Fault on ring but ok as 2 radials?

[VWFAN]

Hi, iam wondering if anyone can give me some advice, i have a fault on a ring where there is short between live - earth on the IR test, but when split into 2 x radials there is no fault. When as 2 x radials all results are >999 but when its then connected as a ring the readings are between 802 and upto 840, there is 11 legs on the ring and all have been sripped down and each leg tested individually and all are fine, i even done and IR test on all the sockets just on the off chance.

The ring is a complete ring with no spurs etc in a new build house less than 5 years old, ive been told there have been 4 sparks before me but nothing been done.

Iam at a loss here and have spent too many hours on it already, apart from a rewire iam at a loss, even if i was to rewire there is no specific leg that is faulty when tested individualy.

Any advice would be much appriciated.

 

[Deleted member 9648]

Are you saying between 802 and 840 megohms??.....whats wrong with that?.....how much time in total have you spent tracing this 'fault'?

 

[Octopus]

Do you know the minimum you have to achieve?

 

[telectrix]

as above. if readings are 800+ meg., what's the problem? a bit of warm breath on the crocs will give worse than that.

 

[hospital]

even I knew that and I work for the NHS

 

[KFH]

When you split it into two radials does it matter where the split is made to get rid of the "short"? If so it may be the fitting where the join is made. When you do the testing are all the accessories in place? It could be fitting them causes the "short". If you break the ring in a different place with all the accessories fitted does the result change?

You can make it two radials but assuming 2.5mm cable you would need to put 20A MCB as protection for each radial, I am assuming that putting two radials onto one 20A may be excessive but you would need to work out the max load.

 

[Guest123]

What fault did the customer report first of all??? RCD tripping etc???

 

[telectrix]

or swap your tester for one that only reads to 99Megohms

 

[Marvo]

Are you looking for an RCD tripping fault? Tracking down an IR fault of 802 and 840 megohms (I'm assuming the test result was from a mega tester) is great practice if you've got lots of spare time but it's not going to achieve anything.

 

[Octopus]

Heaven knows what he'll do when he starts doingwork on a 1950's or earlier house!

 

[telectrix]

usually get good IR readings with singles in wooden channelling

 

[Deleted member 9648]

usually get good IR readings with singles in wooden channelling

That takes me back.....havent seen one of those in years,always seemed tragic ripping it out,that level of craftsmanship is long gone.

 

[Specialist]

This has just got to be a wind up, over 800 Meg on a Ring ? Don't think i'd be wasting my time looking for a Fault.

 

[Engineer54]

Your all talking to yourselves here... VWFAN hasn't been around to answer any queries or give any further information since his OP!! So we don't know if he's talking about 800 ohms, 800 Kohms, or 800 Mohms!!

 

[KFH]

I must admit I assumed the readings were Ohms. If MOhms what a waste of time. Please tell us it was not 800MOhm.