Metal enclosure with 3rd amendment.

[bernardgreen]

I can't see a single fault increasing the risk. It would require a Live to Case fault and a loss of earth to the case before the case became live.

Not with a TT installation where the live-case fault is upstream of the RCD.

It is a given fact that in a TT installation any fault Live to CPC between the incomer and the RCD is unlikely to operate any protective device. The CPC will be at Live potential, every appliance will work normally and inside the "Faraday cage" of a perfect equipotential zone people will be not be at risk of getting a severe electric shock.

But there will be steep voltage gradients around the ground rod and the risk of receiving mild to serious electric shocks as a result of these voltage gradients is significant.

 

[DaftPunk]

Just design the installation so a L to E fault is not possible.

I really think you're over exaggerating the potential risk.

 

[bernardgreen]

Just design the installation so a L to E fault is not possible.

It can be done, using cases made from non conducting material would make it easier to design that fault immune system.

I really think you're over exaggerating the potential risk.

I agree the risk is small but not insignificant. Voltage gradients through the ground are seldom taken into account during the design of the system. The exception is on farms where animals can be affected by them.

 

[ban-all-sheds]

A lot of the regulations and restrictions we have to live with (and some moan about, citing the 'Nanny State') these days are designed to "protect people from themselves" (or "from their own stupidity").

Which is fine.

Until those regulations and restrictions unreasonably constrain and hamper the actions of those who are not stupid, at which point "let the stupid burn" becomes my position.

In fact, I wouldn't even have been surprised if the regs (aka Mr/Ms Nanny State) had actually demanded that metal CUs be 'effectively insulated', and if scratches penetrating the coating therefore resulted in EICR 'fails'!

I know - let's make them out of asbestos!





Oh, err, hang on a mo.. maybe not...

 

[securespark]

//www.diynot.com/diy/threads/w...ged-in-the-18th-edition.424382/page-2#3296794

 

[JohnW2]

AIUI electrical safety regulations (for both installations and appliances) are based on the principal that once you use a tool to enter an enclosure you have crossed a line and safety becomes your responsibility.

In many senses that is true, although I don't think that means that the contents of the enclosure can be as dangerous as one likes, yet remain compliant with those regs, provided only that one can only open the enclosure with a 'tool'.

Whatever, those regulations exist in the real world, in which there are investigative journalists, politicians, coroners, aggrieved relatives of victims, 'pressure/consumer groups' etc., hence 'public opinion'. If, despite the above, there were suspicions that a new "electrical safety regulation" had resulted in, say, an increase domestic electrocutions, then I am sure there would be some 'fireworks' - and at least calls for the 'safety regulation' to be reviewed.

Kind Regards, John

 

[JohnW2]

A lot of the regulations and restrictions we have to live with (and some moan about, citing the 'Nanny State') these days are designed to "protect people from themselves" (or "from their own stupidity").

Which is fine. Until those regulations and restrictions unreasonably constrain and hamper the actions of those who are not stupid, at which point "let the stupid burn" becomes my position.

Whilst I have some sympathy with that position, I need not tell you that it is seemingly not acceptable in this day and age.

Kind Regards, John

 

[ban-all-sheds]

I know.

Need judges to start saying things like "You were an idiot, it was your fault, go away".

 

[DaftPunk]

Just design the installation so a L to E fault is not possible.

It can be done, using cases made from non conducting material would make it easier to design that fault immune system.

It can be done quite easily with a metal consumer unit.

I guess this whole debate comes down to people who just don't like change.

I remember exactly the same whining when RCDs became mandatory.

 

[JohnW2]

I guess this whole debate comes down to people who just don't like change.

There's bound to be an element of that - such is human nature. However, as I keep saying, I think the main current issues is that of misunderstandings. Despite what one might think from a lot of what is being said and written, no-one is being told that they will have to change using to metal CUs in domestic installs.

As I've said, it will be interesting to see how the situation evolves once the dust of the misunderstandings and knee-jerks has settled a bit!

Kind Regards, John

 

[ban-all-sheds]

http://www05.abb.com/global/scot/sc...579ca002d8907/$file/k0119_the_new_iec_web.pdf

 

[stillp]

A more independent guide:
http://www.gambica.org.uk/web_images/documents/publications/GAMBICA_BS_EN_61439_guide_Ed2_2013.pdf

 

[ban-all-sheds]

But not a guide to 60439-3, sadly.

 

[stillp]

True, but neither is the ABB guide.

 

[stillp]

This might be interesting:
deleted /technical_bulletin_-_enhanced_fire_safety_from_consumer_units.pdf