testing zs - EAWR

[hillbillie]

I phoned the DNO once regarding a Ze reading; the scenario in my previous post was what I was told. I told the woman the address and the earthing system (TN-C-S) and received the quote of 0.2 ohms. I then said "no, sorry, its TN-S" and she revised the figure to 0.8 ohms!

It appears that the DNO round my way has done lots of tests and all TN-S installations are 0.8 ohms and all TN-C-S are 0.2 ohms.

My tester read 0.2 ohms, I seem to remember, for this TN-S installation, but what do I know!

 

[PEG]

Although its possible to calculate many of the values we use and require,in a lot of instances,this is better done to back up the actual measured results.Given the importance of these,it is always beneficial to have actual values to assist the accuracy of further investigation of problems which avoids calculating using calculated figures.Safety issues whilst doing this IS PART OF THE JOB. Isnt that pause, whilst your MFT makes its mind up, why we do this job? Anyway,didnt they "calculate" that 45 minutes thing which lead to Iraq?.....should have dropped that bonding and put their probes on Bagdad.............

 

[jimmy_one_ball]

As far as I'm concerned mate, it couldn't be simpler. I do a live Zs on socket and cooker circuits simply because I can plug the test lead directly into the socket outlets without opening the enclosure. Lights and water heaters etc I do dead and by calculation simply because it is illegal to work on or near live conductors (EWR1989 regulation 14). I know on the NICEIC schedules it asks for a measured value but I would argue this point with anyone from the NIC. The law is the law and it is simply wrong to encourage anyone to break the law. Its black and white for me, they get calculated values and thats that!

 

[jimmy_one_ball]

That may also suggest the ZS has been calculated from Zs = Ze + (R1 + R2) which is what I do on any circuit that I can't plug in to

I've seen aa couple of EICR's recently where the Ze + (R1+R2) is exactly the same as the Zs which suggests that the R1+R2 hasn't been dead tested at all.

 

[ipf]

As far as I'm concerned mate, it couldn't be simpler. I do a live Zs on socket and cooker circuits simply because I can plug the test lead directly into the socket outlets without opening the enclosure. Lights and water heaters etc I do dead and by calculation simply because it is illegal to work on or near live conductors (EWR1989 regulation 14). I know on the NICEIC schedules it asks for a measured value but I would argue this point with anyone from the NIC. The law is the law and it is simply wrong to encourage anyone to break the law. Its black and white for me, they get calculated values and thats that!

With a make believe Ze value via telephone ?

 

[telectrix]

As far as I'm concerned mate, it couldn't be simpler. I do a live Zs on socket and cooker circuits simply because I can plug the test lead directly into the socket outlets without opening the enclosure. Lights and water heaters etc I do dead and by calculation simply because it is illegal to work on or near live conductors (EWR1989 regulation 14). I know on the NICEIC schedules it asks for a measured value but I would argue this point with anyone from the NIC. The law is the law and it is simply wrong to encourage anyone to break the law. Its black and white for me, they get calculated values and thats that!

so, by that reckoning, a scuba diver shouldn't work in water, he might drown, a pilot should fly his plane just on the runway in case it falls from the sky, a miner should only pick up coal if it's lying on top of the ground in case he gets buried, a gas fitter should calculate his pressure and leaks with the gas supply turned off, in case he gasses himself. .

lts take it further. why bother to use MFTs to measure R1+R2? might set it to 1000V IR by mistake and get zapped. let's measure the cable length with a tape measure, then use tables to calculate the resistance. OH NO, H&S have banned tape measures, sharp edges can cut your head off.

 

[44ALLAN]

I really can't see a problem with live testing.
My tester has insulated probes and croc clips and they fit nicely into the terminals of contactors/wall isolators/d.boards and the like.
I take live Zs readings as remote on all circuits as is humanly possible.......normally at the incoming terminals of the machine isolator ( no different to testing in domestic scenarios only these are 3 phase).
If my probes will fit then it gets tested live..........parallel paths the lot

 

[Jimmy Boy]

All this 'illegal' crap is a literal interpretation on 'Live Working' it's Live testing not live working, to the OP Jimmy one ball, how the hell do you function as a spark ? Do you never take a cover off a CU ? even with the MS off your working ' Illegally' according to your logic, unless every job your on has a DP isolator at the CU.. well you can't be pulling the DNO fuse because that's live working ? to me 'Live working' is the removal, installation or manipulation of Live conductors whilst the installation is energised, I am doing nine of these.I'M TESTING FOR GODS SAKE do you never do a Live Ze ? a Live PEFC/PSSC ? your a professional, trained competent, you have all the BS compliant testing equipment..the risk is so infinitesimally small why even drive to work you may get killed getting there..aaaggghhh