be dissed to measure Ze.[/QUOTE]indeed....
makes you wonder then....

 

[Toonlad]

do you think this will make much difference on a TT?

Not over the distance of 2 mtrs no. However there is nothing wrong in striving to get the best reading possible on a TT. Hence more arguments on here accepting anything under 200ohms is fine.

something smells wrong here. i can't see a Ze of 0.18 on a twig, TBH, even if eng54 istalled it. LOL.

Nothing smelly here lol,why not get a good reading like that ive had a few over the years, it is what it is. Been back this afternoon, checked with another mft, and it was 0.19ohms.

it`l be parallel paths here Tel...

No parrallel paths all bonding conductors disconnected at time of testing

Thats why I asked Toonlad if he had taken the earthing conductor out of the MET.
He said he opened the main switch but not answered fully my question.

Like i said i tested it correctly. Granted i did not quote that i had removed the earth from the MET, but testing correctly is removing it,and opening the switch.


I was back this afternoon, the reading is correct, No parrallel paths the neighbours are on TT there spikes in the garage too.

so can we get back to why was there a clamp on the incomer when there is no earth path on it. The best answer has been power ranger thus far.

 

[GLENNSPARK]

Not over the distance of 2 mtrs no. However there is nothing wrong in striving to get the best reading possible on a TT. Hence more arguments on here accepting anything under 200ohms is fine.


Nothing smelly here lol,why not get a good reading like that ive had a few over the years, it is what it is. Been back this afternoon, checked with another mft, and it was 0.19ohms.



No parrallel paths all bonding conductors disconnected at time of testing



Like i said i tested it correctly. Granted i did not quote that i had removed the earth from the MET, but testing correctly is removing it,and opening the switch.


I was back this afternoon, the reading is correct, No parrallel paths the neighbours are on TT there spikes in the garage too.

so can we get back to why was there a clamp on the incomer when there is no earth path on it. The best answer has been power ranger thus far.

View attachment 18586

couldn`t agree with you more....depth of rod/s & suitable siting would be the key here....

 

[markc123]

I think you are worrying too much!

Probably no need to speak to neighbour, but have you done test with main switch open and earthing conductor taken out of the MET to confirm Ra through your rod?

Wrong.

When the house is unoccupied the neighbour provides the brew labour :lol: