Who does just a Zs when carrying out a periodic on a lighting circuit

[nickblake]

Just answered a question on another post ,and it dawned on me , yippee the brain kicked into gear , i have read on loads of posts that people say doing an inspection just calculate the R1R2 by doing a Zs and taking away the Ze , i have never liked this method and heres a reason why , supplimentary bonding !!!!! you go into a house you do an R1R2 test you get a reading if there are any open circuits it shows up and it can be rectified , so what happens if the install is up to 16th edition all supplimentary bonding is in place ,3/4 the way through the lighting circuit there is a bathroom with an electric shower , you find the last on the run bedroom next to the bathroom quick Zs all ok , heres the scinario , the cpc's have have been cut off at the first light switch , metal clad switches and light fittings , so you test the last on the run get a good Zs reading fill in the sheet calculate the R1R2 and walk away ,so what if the supplimentary bonding has been installed between the shower and the light as it was in the 16th edition ,you then will have a reading which is false and potentially leave the entire un earthed circuit thinking its ok , so the moral of the thread is R1R2 Insulation and Zs simples easy to see the supplimentary bonding and and not put 2 and 2 together , thank you malcom for kicking my brain into gear on this one just a comment he made made me think :devilish:

 

[Sparky Ninja]

R1&R2 should never be calculated from Zs and Ze. It can only be calculated from resistivity, factors and length.
I believe that it's never been written down as an acceptable method, if it has I would like to see it.

 

[DurhamSparky]

got my arse kicked by Elecsa when i calculated on my first assessment ZS-ZE... never did it since and luckily i never got reassessed as it went down as observation only!

 

[nickblake]

Totally agree widdler but you see posts on here saying just do a Zs when inspecting , and my post is just there to high light why it should never be done , yes to calculate the Zs but not to back calculate ,

 

[IQ Electrical]

Totally agree widdler but you see posts on here saying just do a Zs when inspecting , and my post is just there to high light why it should never be done , yes to calculate the Zs but not to back calculate ,

Ha, let them try it in a decent sized industrial installation, you can almost end up with a negative R1+R2 once the parallels have taken effect!

 

[Spudnik]

On a new or altered installation there is no excuse not to carry out the dead test as well as live tests.

On a PIR..... well......errrrr....

 

[Sparky Ninja]

Totally agree widdler but you see posts on here saying just do a Zs when inspecting , and my post is just there to high light why it should never be done , yes to calculate the Zs but not to back calculate ,

If you see any of them pop up again mate can you refer them to this thread, that is advise we have to eliminate from here.

 

[nickblake]

yep i see what you are saying jason , one i will remeber did a R1R2 on a lighting circuit tested out ok , but the was something not quite right , found out that half way though the circuit the polarity changed then changed back again , 4 lights had an incorrect polarity so now i do tend to do an R1R2 at every lighting point

 

[Deleted member 26818]

I don't generaly measure or record R1+R2 on PIRs, unless the power is off.
I just conduct a Zs test at each fitting to prove continuity, and operate the associated switch to prove polarity.

 

[nickblake]

If you see any of them pop up again mate can you refer them to this thread, that is advise we have to eliminate from here.

yes mate i most certainly will

 

[IQ Electrical]

I don't generaly measure or record R1+R2 on PIRs, unless the power is off.
I just conduct a Zs test at each fitting to prove continuity, and operate the associated switch to prove polarity.

The test is 'continuity of protective conductors' and there is no requirement to have a value, only to prove continuity.

If your 'buzzer set' meets the requirements for continuity testing (current and voltage) then you're there.

Using EFLI only as a continuity of protective conductors test will probably open up a few more pages of debate....

 

[Sparky Ninja]

I don't generaly measure or record R1+R2 on PIRs, unless the power is off.
I just conduct a Zs test at each fitting to prove continuity, and operate the associated switch to prove polarity.

The key thing there being that you don't record calculated values.
I take it you don't do verification of voltage drop then?

 

[Deleted member 9648]

Totally agree widdler but you see posts on here saying just do a Zs when inspecting , and my post is just there to high light why it should never be done , yes to calculate the Zs but not to back calculate ,

There are two instances on a PIR where it IS acceptable to omit R1+R2 and just carry out a Zs.

1. Where a previous full schedule of test results is available to the inspector it is permitted to carry out a Zs test and compare to previous recorded results. If the measured Zs is the same or very close to the previous recorded Zs it is reasonable to assume the R1+R2 will also be the same and omit that test, if the results were not substantially the same the R1+R2 would need to be verified.

