basic bad practice

[ackbarthestar]

(not 'convenient' is not a reason)

As far as business is concerned it is a very good reason why the supply cannot be disconnected.

However, when conducting a PIR/EICR, verification of the protective system to the distribution boards and final circuits is achieved by the measurement of the earthing system connected since this is what its there for. You wouldn't expect to have a real fault under test conditions would you?
There are those 'purists', when doing a PIR, who believe the only way to test final circuits is to isolate each one in turn and live test separately. That method might be Ok for a small installation where you have total and continual control of the isolation process, but this is very rarely the case and so other suitable methods have to be used to assess the worthiness of the protective systems. Zs/Zdb is one method.

 

[Stevesplatto]

Well, I think for the majority of the 22million households in the UK it's entirely practical to follow GN3 and safe working practice and isolate the supply. As stated the Zs method won't pick up all potential faults and should not be used as a first choice method, clearly..
I find it really odd how the scenario that applies to the majority of domestic situations is ignored and the exception is somehow presented as the norm to defend a company that presents Zs testing as its default method. Sniddy little comments questioning my good practice and commenting on experience and qualifications that havnt been stated kinda soured what could have been decent discussion. I wonder how many on here just take a set of Zs readings and simply make up the continuity figures... (but that's a diferent thread..)
A lesson learned...

 

[ackbarthestar]

Found this on a large testing companies website:

'Where the mains supply is connected, as will be the case for periodic testing, the protective and equipotential conductors must not be disconnected because if a fault occurs these conductors may rise to a high potential above earth. In this case, an earth-fault loop tester can be used to verify the integrity of the protective system.'

So wrong, I wonder how many wrongly measured Ze readings they've reported (parallel paths). I emailed them suggesting they might consider turning of the main isolator to reduce the risk of the conductors rising to 'a high potential above earth' before disconnecting the main earth for a real Ze test..
Big company as well..

Ride em cowboy!

and then....

Well, I think for the majority of the 22million households in the UK it's entirely practical to follow GN3 and safe working practice and isolate the supply. As stated the Zs method won't pick up all potential faults and should not be used as a first choice method, clearly..
I find it really odd how the scenario that applies to the majority of domestic situations is ignored and the exception is somehow presented as the norm to defend a company that presents Zs testing as its default method. Sniddy little comments questioning my good practice and commenting on experience and qualifications that havnt been stated kinda soured what could have been decent discussion. I wonder how many on here just take a set of Zs readings and simply make up the continuity figures... (but that's a diferent thread..)
A lesson learned...

Lol....

 

[Stevesplatto]

and then....



Lol....

gal...

 

[Brightspark2]

Well, I think for the majority of the 22million households in the UK it's entirely practical to follow GN3 and safe working practice and isolate the supply. As stated the Zs method won't pick up all potential faults and should not be used as a first choice method, clearly..
I find it really odd how the scenario that applies to the majority of domestic situations is ignored and the exception is somehow presented as the norm to defend a company that presents Zs testing as its default method. Sniddy little comments questioning my good practice and commenting on experience and qualifications that havnt been stated kinda soured what could have been decent discussion. I wonder how many on here just take a set of Zs readings and simply make up the continuity figures... (but that's a diferent thread..)
A lesson learned...

From what you have posted it doesnt say if its domestic, commercial or industrial...with the method they have described we just took the job as being in an industrial/commercial situation where the power cant be switched off for various reasons. I took it from being a large testing company that they will mostly be testing that sort of installation rather than being domestic where most people get a local spark IMO...

May be better if you posted up a link to the site...

 

[Guitarist]

Since 1986 I have worked for several very large companies, and every one of them has had an annual "shutdown", where engineering gets total control of the place for a week or two for the purpose of carrying out essential work which can't be done during production. I understand that certain institutions need to run 24/7, 365, but there are many occasions when isolation is quite possible but it is easier not to bother due to the hassle of resets etc.
I understand the economics completely, and I'm not saying that certain alternative methods (assuming you have the original system Ze readings as reference) are wrong, but it is funny how certain practices (such as storing fuel) go out of the window when it suits for political or financial reasons.

 

[ackbarthestar]

I agree, if you can get a full shut down then there are all manner of tests that can be done to verify compliance with the regs.
However, as far as I can see there are some companies that rely on preventative maintenance using fully automated management systems which would be impossible to test in 'conventional' terms.

Basic one isolator one distribution board domestic systems can be verified easily by switching off. But why would you need to if previous results were available, an inspection showed that all the main bonding conductors and other earthing arrangements were in place? You then only need to verify, Protective measures, IP ratings, Breaking capacities, Maximum demand and that disconnection will occur within the stated times and that a 'Numpty Ban' label was attached to the consumer unit