Guess the Fault Time!!!!

[oharaf]

Okay, carrying out a PIR this last week.

Begin the Upstairs lighting circuit.

Continuity (R1 + R2) fine.

Move to IR, reading dancing around the 2.3MOhms mark.

So thinking mmm, possible stuffed cable.

Carrout a continuity between Phase and Neutral (at the CU)

The meter is making and breaking continuously with no time for a value to register.

Q. What was causing this??

 

[ColJack]

neon in a switch somewhere?

low energy lamps in and a switch on somewhere?

electronis dimmer switch left on somewhere?

 

[chivers67]

TV antenna booster still connected in the loft of the light circuit??

 

[GaryMo]

Is that between line and neutral? If so, you're a brave man putting 500v between line and neutral on a circuit you don't know. There could be anything connected which is just waiting to be damaged.

It's easier to explain the potential problems to the person ordering the PIR and ask them if they want that particular test completing though any damage will be their problem. If they decline (more often than not they will) you can then agree this limitation and test IR between L+N to E only.

 

[sparkyspike]

Edit: Too slow again

 

[oharaf]

I had been round the property with the client checking that every single Item had been removed from the circuits.

All plugs, bulbs, motors etc etc.

By the way I always do first IR at 250v just incase.

Anyway, back to the guess the fault!!!!

 

[GaryMo]

When measuring continuity with the meter bouncing all over the place is sometimes the result of voltage and the meter not liking it.

 

[securespark]

Some kind of intermittent short?

 

[ericmark]

Last time I had that the foreman had sent one spark to one end of the cable to repair a light and another spark to other end to find out why the earth leakage trip was tripping (It had not tripped it had been switched off) and needle moved as first spark received the shock. Who then nearly got sacked for his manor in reporting to foreman he's thoughts on the matter.
Anywhere near? It was locked off standard practice when fault reported which may be cable.

 

[il78]

You had a twitch and you kept missing with the leads...

At a guess a water leak somewhere or a rodent chewing through the cable as you were testing...

 

[mattylad]

Solar panels on the roof still connected & clouds passing over....

 

[jockspark]

hands still shaking from the church heating you blew up
changing the programmer

 

[Spark123]

Shared neutral, or a phase and neutral reversal somewhere on the circuit??
Was the link still in place for the R1+R2 and main switch closed when the reading was bouncing?

 

[oharaf]

No Circuits energised, entire installation isolated

The church heating is fixed 40 years old contactor that had been 'fiddled' with at some point!!!

Now this idea of water is getting close, but where do you think it was???

 

[oharaf]

By the way it is the constant 'making and breaking' that made the dawn rise for me.

The shared neutral was the fault i dealt with prior to this one!!