Max Zs readings where circuits are protected by 30ma RCD's

[baldsparkies]

Sorry Malcolm, but i've read that report every which way and backwards, it's full of holes and it's test data is based on far too few examples to come out with the statements it makes to have any meaningful or justifiable conclusions. On my last project alone, we had more RCD device failures than the whole of the examples mentioned in this report...

To get an idea of the true failure rate, you only have to look in this, and other on-line Forums. they are an everyday occurrence!! The truth is, that today's RCD devices are not as fail safe as the manufacturers would have you believe. That's not to say that they are not improving all the time, it's just that there not quite there just yet!!! lol!!

You don't need forums or word of mouth or statistics.
You can go by your own experiances with the blooming things, and I have seen plenty not working or lazy RCD's in my working life.

 

[Engineer54]

Of course there are failures, no product is perfect, but you can't use forum posts as an example, who joins a forum and posts about the longevity and reliability of their RCD/RCBO?

There are vastly more RCD/RCBO devices being installed now than at any other time due to the requirements of BS7671:2008 yet failure reports (even on forums) don't appear to have risen in proportion!

When was the last failed RCD/RCBO post here?

And more importantly, where is there a documented case of accident or injury attributed to a failed RCD/RCBO?

We've had this conversation before, me thinks!! lol!! Now are you saying that there aren't many RCD failures reported on this and other electrical forums?? I must reading phantom posts on these forums...lol!!

Yes your right, there is an ever increasing number of RCD devices being installed these days, along with an ever increasing failure rate to match those numbers. Don't get me wrong here, i most certainly fully support the use of these RCD devices, but that doesn't mean i would totally rely on them. Seen far too many RCDs having to be returned to the manufacturer for replacement, to have the blind faith that you seem to have in them.... I have seen a marked increase in RCD device failures over the last 10 to 15 years, mainly because of the increase in the numbers being used on my projects. These are not the budget type units either, these are all from the best names in the industry....

The old chestnut of you not knowing of any accident or injury caused by any such failures of RCD devices is neither here nor there. You could easily of said the same for lack of bathroom supplementary bonding, before the advent of any requirement of RCD devices.

 

[Des 56]

At the end of the day,electricity is a potential danger and whatever preventative action is taken,the risk remains
We can minimise the risk by following all the good working practices and using correct protective devices,but the risk never goes away

Any electro/mechanical device can fail,if the failure rate was so bad,electrical work would be taken as seriously has gas installation

It isn't,therefore the whole TT/ rcd discussion is unlikely ever to become an issue

 

[nick611]

ok i,ve read this thread and i,m confused. are you saying tt systems on an rcd are unsafe?. Because theirs no way to get a complient zs on one of these and if an rcd solves this problem then why should it be any different on a tn system.

 

[baldsparkies]

I am saying, that a car with an anti lock braking system is a nice safety extra. But you still have and need good brakes.
Where TT is concerned If an RCD is an ABS system, I don't think much of your brakes.

 

[IQ Electrical]

I am saying, that a car with an anti lock braking system is a nice safety extra. But you still have and need good brakes.
Where TT is concerned If an RCD is an ABS system, I don't think much of your brakes.

I might campaign for a recall on this car but I can't find any accident statistics, Watchdog are not taking this one!

 

[tester11]

why would u leave an installation with 68.4 ohms as a Zs, 1667 ohms or not that is clearly something u would investigate. makes u wonder wat goes thru some folks head !!!!