Zs Testing

[claret73]

Have been looking at NICEIC Videos on the Learning Lounge over the weekend and when Tony talks about testing Zs on a radial circuit, he says you can't (or shouldn't) for fear of breaking EAWR??

Now I've always done Zs on Live circuits...

Should I be doing Calculation only from Ze & R1+R2?
What does everybody else do or think of this?...

 

[acat]

Perhaps he has re written BS7671 Appx 14 states relevant circuit nothing about banning radial circuits and as a Zs can only be done on a live circuit page 87 of OSG. Does he offer an alternative live test.


Chris

 

[Amp David]

He rants on regarding the EAWR stating you shouldn't work on anything live. Think its tosh personally

 

[Des 56]

Is that thee Tony Cable,the defender of the QS system

Perhaps where they are coming from is I believe, the EWR permits working live only when it is absolutely necessary, so if an alternative method of obtaining Zs is available,then that should be the prefered method Ze +( R1+R2)

He has to stick with the oficial line,but in reality, practicality overcomes some dubious H+S advise in my opinion,

If it is he,then safety advise off him would be better spent re organising his organisation so that the H+S issues of Qualifying supervisors signing off untrained /unskilled work can be done away with

 

[claret73]

Yes! It is the 'TC'...

I had to laugh a bit as on here somebody said it's like he's in charge of an Orchestra with his swinging arms...
However, not to poke fun as I do find the Videos useful, just that conflicting advice is not so...
Therefore if I do have Ze & R1+R2 is it against best working practice in people's eyes to not do live Zs on Radials and calculate as per the formula? Seems an easy route, less hassle than removing fittings & accessories. Or do you all prefer to know a true tested Zs reading?
Thanks

 

[Graeme Harrold]

Contentious area. When I did 2391 last year they did hammer on about not working live, however testing is a seperate issue as you should be using kit with GS38 test probes e.g. correct tip protrusion and fused leads.

There are plenty of gadgets that make it all safer for socket outlets and lamp holders.

I can see some of the dangers of testing on a socket as Ive seen plenty where cables pop out when the front is removed.

Anyhoo, all of the live stuff should be IP2x protected

 

[claret73]

This is the problem all over though isn't it? Or seems that way as a retraining Guy...
Too many grey areas, differing viewpoints or contentious points that sway 50/50...

Why can't we have Black & White when there is so much banging on about dangers of electricity & signing your name with potential court appearances if anything untoward happened...

 

[andyb]

Where's the grey area?

If you are testing a radial circuit with socket outlets just plug your tester in, no need to drop live sockets.
Lighting circuits with class 1 fittings can be tested with an adaptor, again no need to expose live parts.
Other circuits where the above is not possible you can calculate Zs.

EAW does not strictly forbid working on live circuits, as Des says, you should only do so when absoutly necessary. So where it is not possible to test without exposing live parts, calculate.

 

[claret73]

I wasn't being specific to testing when I said 'Grey area'...

& Yes, I test Lighting points with an adaptor & Socket outlets with a Socket adaptor from MFT...didn't specify sockets as know they can be radials, sorry...

But your response clears up my original post.