High earth loop readings

[duxter121]

Hope someone can help, I am an industrial biased electrician & a friend has asked me to check an outside tap on one of his houses where the tennant keeps getting a belt off the tap, the loop test at the board shown up 17.8ohms & was registered as dangerous on the tester (A Metrel tester)...
The supply I think...is a TT system or a TN-S, not got a regs book with me & not 100% on supply systems (which i'm reading up on now)..bad I know
Anyway, there is 2 cables run down the outside of the house & what looks like the earth is tapped off the neutral about 1 METER before the cut-out & disappears down the wall & under the decking....I do know that he had a dodgy spark do some work on it for him years ago & I have done some reading up on possibilities of what it could be & the only one I can think is that they may have used the other services, gas & water to bond the house
There is no earth at the cut-out or electric meter....

 

[Marvo]

Some photos might help if you can attach a few. If you're not familiar with earthing arrangements then you may be well to seek assistance from someone who is.

 

[duxter121]

Didnt get chance to take any at the time, but think it desperately needs looking at, I work away a lot & havent really got time to look at it, thanks for the reply my good man..!!

 

[trev]

Have you checked with the DNO to see if they have a record of what the earthing system is, it could be a TT in which case 17.8 ohms acceptable

 

[tony mc]

You need to ID the earthing arrangement at 17.8 ohms on a TT is acceptable.

However the issue re the water pipe being live needs urgent attention!

IMO your friend needs to call out a spark who can investigate any issues that the dodgy !!!!!spark!!! has left and make them safe ASAP.

Welcome to the forum!!

 

[duxter121]

Who is the DNO matey...?? So what would explain the shocks she keeps getting off the outside tap...could it be that its been equip bonded to the mains...?? its an old 15th or 16th edition board with type B MCB's...thanks for the reply too ;-)

 

[trev]

Sorry mate I easily slip into acronym mode. Distribution Network Operator
The reason for the pipework being live could be a few things, It's a rough way to do it but you could try turning off ther MCBs one by one and hopefully you could identify which circuit is faulted then test the bejaysus out of it to find the problem but it needs to be bottomed out pretty damn quick I'd say

 

[duxter121]

its not always live, it wasnt live while i was there & even with running water, did the loop test & wasn't happy with the result hence me panicking a bit after trying to tell the tennant not to worry too much...or should I have told her to worry, I am currently trying to get in contact with the houseowner & doesnt seem to be picking up ...hmm, cheers tony

 

[Des 56]

Have you checked with the DNO to see if they have a record of what the earthing system is, it could be a TT in which case 17.8 ohms acceptable

Is an RCD present ?

 

[duxter121]

cheers trev & tony... I hate to leave things I dont like & not being that fluent in domestic installations, earthing arrangements etc...(bad I know) I'm not sure what to look for ie, test results from the regs (lent my copy out anyway..!!!)
I am more industrial & commercial....hence me not doing houses...i'm not built for it anyway...ha

 

[duxter121]

None whatsoever Des....

 

[trev]

Hmmm...faulty appliance leaking maybe?
Either way it's a testing job mate

 

[duxter121]

No there is no RCD at all...just MCB's Des

 

[Des 56]

No there is no RCD at all...just MCB's Des

Then they have problems indeed and an installation that could cause them harm,thats assuming you are correct that the installation is TT
Fit an Rcd for them as a quick fix temporary measure

 

[richy3333]

I think the OP described the earthing arrangement in his first post by the description?...

If in doubt a Ze test will confirm the earthing?

 

[TaffyDuck]

Dont forget static! If the outside tap appears to be only live sometimes this could also be a charged person. nylon carpets and socks inside straight into nice rubber wellies then outside into the garden and its not unusual that you are carrying a static charge yourself. Touching a well earthed outside tap will discharge the static you are carrying down the pipe or through the bond to earth and give the same sensation as a shock even though its the electricity is travelling in the opposite direction.

Not saying that it shouldn`t be checked, far from it, and an RCD install is very sensible advice, just saying that occasionally there can be no fault present.

 

[GLENNSPARK]

isolate the supply and remove bonding clamp (if any) from the pipework in question......then IR test at 500V DC between each final circuit in turn and the affected pipework.....if theres a breakdown in insulation..should find it......

 

[GLENNSPARK]

as the others have already said here.....theres a potentially dangerous situation here where if on a TT theres no RCD..often the only means of fault protection you have for rods......and you cant leave voltages sitting on pipework....even if only intermittent.......

 

[GT1]

As others have saidit needs a thorough investigation.. Good chance its an appliance somewhere gone to fault.
Last time I had a live water system on a house it was the garden pond UV light..!!