2. Where it is agreed with the client that an R1+R2 test should not be carried out in order to minimise disruption to essential supplies.

In both instances it should be stated on the extent and limitations section that R1+R2 tests were not carried out and the reasons why.

It is quite wrong to state that an R1+R2 test should always be carried out on a PIR

 

[nickblake]

i have to on a PIR software goes nuts if i dont fill it in , i do like to see what the readings are on an R1R2 test then i can get an approximate idea of what the Zs reading should be and take into account of parralell earth paths etc , if i dont do it the testing just doesnt feel right i know it sounds daft when you use a method for so many years , like changing from a manual gear box to an automatic i suppose

 

[Deleted member 9648]

i have to on a PIR software goes nuts if i dont fill it in , i do like to see what the readings are on an R1R2 test then i can get an approximate idea of what the Zs reading should be and take into account of parralell earth paths etc , if i dont do it the testing just doesnt feel right i know it sounds daft when you use a method for so many years , like changing from a manual gear box to an automatic i suppose

I know what you are saying,but there are plenty of situations when doing a PIR when it just isnt practical,or entirely neccessary. Technically the DB should be isolated when R1+R2 testing...which can take a considerable time on a large DB with multiple circuits.....it just may not be feasible in a typical working environment.

 

[Deleted member 26818]

Whilst I don't agree with everything within GN3, and I accept that it is just guidance based on someones opinion.
As far as I'm aware GN3 suggests using an EFLI test as being the most practical method of proving continuity.

 

[IQ Electrical]

Whilst I don't agree with everything within GN3, and I accept that it is just guidance based on someones opinion.
As far as I'm aware GN3 suggests using an EFLI test as being the most practical method of proving continuity.

It does indeed.

 

[nickblake]

LOL sorry guys who was it on here who told me off for doing live tests and that an nic bod said you were not allowed to to live tests any more due to health and safety , now that one will throw a spanner in the works lol

 

[Deleted member 9648]

LOL sorry guys who was it on here who told me off for doing live tests and that an nic bod said you were not allowed to to live tests any more due to health and safety , now that one will throw a spanner in the works lol

Yep....I've had that one thrown my way by the NIC......ignored it! :cheesy:

 

[Deleted member 26818]

LOL sorry guys who was it on here who told me off for doing live tests and that an nic bod said you were not allowed to to live tests any more due to health and safety , now that one will throw a spanner in the works lol

No idea?

 

[nickblake]

Im all for health and safety but come on where has the common sence gone ,lets all run out and do a dead Ze test , oh yes by enquiry , how are they going to know what it is, bad enough trying to get them to reseal a meter !!!

 

[Voltimax]

I've just been testing a hotel. Not possible to shut whole DB's down so I use the R2 wander lead method to make sure lights, accessories etc have an earth connection. It hasn't been possible to connect the wander lead directly to the earth point at all the DB's due to being a tripping hazard and too many doors to take it through. so I connect to earth on the nearest socket using a breakout box. Obviously I ensure there is an earth at this point, then I go round with the wander lead and make sure I get a reading, then carry out my Zs testing later. I wasn't happy doing it this way since the last 3 PIR's carried out at this hotel had R1+R2 readings recorded in the schedules of test results, however, doing it this way I found over 10 metal light fittings that had no earth connection. Obviously I felt much better about my chosen option and I had agreed it with the client beforehand and duly noted it down in the limitations box. Obviously the previous jokers just took one R1+R2 and Zs reading per circuit.

 

[IQ Electrical]

Im all for health and safety but come on where has the common sence gone ,lets all run out and do a dead Ze test , oh yes by enquiry , how are they going to know what it is, bad enough trying to get them to reseal a meter !!!

I've done live testing (including Zs) on every NICEIC and ECA technical assessment that I've ever done (a few) all without any comment from the assessor.

The NICEIC official line stems from the EAWR 1989 and the lack of distinguishing between 'working live' and testing.

 

[SirKit Breaker]

It is acceptable to just put a tick in the box for R1+R2 or R2 on a PIR, but not on an EIC. But if you are measuring or confirming then you may as well put down the recorded result anyway, this will give you something to work with next time around.

