Insulation Resistance

[Pits]

Have just installed 20 external LED spike lights that the client has supplied. All wiring is SWA and on an 10a 30ma RCBO. All was well for a while!

Called back at tripping occurring. Found that the Gardener damaged the SWA and a flex from wiska box to fitting. We returned to repair but after a few hours breaker tripped again and so it continued.

Returned after a rethink. Tested fittings and found insulation resistance on the flexes varied from poor to very poor. Stripped on of the flexes so just single insulted cores and resistance excellent as you would expect (seeing as air has a high resistance)

Anyone had anything like this before?

 

[Marvo]

When you got the poor IR reading on the flex itself was it disconnected at both ends? What test voltage were you using and what was the actual IR reading you got?

 

[Blue Duck]

Yes lots! in pond pumps mainly.

Flex exposed to water / moisture will have a poopty IR after sometime due to moisture getting into the outer sheathing (nothing lasts forever) try a better quality flex

like zis

http://www.elandcables.com/electricalcable/rubberflexiblecable/cable24/h07rn-f-cable-to-bs7919.html

 

[SLIPSHOD & SLAPDASH]

I have just had a very good look through BS7671 and the link you supplied  but cant find any reference to poopty  :innocent

 

[Pits]

Both ends of flex disconnected yes.

 

[Marvo]

IR readings and test voltage?

 

[Blue Duck]

I have just had a very good look through BS7671 and the link you supplied but cant find any reference to poopty :innocent

Its in definitions well in mine at least :slap

 

[SPECIAL LOCATION]

Have just installed 20 external LED spike lights that the client has supplied. All wiring is SWA and on an 10a 30ma RCBO. All was well for a while!

Called back at tripping occurring. Found that the Gardener damaged the SWA and a flex from wiska box to fitting. We returned to repair but after a few hours breaker tripped again and so it continued.

Returned after a rethink. Tested fittings and found insulation resistance on the flexes varied from poor to very poor. Stripped on of the flexes so just single insulted cores and resistance excellent as you would expect (seeing as air has a high resistance)

Anyone had anything like this before?

Not exactly sure what the question is you are asking...??

is it either....

1/ Has anyone ever seen a cable damaged by a gardener ?

or..

2/ Has anyone ever seen an IR tester that can show levels low enough that cause a 30ma RCD to trip? 

i.e. give test results in Kilohm's not Megohms?

most IR testers I have seen give Megohm readings to two decimal places...

e.g.  0.00Meg..    (don't forget 1Megohm = 1,000,000ohms)

and   9.999kilohm's  (or 9,999ohms)   would show as 0.00Meg

BUT  9000Ohms is to high to cause a 30ma RCD to trip!

230v / 30ma = 7666.66Ohms  or 7.66K

3/ So is the question has anyone ever come across someone not to clear about the actual test results they are getting?

or

4/ Has anyone ever seen someone not do the dead tests on the cable first before enegising it...

as surely if the cable had been correctly tested you wouldn't have your "low" readings...?

(What are the actual readings of the tests you have taken?? )

If its one of those four questions then my answers would be:-

1/ yes

2/ no, to read levels this low I use a low ohms continuity scale on a suitable tester.  

3/ yes

4/ yes

Unless its a different question and you can provide a bit more info......

opcorn

 

[NozSpark]

Maybe the flex was unsuitable for its location and has absorbed water?

 

[SPECIAL LOCATION]

Maybe the flex was unsuitable for its location and has absorbed water?

ah... yes option 5...

5/ Has anyone ever seen someone use the wrong materials for a job, not taking into account external influences...

answer...

Yes!

 

[ProDave]

Is this flex something you supplied?  OR was it supplied with the lights possibly pre attached to them?

 

[Steve3948]

We have found external spike lights that pull moisture up through the flex and gland causing condensation in the fitting that builds up over time.

This country is not designed for the imported so called garden lights if you ask me.

We now fit Hunza lights which have worked much better, but still no faith in UK garden lighting products.

 

[sprocketflup]

I have just had a very good look through BS7671 and the link you supplied  but cant find any reference to poopty  :innocent

it was the single insulted cores that made me laugh

 

[Pits]

Thanks to all for the comments.

 

[kme]

If your glands cause sweaty boxes, may I suggest the Wiska variant?

http://www.wiska.co.uk/uk/288,ventgland.html