ZS

[thomo27]

A friend of mine is NICEIC registered and recently had his visit - he was advised that ZS tests other than on socket outlets are to be retrieved by calculation rather than live testing as they want to do as little live testing as possible

What are your thoughts on this ?

It is also the NICEIC inspection and testing DVD

 

[Taylortwocities]

Its fair enough. The Ze value is usually done by measurement (=live)

Their approach does also mean that folk have to do R1+R2 measurements - not a bad thing either.

In these days of RCDs on all circuits I have found the "No Trip" results from some testers are not accurate.

I'm OK with that, but then I'm not a Smashy & Niceicey member so they can dictate and DVD all they like.

 

[Lectrician]

It has been this way for years.

You have to do an R1+R2 anyway to prove it is safe to do live tests, so why not just calc anyway.

 

[fattony]

I've always done r1+r2 and measured zs but I can see their point

 

[Taylortwocities]

r1 + r2 or R1 + R2?

 

[thomo27]

r1 + r2 or R1 + R2?

I use the terms little r1 and big R1 when talking about testing Ring Finals and the lads as work think I'm mad....

Im doing the 2391 at the mo and thats how it is referred to by the tutor

r1+rn / 4 = R1+RN

 

[Taylortwocities]

Stick to it. You are on the path of righteousness

 

[sparkybird]

yes I do this now- much safer than struggling on top of a ladder, getting good connection with all three leads and THEN trying the press the test button!!
SB

 

[fattony]

its just an r and if I was writing something professional I might have bothered to type R.

You are correct it should be R1 + R2

 

[securespark]

Let me put the cat among the pigeons a bit...

My tutor at college thought that live testing was the way to go. Do away with r1r2 tests and just do an EFLI test at every point.

That way you confirm satisfactory r1r2 and EFLI and polarity all in one press of a button.

Controversial, I know...

[Dives for cover under desk]

 

[Lectrician]

Let me put the cat among the pigeons a bit...

My tutor at college thought that live testing was the way to go. Do away with r1r2 tests and just do an EFLI test at every point.

That way you confirm satisfactory r1r2 and EFLI and polarity all in one press of a button.

Controversial, I know...

[Dives for cover under desk]

You can only do that when certing a PIR - because the site is already live. On a new install/new circuit, you have to do all the dead tests first to ensure it is safe to perfrom live tests, you have therefore done the R1+R2 (or r1 and r2 for a ring), and using these and the Ze, you have the Zs. No point then doing the Zs again.

I am always amazed at how many certs I see where they have done (or made up ) both tests, noticable because the maths does not work correctly.

 

[NotHimAgain]

Let me put the cat among the pigeons a bit...

My tutor at college thought that live testing was the way to go. Do away with r1r2 tests and just do an EFLI test at every point.

That way you confirm satisfactory r1r2 and EFLI and polarity all in one press of a button.

Controversial, I know...

[Dives for cover under desk]

Do you call that putting the cat among the pigeons

You don't do it like that - you do it like this -

First please find a regulation in the national standard BS 7671, or its parent IEC and CENELEC documents that requires that I measure R1 + R2 on initial verification or a PIR.

Next tell me why I can't use my bell and battery to prove continuity (612.2.1) - before you leap I have all of the sections of BS 61557 and I have read them. My bell and battery exceeds the voltage and short-circuit current requirements given in 612.2.1 (note: appendix 6 is Informative not Normative.)

Then read 612.9 and note that measurement is a permitted method of determining Zs.

Remember GN 3 is just guidance nothing more.

Now that is putting the cat among the pigeons

 

[oharaf]

I just love to Test!!!!

The problem with calcs is that figures lokk 'to perfect'!!!

We all know that when we test and perform cals on the figures to check they are never that accurate.

The thing with testing is, doing the whole lot BTW, is you test and record and that is the figures obtained on the day!!!

By calc it means that 'the circuits should be like this' however if something went tits up and you landed in court and you were asked 'how do you know it was safe' and all you can really do is say I carried out a couple of tests then worked the rest out.

To me this would leave ourselves WIDE open.

Yes we all get to the end of the day sometimes and do a quick Zs and RCD and go and calc the rest butone day......


The regs do refer to the process as 'Inspection & Testing' testing means just that to me