Continuity problem

[ian932]

I was doing a PIR on Friday and had a strange reading on the 2 rings.

The process I go through to make sure everything is switched off / unplugged is check L-N for any resistance then run 250V IR up the L-N to see if there are any neon

 

[Andy™]

most likely something still connected. best for short L-N and test L-N to earth

 

[ian932]

most likely something still connected. best for short L-N and test L-N to earth

Already done and clear to earth, the question is what item of equipment etc could give those kind of un-measurable resistance indications.

 

[Andy™]

could just be that there is a continuity (0.25m), but on continuity, its off teh scale so cant display actual reading, but causes it to display closed circuit

 

[SPECIAL LOCATION]

...So I try IR on each ring @ 250v and get around 0.25Mohm which is what I would expect from a neon.

It does sound very neon'ish???

Any built in kitchen appliances?

Boilers boxed in?

Spurs off to garden shed?

I did have a house with a DP20 switch with neon used as a JB under the lounge floor once!!!

no chance of finding it if something like that?

What about splitting the ring half way round and trying it as two radials, to narrow it down?

 

[Riggy]

Why not discuss limitations with client? i.e. phase/phase IR = LIM, phase/earth = actual reading (you say clear to earth), comment in relevant box. That's the way I'd approach it, nothing to be gained other than personal satisfaction from cracking this one IMHO

 

[ian932]

I did have a house with a DP20 switch with neon used as a JB under the lounge floor once!!!

no chance of finding it if something like that?

I think it may be something like this :_|

What about splitting the ring half way round and trying it as two radials, to narrow it down?

Can do but the house has 45year old wiring and has had so many diy add on's it appears there are some multi socket radials off the rings so its gonna be a marrathon to sort out how the ring is wired.

 

[patspark]

had this before same as you have done ir test at 230v just incase there is something i have missed got l to n reading off the scale thought i had a dead short turned out to be a

small fridge in a copboard in the hall

 

[Apache]

Aerial booster in the loft?

 

[SPECIAL LOCATION]

Aerial booster in the loft?

Think you'd get a lower IR reading with an aerial booster?

But good thinking Applaud SmileyApplaud Smiley

 

[fastham]

That sort of reading i have come across before, 2 things to check for, Surge protection ext lead (customers always forget to unplug em) and last week had an rcd type switched fused spur. (of ring feeding a small waterfall in garden)

When i took off rcd fcu, ring cleared, checked unit on its own, gave reading of 0.2MΩ