No live testing except where it's a must

[Les Macaulay]

Do you agree that we only should be working dead when establishing the Zs for final circuits other than socket outlet circuits? That is, don't use the line, neutral and earth probes of the E/L tester except for Ze and Ipsc. Simply add R1+R2 to Ze.

 

[Silly Sausage]

No!...

 

[Adam W]

A calculated Zs is only theoretical and can be different from a measured Zs, so IMO Zs should be measured unless it really will be dangerous (eg require dismantling live equipment). You can get ES and BC adaptors for light fittings and putting probes on live FCU terminals is hardly 'dicing with death'.

 

[Sintra]

Absolutely not. Always test Zs on all circuits how else would you know your circuit complies with the values for maximum permitted Zs. Calculations do not allow for high impedances through some MCB's, RCD's etc.

 

[markc123]

Health and Safety gone mad these days, if you follow the book then Les you're probably correct...no live testing where possible. However, have to agree with Archy and Adam on this one...a measured Zs is far better on the cert than a theoretical one IMO. I think it is acceptable to add R1+R2+Ze for every circuit if you want, but i personally prefer a measured value when/where possible.

 

[Des 56]

I won't answer your question directly because I understand my favourite scam suggest what you say

I will however say that once upon a time Electricians were taught to work with electricty,now make of that statemnt what you will

One clue I will reveal,live working focuses my respect if not any avoidance fears

 

[markc123]

Absolutely not. Always test Zs on all circuits how else would you know your circuit complies with the values for maximum permitted Zs. Calculations do not allow for high impedances through some MCB's, RCD's etc.

Completley agree. I think though, that if your theoretical Zs complies it's fine...which is stupid. Theres an apprentice, that used to do abit with me - now with another sparky i know, and apparantly on the 2395 testing and inspection practical exam they wouldn't allow any live testing of the circuits...all measured, and this was fine by them.

 

[trev]

We are supposedly skilled professionals, if we can't conduct a live test safely then perhaps we're in the wrong line of work.

 

[THE INVERTER]

Re: No live testing except where it's a must

​

Trying to work out how to do a dead Ze test
lol

 

[Adam W]

Re: No live testing except where it's a must

​

Trying to work out how to do a dead Ze test
lol

Do you agree that we only should be working dead when establishing the Zs for final circuits other than socket outlet circuits? That is, don't use the line, neutral and earth probes of the E/L tester except for Ze and Ipsc. Simply add R1+R2 to Ze.

......

 

[farmerian]

I won't name the company but they one company out they that gone Heath and safety madness, your not aloud to test live without signing a folder of paper work

 

[Les Macaulay]

I agree with all of you but the local college doesn't advise live testing of Zs, just as Markc123 said above. Is there not a call for say BC adapter leads and small and large and giant ES adapter leads for loop testers? So no H & S inspector walking in on me probing behind a FCU for a Zs reading would be critical? Same at any other live terminals, except at the incoming supply with the main earthing lead disconnected and the CU main switch open?

 

[Les Macaulay]

I did qualify that, inverter!

 

[Des 56]

So no H & S inspector walking in on me probing behind a FCU for a Zs reading would be critical?


If he was to play his silly H+S games whilst I was working live and possibly distracting me in any way,he would soon have my very rigid H+S boot targeted straight up his rear end and would be more concerned with extracting the said rigid boot out of his rear end than being critical of my practices

 

[Adam W]

How is testing the incoming supply safer than testing the furthest point of a circuit? The furthest point would be protected by an MCB and RCD, the incomer just by the service fuse.
I suspect the reason for 'having to' test Ze live is because 'there's no other option', which doesn't make it any safer.

 

[trev]

I agree with all of you but the local college doesn't advise live testing of Zs

So what about Ze, PEFC,PSCC? Or are those live tests acceptable? I've probably never heard such nonsense. Rather than discouraging these tests they should be teaching students how to carry them out safely and properly.

 

[Les Macaulay]

Adam, that's all very well but I was told of a factory inspector or similar reported a spark who was working in a warehouse that had been flooded and left the app standing by at the main dist board as a "safe Isolation". Again if these guys did appear on site you cannot assume you know better even if you think you do. I feel the same as you but have to respect the bofins.

 

[moose]

Calcs are ok in some cases maybe a percentage to help speed you up in this get it done world we live in, but not for all the test sheet the calc for a ring main is not the same as Zs=Ze+(R1+R2), Can you Tell what it is yet

 

[Les Macaulay]

It's because there is no option other than live testing. A socket is ok as the test lead is designed to be safely plugged in, they say. I'm not arguing against live testing, simply stating what is recommended by trainers on the Inspection Courses.
We were made to wear gogles while doing the live Ze test and comply with the rule earth, neutral then line order of probing and the reverse when finished the test.

 

[Les Macaulay]

sockets are tested live

 

[Sintra]

I agree with all of you but the local college doesn't advise live testing of Zs, just as Markc123 said above. Is there not a call for say BC adapter leads and small and large and giant ES adapter leads for loop testers? So no H & S inspector walking in on me probing behind a FCU for a Zs reading would be critical? Same at any other live terminals, except at the incoming supply with the main earthing lead disconnected and the CU main switch open?

Well ask your college how they can determine 100% that disconnection times will be met. Say you are testing final circuits from a BMS are you saying that calculation will give you the Zs from your R1+R2 and your Zdb.

 

[trev]

The trainers are idiots. the rule of earth neutral then line and the reverse is common sense though.
Now and again you may come across a situation where you may have no other option but to work live, a lot of guys on here will have been in that situation. Apparently we're not allowed to even consider doing that now.

 

[markc123]

I agree with Trev and the gang that it's complete nonsense. However, on my travels from what i hear i do think that what Les is saying is correct (no matter if we all disagree with it) - they are discouraging live testing as much as possible now a days, thus all the apprentices are getting told and brought up as if its incredibly dangerous when they should be shown how to live test safely IMO.

 

[Adam W]

Adam, that's all very well but I was told of a factory inspector or similar reported a spark who was working in a warehouse that had been flooded and left the app standing by at the main dist board as a "safe Isolation". Again if these guys did appear on site you cannot assume you know better even if you think you do. I feel the same as you but have to respect the bofins.

In that situation I would argue that if it's so dangerous to test Zs then there's no way you should be testing Ze. If there's no better way to safely isolate and lock off, leaving a suitable sentry by the switch is acceptable IMO.
When I did my 2391 we measured Zs on all the circuits except a 3 phase socket, which would involve dismantling it to expose live parts with a 400v potential between phases. I would argue with the H&S jobsworth that while he might not be a skilled person and thereby competent to test live, I am.

 

[Les Macaulay]

Again, Markc123 is reading from the same song sheet as I. There is no doubt that live testing is the only true reading you will get but if R1 +R2 measured dead then added to Zs, is within the limits imposed for disconnection times then I think that everyone will accept the reading attained this way.
Thanks everyone