Is the UK the only country that continues to permit and deploy TN-C-S earthing systems?

Just updated the numbers

Going through this discussion one of my takeaways is that no one has quoted any serious injury or death from open pen faults in the UK. There are about 1 million home ev charge points installed in the uk. Assuming that at least 900,000 have open pen detection and open pen detection adds £100 to the price, that means the public have so far spent £90 million protecting against a problem that hasn't caused any serious injuries so far. Is this actually a proportionate reaction to the risk. The biggest benefit or downside of open pen detection is that it's showing how poorly UK supply voltage is managed at the moment, with local supply networks failing to deal with massive changes in demand or moving to surplus.

I suspect that adding an open PEN detector to a wall charger costs a lot less than that.  It will already have a microcontroller, and relays to cut the power to the car.  All they need to add is a way of measuring the L-N, L-E and/or N-E voltages, and a bit of software.

But the point is valid - even if was free and all  it did was add 15 mins of labour to the installation and commissioning time, it is a non-negligable cost .and that money will come from not doing something else instead. Which may be something trivial like a safety improvement to the hot water system or skipping a service on the car, or something really important like drinking an extra few pints on Friday that affects the nations mental health.

Mike 

I have to admit that my initial feeling was that 1M EVCPs was a lot, but there are more EVs.

In terms of risk, when did your DB last trip? Are all those fuses/MCBs/RCBOs really necessary?

What price a life? I think that we have discussed this in the past and arrived at the conclusion of £1M.

Fuses and MCBs also protect against the risk of damage to property, which helps to justify their expense. Do open-PEN devices do that?

What labour?  Having checked with the manufacturer's web site, my charger has a dedicated chip on its motherboard.  The installer doesn't have to do anything to make it work.  No earth rod is required.

Alan B said:

Going through this discussion one of my takeaways is that no one has quoted any serious injury or death from open pen faults in the UK.

As this link discusses, deaths due to low voltage electricity of any cause are relatively low in the UK: https://elecsafety.co.uk/the-risks-in-underestimating-the-danger-electricity-poses-in-the-workplace/

The way the statistics are gathered, there is no way of telling whether any of those were in any way due to PME issues of any kind.
I don't believe there is any way to access non-fatal shock statistics categorised in a way that might show shocks from PME occur ... but it's a well-known phenomenon about the "shock from the garden tap" even if there are no statistics to back it up.

Since the Government have highlighted the issue (see my earlier post in this thread) along with other industry guidance including ENA Engineering Recommendation G12/5 (and its predecessors), it's not a simple matter to "back-peddle" on this subject.

Indeed, the Health & Safety Laboratory Report of November 2012 Charging of Electric Vehicles at Domestic Dwellings Using Protective Multiple Earthing (PME) - Risk Analysis states (main findings, page 4) that, whilst the risks associated with PME supplies and EV charging is 'broadly acceptable' (at least for domestic charging) based on conservative estimates and assumptions, the findings also state: "With this level of risk additional control measures to reduce risk should be implemented if it is reasonably practicable to do so, but a less onerous justification would be required than if the risks were to fall in the higher risk ‘Tolerable’ region."

So perhaps in this case, absence of [firm statistical] evidence is definitely not evidence of absence [of risk of a potential fatality].

gkenyon said:

As this link discusses, deaths due to low voltage electricity of any cause are relatively low in the UK:

I am surprised that the mortality rate is so low.

One f the problems (if one can call it that) is that people get electrocuted one at a time, so there might just be a snippet in the local paper at most. By contrast when bridges or buildings collapse, or aircraft crash, it makes the headlines even though the risk may be significantly smaller. 

gkenyon said:

As this link discusses, deaths due to low voltage electricity of any cause are relatively low in the UK:

I am surprised that the mortality rate is so low.

One f the problems (if one can call it that) is that people get electrocuted one at a time, so there might just be a snippet in the local paper at most. By contrast when bridges or buildings collapse, or aircraft crash, it makes the headlines even though the risk may be significantly smaller. 

Chris Pearson said:

I am surprised that the mortality rate is so low.

Actually there are very few electrocutions of any kind in the UK compared to almost any other 'common' cause of possible death that is present in nearly every household. When part P was coming in, and again when it had its ten year review, I looked into this, and found that it had had no significant statistical effect, unless (as at least one body was doing) you cherry picked particularly bad years before to compare with good years after. Otherwise all you see is a falling accident rate that has stopped falling.  But the data is very noisy, as you are looking at a few tens of fatalities per year in a bad year, and single figures in a good one, and when you dig into the details of each accident, which is quite practical, given the low numbers, some are so weird they should really be discounted from the total as being a situation that will never happen again.

