Megger 1553 error, what's the problem?

[VoltzElectrical]

Testing a lighting circuit today in a house. R1 R2 fluctuating readings, so tighten up earths in ceiling rose terminal and get a steady 0.36 ohms.

Power up and on no trip setting (RCBO) the meter gets half way through the test then bleeps and says ERR.

I'm at a loss now, any ideas people?

Thanks in advance.

Oh, and I checked the manual but no clue there. And if there was no earth, the test wouldn't even have started.

One, thing, the lamps were left in, but would that make a difference?

 

[Sintra]

Has one of your leads has lost contact during the test?

 

[GLENNSPARK]

Testing a lighting circuit today in a house. R1 R2 fluctuating readings, so tighten up earths in ceiling rose terminal and get a steady 0.36 ohms.

Power up and on no trip setting (RCBO) the meter gets half way through the test then bleeps and says ERR.

I'm at a loss now, any ideas people?

Thanks in advance.

Oh, and I checked the manual but no clue there. And if there was no earth, the test wouldn't even have started.

One, thing, the lamps were left in, but would that make a difference?

did you not bother trying it on an outlet?
see if you get the same nonsense?

 

[VoltzElectrical]

Sintra, I performed the test many times, and even changed probes as that was my first thought. Pretty confident I got good contact.

By the way, this also happened on the other lighting circuit too.

Glenn, I'm not sure what you mean by 'not bother to test at another outlet? Do you mean a switch?

 

[GLENNSPARK]

Sintra, I performed the test many times, and even changed probes as that was my first thought. Pretty confident I got good contact.

By the way, this also happened on the other lighting circuit too.

Glenn, I'm not sure what you mean by 'not bother to test at another outlet? Do you mean a switch?

no.
verify the instrument is working by doing a Zs at a socket outlet...

 

[VoltzElectrical]

I did loads of Zs values at all the socket outlets I wired. So the meter is working ok, that's why I posted this thread, as suddenly it's playing up on the lighting circuit and i don't know why.

 

[SPARTYKUS]

Batteries okay?

 

[skydog23]

Yea, batteries ? If they are in good condition,
May be worth trying linking at the at the board then doing R1+R2 and adding to Ze.
Sometimes no trip functions give spurious reading as they "tickle" the RCD so as not to trip.

 

[VoltzElectrical]

Yup, new batteries.

Basically, testing whole house, problem only with lighting circuits. Lamps in causing problems? I've never come across anything like this other that has already been suggested such as suddenly breaking contact during the test. That was my first thought and I made all effort to overcome this possibility.

Seems as if I have overlooked something.

 

[VoltzElectrical]

Yea, batteries ? If they are in good condition,
May be worth trying linking at the at the board then doing R1+R2 and adding to Ze.
Sometimes no trip functions give spurious reading as they "tickle" the RCD so as not to trip.

appreciate what you're saying, but why should I get readings on multiple socket circuits, then switch to lighting circuits and suddenly get problems?

 

[skydog23]

Have you a wander lead ?
Measure R1, then measure R2 separately and see if there are any discrepancies between the two readings. May find it's only on one of the conductors.

 

[sparkdog]

I have had a very high Zs with LED lamps in when the R1+R2 was fine.I concluded they must be emitting some noise or waveform.That was with a Megger LTW315.

 

[skydog23]

May have a bit of earth leakage ? Or an interconnection somewhere on the circuit.
Try a volt meter on low volts and see if there's a small voltage present.

 

[Sintra]

Is the code just err or err79? The latter is to do with electrical noise or harmonics on the circuit. This can happen when there are high frequency fittings or dimable transformers plus noise from other circuits on the cu. I would suggest that you isolate all other circuits and try a single lighting circuit.

 

[GLENNSPARK]

Yea, batteries ? If they are in good condition,
May be worth trying linking at the at the board then doing R1+R2 and adding to Ze.
Sometimes no trip functions give spurious reading as they "tickle" the RCD so as not to trip.

eh?...
twaddle here.
low current loop works as just that....15mA...so as not to trip the RCD.
before this there was D-loc...this worked by injecting a shot of DC into the RCD before sending through the measuring current...so as to `freeze` the RCD....ineffective on modern RCDs...

 

[skydog23]

lean something new everyday, thanks for that
I just rather the adding the R1+R2 to the Ze. Ive never been a fan of trip lock type of functions personally. Cold/dead testing circuits individually first can elevate errors if some of the circuits are energised.

 

[GLENNSPARK]

lean something new everyday, thanks for that
I just rather the adding the R1+R2 to the Ze. Ive never been a fan of trip lock type of functions personally. Cold/dead testing circuits individually first can elevate errors if some of the circuits are energised.

dont understand what you are getting at here.
i think you need to go look at the sequence of tests before posting anything else...

 

[skydog23]

The op is powering up the circuit and testing with the trip function.
He's done his R1,R2.
And he's testing with trip lock now, and getting err,
This is a live test,
I'm not sure if all circuits are on or just the lighting.
People connect all sorts of things to all sorts of circuits, before we get involved with trying to sort out issues. Once live they can play havoc to other circuits. Why would a lighting circuit be any different ?
There's not enough information here for me to give a true diagnosis, just throwing some ideas into post.
I'm not wanting this post end up straying from the original problem into a bicker between two other members,
Just contribute some knowledge instead of picking people up on protocol.
Would you pick members up on spelling if the post were educational ?

 

[VoltzElectrical]

I'm thinking it's noise on the circuit somewhere, all other circuits on, smoke detectors and lamps on the circuit being tested.

Think I will google it or call megger next.

Thanks guys.

 

[Jdsparky]

It is 'noise' on the circuit as I had it a while back a couple of times, once on a lighting circuit with a dimmer on it and once on a boiler circuit, I think I linked through the dimmer and it gave me a reading then, the boiler I was going back next day anyway so tried again and it gave me a reading that time although I had already written down calculation value anyway.