Cheers.........Howard

 

[IQ Electrical]

It is acceptable to just put a tick in the box for R1+R2 or R2 on a PIR, but not on an EIC. But if you are measuring or confirming then you may as well put down the recorded result anyway, this will give you something to work with next time around.

Cheers.........Howard

I agree that you would record the value if measuring but there is actually no requirement in 612.2.1 to record any value of resistance during a continuity test on initial verification.

If you have a continuity 'buzzer' operating at a voltage of between 4 and 24 V dc or ac with a short circuit current of not less than 200mA then you've complied with every part of 612.2.1 for the continuity of protective conductors test.

 

[MarkieSparkie]

I've done live testing (including Zs) on every NICEIC and ECA technical assessment that I've ever done (a few) all without any comment from the assessor.

The NICEIC official line stems from the EAWR 1989 and the lack of distinguishing between 'working live' and testing.

IQ, Live testing is considered working live by the HSE in HSR25.
EAWR 1989, Regulation 14, is absolute (no deviation allowed, and work is defined as any work activity not just electrical), therefore ALL three of the following conditions, in ALL circumstances must be met before a person may work live.
"Regulation 14, Work on or near live conductors.
No person shall be engaged in any work activity on or near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless:
a) it is unreasonable in ALL the circumstances for it to be made dead; and
b) it is reasonable in ALL the circumstances for him to be at work on or near it while it is live; and
c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.

HSR25 Memorandum of guidance on the EARW 1989, Regulation 14 guidance paragraph 208, states "Live work includes live testing ... ".

 

[Deleted member 9648]

IQ, Live testing is considered working live by the HSE in HSR25.
EAWR 1989, Regulation 14, is absolute (no deviation allowed, and work is defined as any work activity not just electrical), therefore ALL three of the following conditions, in ALL circumstances must be met before a person may work live.
"Regulation 14, Work on or near live conductors.
No person shall be engaged in any work activity on or near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless:
a) it is unreasonable in ALL the circumstances for it to be made dead; and.....It could be argued that a Zs test is required and cant be completed dead
b) it is reasonable in ALL the circumstances for him to be at work on or near it while it is live; and..It is if he is competant to be in the proximity.
c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury....Using an approved ELI tester in the correct manner is surely taking suitable precautions using approved safety equipment

HSR25 Memorandum of guidance on the EARW 1989, Regulation 14 guidance paragraph 208, states "Live work includes live testing ... ".

That would be my interpretation of the above guidance.....other interpretations might be devised. The problem is,with the present litigation culture,as soon as something goes wrong the sort of ambiguous guidance above will always be interpreted as live testing should not have been carried out, in order to dump on the individual concerned from a great height.

 

[TPES]

There's alot of sparks that test properly doing ALL tests correctly getting all value readings, yet there so many out there that I'm up against that do PIR's for £99, some of my competition must be bull s*****s, your day is easily took up doing PIRs correctly, or there just prepared to work for nothing.

 

[Geoffsd]

"Regulation 14, Work on or near live conductors.
No person shall be engaged in any work activity on or near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless:

a) it is unreasonable in ALL the circumstances for it to be made dead; and

HSR25 Memorandum of guidance on the EARW 1989, Regulation 14 guidance paragraph 208, states "Live work includes live testing ... ".

Does that mean we HAVE to pull cut-out when working in CU - let alone replacing it.

Oh! Wash my mouth out with WD40.

 

[Deleted member 26818]

Does that mean we HAVE to pull cut-out when working in CU - let alone replacing it.

Oh! Wash my mouth out with WD40.

Now that is a question, and the answer is probably why no one ever gets in trouble for doing such.
From a legal standpoint, can it be illegal to carry out an action that safeguards a person's safety?

 

[ezzzekiel]

short answer yes but only if it suited the powers to be where blame needed to be laid, otherwise no one gives a stuff.

 

[nickblake]

We are trained electricians electricity is our life , i just want to grab hold of the spec wearing pen pushing person that says you cant do this live oh for gods sake , like a driving schoolyour driving lesson you cant start the car up or move it just in case you crash , there are more people injured in cars so when are they going to ban them , you always treat circuits as if they were live even when you know they are dead then there is not a problem , yes maybee for a trainee who's never carried out electrical work then fair enough thats why there is training , how many places have banned step ladders , they are very safe if used correctly if not you fall off , and working plat forms arnt the be all and end all i had 6 cable clips to put in i worked off a platform fell and ended up in casualty ,slipped off a step silly thing to do if i was using stemps it wouldnt have happend sorry for going off on one just get so dam frustrated !!!!