There are more fires, but mostly due to appliance and extension lead faults not wiring.

There are figures for lost neutral events, as per the report above but most result in tingles, cursing and maybe some damaged kit. The DNO helplines are told to prioritize calls that sound like this and they tend to get sorted quite fast.

Mike.

I would further add that (if memory serves me correctly) the risk level discussed in the HSL report was estimated at less than 1 in a million per year, with each possible risk event coinciding with someone touching a vehicle on charge, coinciding with an open-PEN event (the assumption being any open-PEN event is a possible fatal shock).

We have less than 1 million chargers in the UK at present, and we know that not every open-PEN event would lead to a fatal shock for a number of reasons ... at the same time, there is definitely anecdotal evidence of electricians and charge point / OPDD manufacturers reporting possible PEN faults - which turned out to be real PEN faults - because of OPDD operation. (Just to ensure a balanced argument, there are also issues where unwanted operation of OPDDs has led to reporting of faults that didn't exist!)

But, all this goes to show that a serious shock or fatality due to an open-PEN event is entirely possible in the UK (say every couple of years or so) with the number of charging points we have now (although still very unlikely as the HSL report says), and to my mind, if some form of protection might save a lives, should we not fit that?

Unfortunately (or fortunately) with the provisions in BS 7671, and charging points either being TT, or having OPDDs or some other form of mitigation, the only statistics we will hopefully gather are "no further evidence of shock from EV charging".

(if memory serves me correctly) the risk level discussed in the HSL report was estimated at less than 1 in a million per year

Also from memory, I think another way of seeing the same risk (given the number of consumers and one fault can affect several consumers) is something in the region of 1 open-PEN fault per day, across the UK.

   - Andy.

in the region of 1 open-PEN fault per day,

To be set against a background UK level about ten traffic fatalities and ten times that crash injuries leading to hospitalization, and of course up to 3-4 thousand natural illness type fatalities per day, rather more in winter, but less in summer, mostly in the older age groups.
Important to put various sorts of risk into perspective.
Mike

mapj1 said:

To be set against a background UK level about ten traffic fatalities and ten times that crash injuries leading to hospitalization, and of course up to 3-4 thousand natural illness type fatalities per day

Happily, you seem to be out of date, Mike. Rather fewer than 5 deaths daily.

It's not ideal. But at a high level large organ8sationscand government's have to put a number on acceptable cost for saving a life. Admittedly they are probably more willing to spend consumers money than there own.

If the national health / NICE were given say an extra 30 million a year I am sure they would save much more than 1 extra life a year. Or improve the life of many more.

I realise that it's not comparing apples with apples but at some point someone should be making value calculations on improving technology.

Alan B said:

If the national health / NICE were given say an extra 30 million a year I am sure they would save much more than 1 extra life a year. Or improve the life of many more.

Could be considered politics, but I'm sure there are stats that might show a different story (however, being politics, the answer might be "It's underfunded at present, so what do you expect?"

... perhaps not a good comparison.

I still think the most telling part of safety, is that we accept the quantity of road deaths that we do, and as a population are often critical of initiatives and innovation to improve road safety, yet there may well be a huge outcry if someone is electrocuted.

To be plain, though, neither road deaths, nor electrocutions, should be acceptable today.

gkenyon said:

I still think the most telling part of safety, is that we accept the quantity of road deaths that we do, and as a population are often critical of initiatives and innovation to improve road safety, yet there may well be a huge outcry if someone is electrocuted.

Even if motor vehicles were preceded by an escort, there would still be fatalities, but they might be rarer than electrocutions.

I do not think that RTCs are accepted as such, but they are an inevitable consequence of human failure, and in some cases recklessness. Just as we could avoid electrocution by doing away with electrical installations, we could avoid RTCs by doing away with motor vehicles, but as Graham says, it is what is politically acceptable that matters.

Chris Pearson said:

it is what is politically acceptable

or acceptable to society in general

And to that end countries where the other risks are higher, quite correctly, worry far less less about both road and electrical safety, but I don't recommend any European to cross a major road in any Indian city without asking a local where is a safe place first !
Of course if at some point our prosperity and value of life falls, then we will need to be ready to adapt downwards in a similar way to a more affordable, but higher risk lifestyle.

Some level of risk is perfectly acceptable, but the pain cost balance point depends on external factors.

Mike.