Discuss An interesting exchange today with Contactum, IET & NAPIT in the Certification NICEIC, NAPIT, Stroma, BECSA Forum area at ElectriciansForums.net
Yes we have oven ready Pyrex glass ... but you missed my key point, if you heat up only one spot of glass the stresses between the hot and cold areas can cause it to shatter, fracture, crack etc ... oven glassware is heated up more or less evenly so little issue but car windscreen are a good example for shattering or cracking when you poor boiling water on it to melt the ice. The link gave limited info on properties of the glass so may not be suitable or even cost effective.
Just look up exploding pyrex dishes etc ..consumers ignoring usage warning and putting a hot dish under a cold running tap is one way to achieve this.
Glass is an insulator so is prone to temp' differential stress where as metal is a good heat conductor and doesn't shatter with high temperature gradiants across its surface.
... depends how cold you make it and how hard you hit it ... though I have seen an experiment where a brass tube was put in liquid at room temperature and within a minute or so it was in 'shard' like pieces, looking like it had shattered. A combination of unrelieved stresses from manufacture and corrosive environment causing failure by stress corrosion.
surely the root of the problem is not that the consumer units are combustible or not, but why they catch fire!!!!! instead of making all domestic consumer units non-combustible so that they just contain any fire that may/may not be occurring they seem not to have addressed the cause of the problem which is likely to be poor terminations or overload situations - these are still going to be there, just hidden away.
would it not be better to try and sort out the cause through teaching people how to terminate cables and not overload circuits, more inspections on domestic properties etc etc. But no lets just ignore the causes and opt for an easy way out.
cant see that this new regulation will solve anything.
surely the root of the problem is not that the consumer units are combustible or not, but why they catch fire!!!!! instead of making all domestic consumer units non-combustible so that they just contain any fire that may/may not be occurring they seem not to have addressed the cause of the problem which is likely to be poor terminations or overload situations - these are still going to be there, just hidden away.
would it not be better to try and sort out the cause through teaching people how to terminate cables and not overload circuits, more inspections on domestic properties etc etc. But no lets just ignore the causes and opt for an easy way out.
cant see that this new regulation will solve anything.
You make valid points but the case is that the fires still happen .. if a simple change in regulation can limit the possiblity of fire spreading and save property and lives than even one live saved can justify the regulation and as steel enclosures cost little difference to make compared to their plastic counterparts then the prices will drop and we have more time to find who's to blame in the long run.
I tend to agree, but only time will tell. This argument keeps coming and going, but for now we have to work with what is given us. As I have said before, I can't see any manufacturer producing any thing else, other than a metal CU. For them it's simple, the reg suggests non ferrous metal, so why would they bother to research (spend profits) anything else and then prove (to whoever they have to) that it's non combustible. Clearly plastic CU's were cheaper to make than metal, bigger profit margins, but for now (or next Jan) it's metal, cos that's cheaper to make than glass, ceramic or kryptonite!
Main thing that bothers me about all this, is the fact that a bad installer will still do a bad job,
There'll still be CU fires and possibly electrocutions will rise, something which was not really a problem before with insulated Cu's so by trying to solve one issue another has arisen.
The only good thing that may come from the above scenario happening is that a proper licensing scheme may be eventually introduced for electricians, with stringent criteria !
Sadly a few lives need to be lost before common sense comes into play!
Main thing that bothers me about all this, is the fact that a bad installer will still do a bad job,
There'll still be CU fires and possibly electrocutions will rise, something which was not really a problem before with insulated Cu's so by trying to solve one issue another has arisen.
The only good thing that may come from the above scenario happening is that a proper licensing scheme may be eventually introduced for electricians, with stringent criteria !
Sadly a few lives need to be lost before common sense comes into play!
Just from my own experience I've seen exposed live conductors touching the sides of insulated Cu's on quite a few occasions ie tails/singles in domestic boards that have been pinched or ripped by the cover etc and just left by the installer, several of these jobs had either no earthing/ bonding connected to the board or the ZE was ridiculously high due to poor termination
So I think it's fair to comment that as MC Cu's may/will start being installed it's only a matter of time before some idiot leaves a job with the enclosure live!
Also seen a few 3 phase boards so badly done with damaged conductors almost touching the sides again with virtually nonexistent earth's and I seriously doubt I'm the only person to see such badly done installs!
So as the majority of boards in industrial and part commercial are all metal - I assume we must all be playing on borrowed time... there is little or any higher risk between metal and plastic and deffo not enough to warrant the lives saved in house fires.... I'm sure if the industrial death rate due to the boards been metal was an issue then they would have thought about the regulations in the first place as the BS7671 covers industrial too and I see no extra measures needed for metal boards except the obvious.
If you get such a suggested poor install then they are clearly not competent or to the regs ... we cannot do anything about those that do this poor work except warn people but they will always exist...
Ok I should have explained my thinking a bit better,
I'm not really referring to commercial jobs as in the vast majority of cases the skill level of the installer is of a higher level, whereas in domestic although there are many good installers/electricians who are conscientious about their work, there are a lot of bad domestic installers/electricians around also, it seems to me that the good are slowly becoming outnumbered by the bad!
My view is that as many others have previously said the majority of CU fires are caused by poor workmanship, so the reaction of changing the spec for boards is a good thing, but as it seems to be that domestic MC boards may become the norm again, rather than non combustible insulated
So the bad installs of course will continue as will fires
and for example the jobs I'm referring to the result could easily be deaths or injuries from electric shocks if they had been of metal construction .
The issue of poor workmanship and unqualified persons has again been sidestepped, this should have been addressed as it's long overdue.
This was yet again a good opportunity for the industry to become better regulated and denying those without the skills, inclination to do a decent job from staying in the trade
I was going to say that it is hard to get a DB live because they are solidly earthed and you would have to miss all forms of earthing for the PD not to operate if a live touched tha case, but then realised that you could take the earths to the neutral bar and vice versa, that would be dangerous.
Reply to An interesting exchange today with Contactum, IET & NAPIT in the Certification NICEIC, NAPIT, Stroma, BECSA Forum area at ElectriciansForums.net
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