high r1+r2 on lighting circuit

[daveb]

Hi all,

Strange one today that i've never seen before - hoping someone else may have seen this...

Wiring an additional outside bulkhead today - couldn't easily get to the last fitting to take a switch wire from there so split the switch wire as close as i could to the fitting and wired in a junction box. Took a spur from the junction box as well as connecting up the other light.

Anyway, came to do the testing and was getting 48 ohms on my R1+R2?? Strange thing is that the loop impedance is fine (1.14 ohms) and the RCD is OK too. There was already an RCD on the circuit before hand.

Has anyone experienced this before? Surely if there was anything untoward then you would expect the earth loop imp to be high?? Im starting to wonder if my tester is playing tricks.

Thanks

 

[telectrix]

i'd be looking at a poor connection of your leads. my MFT (megger 1553) went for calibration and was about to fail. tester said it needed stripping and the internal connections on the 4mm sockets resoldering.

a quick rub with a 3.5mm rethreading tool on the 4mm sockets cured the problem.

 

[sparksburnout]

Dunno. Whats an SVQ 3? Edit - Ah! A scottich Vocational qual. Blimey, almost ready for the umbilical cord to be cut.......Lol, good old Nicola.

 

[daveb]

Dunno. Whats an SVQ 3?

Scottish equivalent of an NVQ level 3

 

[telectrix]

scottish NVQ3?

 

[telectrix]

and what's that got to do with this thread?

 

[daveb]

i'd be looking at a poor connection of your leads. my MFT (megger 1553) went for calibration and was about to fail. tester said it needed stripping and the internal connections on the 4mm sockets resoldering.

a quick rub with a 3.5mm rethreading tool on the 4mm sockets cured the problem.

It's funny, my tester the other day kept coming up with "CON" when i was trying to do an earth loop imp test. Thought i wasnt jamming it into the terminal block properly but i was. The annoying thing is it

i'd be looking at a poor connection of your leads. my MFT (megger 1553) went for calibration and was about to fail. tester said it needed stripping and the internal connections on the 4mm sockets resoldering.

a quick rub with a 3.5mm rethreading tool on the 4mm sockets cured the problem.

its funny - the other day my multi tester wouldnt allow me to do an earth loop imp test, kept coming up with "CON". I thought i maybe wasnt getting a proper connection into the terminal block but then discovered it was throwing a wobbler. Thing is, it was bought new only back in June which wont give me much confidence in Megger if that is the case! I'll get it booked in tomorrow to see.

 

[sparksburnout]

and what's that got to do with this thread?

Ohh spikey. nowt

 

[daveb]

and what's that got to do with this thread?

exactly - ask the guy who asked the question in the first place. He maybe thinks im a cowboy

 

[telectrix]

yeee. haah.

 

[westward10]

If I ever get something like that I try a line/neutral continuity test to see if it the circuit/me/tester.

 

[Wilko]

... Surely if there was anything untoward then you would expect the earth loop imp to be high?? Im starting to wonder if my tester is playing tricks

Yes, something not right the R1 and R2 measurement, as Ze + (R1+R2) is the earth loop impedance(ish). If you used method 1 from GN3 are you sure the temp link went from the correct mcb to the earth bar? Sorry don't mean to be basic, but I'd confirm with another measurement and a lead clean-up as per Tel. Hope that helps

 

[daveb]

Yes, something not right the R1 and R2 measurement, as Ze + (R1+R2) is the earth loop impedance(ish). If you used method 1 from GN3 are you sure the temp link went from the correct mcb to the earth bar? Sorry don't mean to be basic, but I'd confirm with another measurement and a lead clean-up as per Tel. Hope that helps

thanks Wilko - yes, i performed the test twice to make sure.

 

[sparksburnout]

exactly - ask the guy who asked the question in the first place. He maybe thinks im a cowboy

Not with a Sturgeon Valid Qualification surely?

 

[Krispy_88]

It's funny, my tester the other day kept coming up with "CON" when i was trying to do an earth loop imp test. Thought i wasnt jamming it into the terminal block properly but i was. The annoying thing is it


its funny - the other day my multi tester wouldnt allow me to do an earth loop imp test, kept coming up with "CON". I thought i maybe wasnt getting a proper connection into the terminal block but then discovered it was throwing a wobbler. Thing is, it was bought new only back in June which wont give me much confidence in Megger if that is the case! I'll get it booked in tomorrow to see.

In my experience with the Meggars, CON shows up when you are trying to take a loop impedance using two leads, when the set tester is set to three leads. I don't know if you have the same module though, mines a MFT1721

 

[Des 56]

Yet again,murmurings about an MFT code when it just refuses to do its job
Don't use a Mft and never have these meter problems

 

[telectrix]

this one of yours, Des.?

 

[Rpa07]

Is that a wind up Tel?

 

[Des 56]

Is that a wind up Tel?

I can't recognise tels machine,its more advanced than the ones I use,modern rubbish I expect

 

[DPG]

What result do you get if you test with the clips shorted together?