 

[Deleted member 26818]

I must admit, it often makes me chuckle when sitting in on site inductions we are told to treat all cables as live, and not to touch them or we'll be chucked off site.

 

[telectrix]

We are trained electricians electricity is our life , i just want to grab hold of the spec wearing pen pushing person that says you cant do this live oh for gods sake , like a driving schoolyour driving lesson you cant start the car up or move it just in case you crash , there are more people injured in cars so when are they going to ban them , you always treat circuits as if they were live even when you know they are dead then there is not a problem , yes maybee for a trainee who's never carried out electrical work then fair enough thats why there is training , how many places have banned step ladders , they are very safe if used correctly if not you fall off , and working plat forms arnt the be all and end all i had 6 cable clips to put in i worked off a platform fell and ended up in casualty ,slipped off a step silly thing to do if i was using stemps it wouldnt have happend sorry for going off on one just get so dam frustrated !!!!

agree 100%, nick. whilst safe working practice is essential, if the red tape and nonsense were to be cut and more common sense applied, the only down side would be more "suits" on the dole.

 

[nickblake]

I must admit, it often makes me chuckle when sitting in on site inductions we are told to treat all cables as live, and not to touch them or we'll be chucked off site.

Sat through a site induction even though i had my CSCS card wouldnt let me on site otherwise ,went through the whole safety manual well it felt like it 11/2 hours of it , all i had to do was reset an MCB , funniest thing was it was in the office the site induction took place !!!

Tel now that would be a shame lol but what i will say i think it may well back fire because youngsters will not see the dangers , and will probably end up getting injured by the thing they are least lickly to get injured by , dont get me wrong im all for Health and safety it saves lives but feel its over the top

 

[Hawca]

In short, to the first part, you can calculate Zs, how ever never can you calculate Ze or R1+R2.

reasoning behind this is Zs only tells us an earth fault path nothing more.

Ze tells us we have an acceptable earth (not a path through the bonding etc)
R1and R2 tells us we have a physical return path via CPC (Not through parallel paths etc)

Never calculate R1+R2 or Ze

the whole working live thing..

it is unreasonable in ALL the circumstances for it to be made dead; this bit here tells us we can work live when testing... as pointed out we have to carry out Ze and Zs testing along with RCD and Ipf. we cannot and never will be able to test the when dead, and therefore have to test live.

 

[Deleted member 26818]

We don't have to test Ze or PFC as they can be determined by enquiry.
Zs can be calculated using the measured R1 + R2 value added to the enquired Ze value.
That just leaves the RCD test.

 

[IQ Electrical]

We don't have to test Ze or PFC as they can be determined by enquiry.
Zs can be calculated using the measured R1 + R2 value added to the enquired Ze value.
That just leaves the RCD test.

Yes, Spin's absolutely correct, the above are all accepted ways of deriving the figures to fill in the form, but not one of MY forms, my values are measured and confirmation of an adequate means of earthing etc. is obtained.

I guarantee that I can take a better guess at Ze and then PFC figures than any chap at the DNO can give me!

 

[malcolmsanford]

Agree with both the Spin and the IQ, though mostly an enquired Ze would only really be seeked at a designed stage, though in some cases I have known Ze obtained by enquiry on a large industrial complex where gaining access to take a measurement was virtually impossible during a PIR as it would mean closing down the entire complex. Not ideal but it is there for such occasions

 

[Sparky Ninja]

I guarantee that I can take a better guess at Ze and then PFC figures than any chap at the DNO can give me!

That's because you can bother turning up.

 

[Hawca]

We don't have to test Ze or PFC as they can be determined by enquiry.
Zs can be calculated using the measured R1 + R2 value added to the enquired Ze value.
That just leaves the RCD test.

this is fine in theory, and thats where it should stay, in design or at college.

Ze by enquiry does not nor will it ever prove beyond any doubt that an installation has a physical earth coming into the installation. the point of the PIR is to see if an installation is safe or fit for use. how can we make a judgement on this if we do not know if an earth comes into the installation?

therefore we have to test Ze, and in order to do so we have to work live.

 

[beaver74]

I have come across a water heater that had a vary healthy Zs which was taken from the water pipe .now if the pipe had been plastic there goes your earth.it is for this reason R1+R2 should be taken to prove an electrical earth