Hmmmm not sure that's right?...

[lawrence0117]

Evening folks, couldn't change this sparks mind! It was an old boy, I started questioning it but rather than cause a scene I just pacified him and walked away, not my name on the cert! Working in a pub with him and asked what he was testing, turns out it was Zs of lighting circuits by having his socket tester probes plugged into a extension lead on a local socket circuit but the earth lead removed from his meter and instead he had his earth probe lead connected and probed onto the cpc at various points on the lighting circuit to get a Zs. I've never seen that before, doesn't seem right at all!??!! The meter is testing down the socket circuit and back along the cpc of lights, and he said "well, that's what I need to know, just the earth return path" anyone else seen people do this? looks like he was just being lazy and not wanting to remove covers etc!

 

[telectrix]

seems like all he was doing was provint that the lights had cpc. no way could he get an accurate Zs doing it that way. lazy bugger.

 

[Deleted member 26818]

My understanding, is that the Zs include the supply side, not just the return path.
As he was not measuring the supply side of the lighting circuit, then I cannot see what value his tests woul provide?

 

[Guest77]

Evening folks, couldn't change this sparks mind! It was an old boy, I started questioning it but rather than cause a scene I just pacified him and walked away, not my name on the cert! Working in a pub with him and asked what he was testing, turns out it was Zs of lighting circuits by having his socket tester probes plugged into a extension lead on a local socket circuit but the earth lead removed from his meter and instead he had his earth probe lead connected and probed onto the cpc at various points on the lighting circuit to get a Zs. I've never seen that before, doesn't seem right at all!??!! The meter is testing down the socket circuit and back along the cpc of lights, and he said "well, that's what I need to know, just the earth return path" anyone else seen people do this? looks like he was just being lazy and not wanting to remove covers etc!

It was quite common once to use the flying earth lead on a MFT to test loop impedance, he is old school and has not been told it is now not allowed lol

 

[Gavin A]

couldn't he have calculated the actual Zs of the lighting circuit if he already knew the Ze and the Zs of the socket circuit from that point / Zs of the socket circuit plus extension?

 

[ImpededLoop]

couldn't he have calculated the actual Zs of the lighting circuit if he already knew the Ze and the Zs of the socket circuit from that point / Zs of the socket circuit plus extension?

No he couldn't as he wouldn't know the R1 value of the lighting circuit, he's measuring R1 of the socket circuit and R2 of the lighting circuit.

He'd be better off with one of those Kewtech lighting adaptors to measure R1 and R2 of the lighting circuit.

 

[Gavin A]

No he couldn't as he wouldn't know the R1 value of the lighting circuit, he's measuring R1 of the socket circuit and R2 of the lighting circuit.

He'd be better off with one of those Kewtech lighting adaptors to measure R1 and R2 of the lighting circuit.

you're probably right, I've made my head hurt trying to work out if it could be calculated.

 

[trev]

It was quite common once to use the flying earth lead on a MFT to test loop impedance, he is old school and has not been told it is now not allowed lol

Yes it was but at least the L & N leads had to be on the proper terminals. Doing it this guys way is madness and proves nothing except that there is an earth at every fitting.
He's old school because he's never been taught properly.

 

[Guest77]

Yes it was but at least the L & N leads had to be on the proper terminals. Doing it this guys way is madness and proves nothing except that there is an earth at every fitting.
He's old school because he's never been taught properly.

Totally agree, I have seen guys walking around with a MFT plugged into an extension lead and using the flying lead several timess chuckle, certainely not my way but it was the norm at one time.

 

[R G]

I seem to recall . I had an old seaward e/loop tester years ago within a black leather case that had a fixed mains lead with plug top fitted and a earth prod socket for wandering earth lead , that was what we used for testing bonding continuity on sinks and earth terminals at light fittings , if not careful you would leave a burn mark on sinks , as it gave out 20 amp pulse , no way could you use the live on the lighting circuit as it would defo disconnect the fuse ..

I will hunt around I might still have it..

 

[Guest111]

I seem to recall . I had an old seaward e/loop tester years ago within a black leather case that had a fixed mains lead with plug top fitted and a earth prod socket for wandering earth lead , that was what we used for testing bonding continuity on sinks and earth terminals at light fittings , if not careful you would leave a burn mark on sinks , as it gave out 20 amp pulse , no way could you use the live on the lighting circuit as it would defo disconnect the fuse ..

I will hunt around I might still have it..

we used to call it a splash test,I've still got mine in the cupboard.

 

[Rockingit]

OK, it's not correct and I'm therefore not going to defend it, but just thinking it through logically, the reading he'll be getting is R1 of a power circuit, and then the R2 of the lighting one + % of the R2 of the power. So, at least his Zs will be pessimistic.