EV Charging post AMD2

[LastManOnline]

Are there any statistics with regard to the occurance of open PEN faults

Not always readily available in my experience and I have a keen interest in open PEN faults.Here is a statistic I got last night in a newsletter from my regulatory body which may be of interest.Electrical fatalies have steadily decreased since 2000.There have been no fatalities in last 3 years. This same period corresponds with the implementation of TNC-S nationwide.
Open PEN faults did,nt exist in the early 1990,s because we were TT.Now we are no longer allowed to use TT.Surprised by these statistics? I was. It does undermine my "crusade" against TNC-S but I,m happy to be proved wrong if the stats show that I,m wrong

As a aside it begs the question why we don't have devices to check for the loss of the suppliers earth on TN-S supplies which I have found more often than an open PEN

A valid point.But as pc1966 says ,it's a less serious situation than an open PEN and in reality the loss of the suppliers earth or indeed the loss of a circuit CPC will usually manifest itself either in a telltale "tittle" at bonded or exposed metalwork as soon as an appliance with intentional leakage built in is plugged in to a socket

 

[pc1966]

But that figure was never explained when Julie heard it and looking around the web it is difficult to substantiate any meaningful numbers for the occurrance of an open PEN

I think the DNO are required to report all occurrences of this, but i don't know where that would be accessible (if public at all).

The IET has a short article on the problems but no stats:

Broken PEN

Don’t panic, this article is not about broken ballpoint pens, it is concerning broken PEN conductors in PME earthing arrangements.

bit.ly

But with any extraneous metalwork bonded to a MET that isn't earthed it could cause some problems in an installation
And then we go looking for another statistic on how many installations have yet to have RCD's / RCBO's installed

That is very true, and that boy who was killed in the pub garden a few years ago was down to that sort of situation (compounded by criminal negligence getting there), but really i think the concern for EV chargers is folks are likely to be washing the cars while plugged in, so more like a swimming pool for shock risk than typical external lights, etc.

So I'm not saying an open supply earth is EVER OK and that is one critical thing to check before any work, etc, but the TN-C-S cases has more opportunities for it to cause death, injury, or equipment damage.

 

[pc1966]

Not always readily available in my experience and I have a keen interest in open PEN faults.Here is a statistic I got last night in a newsletter from my regulatory body which may be of interest.Electrical fatalies have steadily decreased since 2000.There have been no fatalities in last 3 years. This same period corresponds with the implementation of TNC-S nationwide.

From various discussions it seems it was the cables with aluminium outer PEN that are the biggest cause of the faults due to corrosion from water ingress. So modern setups with copper waveform outers, etc, in ROI may well be far less prone to it that some of the 70s era stuff in the UK.

 

[UNG]

Not always readily available in my experience and I have a keen interest in open PEN faults.Here is a statistic I got last night in a newsletter from my regulatory body which may be of interest.Electrical fatalies have steadily decreased since 2000.There have been no fatalities in last 3 years. This same period corresponds with the implementation of TNC-S nationwide.

But there has also been a greater emphasis on the fitting of RCD's in the last decade or so that would help distort the figures as well

 

[marcuswareham]

But there has also been a greater emphasis on the fitting of RCD's in the last decade or so that would help distort the figures as well

Why would that distort the figures as an open PEN is dangerous with or without an RCD, the RCD will do nothing if you have an open or high impedance PEN conductor fault

 

[marcuswareham]

I

"crusade" against TNC-S

I too am on a crusade against TNCS but it would be very interesting to know the exact figures and if there has been very little problem interesting to know why that is. To me its a rubbish system only implemented to save money, and with when with some resistors wired in a star configuration between the phases and a voltage monitoring device between the star point of the resistors and the PEN conductor you can detect a PEN fault so why is the not mandatory for the DNOs to implement this when without it the worst consequence is death without a fault condition in the consumer's electrical installation !! ? !

 

[marcuswareham]

EV chargers is folks are likely to be washing the cars while plugged in

On a video from David Savery when he installed an EV charger, he went on a little rant about why PEN faults are not an issue for EVs, due to the charger points CPC not being bonded to the cars body/chassis but instead the DC battey ground is bonded the car body/chassis and there is isolation (via transformer) between the AC/TNCS CPC/Earth and the DC ground, I have no idea how true this is , but would be very interesting if it is true, even if only for some cars

 

[Lister1987]

Broken PEN is reportable under ESQCR to the HSE so they're bound to have stats and figures, an FOI request should get them, what with them being a government body and all

 

[LastManOnline]

But there has also been a greater emphasis on the fitting of RCD's in the last decade or so that would help distort the figures as well

Rcd,s certainly a factor (though obilatory since early 1990,s on sockets) but there is no question that this same period of time has seen an overall improvement in how the trade is regulated.Obigatory registration for sparks ,regular inspections .And the fact that jail sentences are been imposed for unregulated carrying out of electrical work.

 

[pc1966]

I have no idea how true this is , but would be very interesting if it is true, even if only for some cars

Certainly the live (L & N) will be isolated from the car's DC system but I would be surprised if the charger system really met class II "double insulation" standards at that sort of power level so no CPC needed, even the filter capacitors for EMC control are likely to leak a few mA to make it fail such a classification.

But I guess the bigger problem is the "only for some cars" possibility. Unless the EV charger only mates with a specific standard that mandates CPC isolation on all matching cars then you need your class I earthing arrangement and we are back to the open PEN risk once more.

Now if we are seeing around 1 open PEN fault per day in the UK then by time we are looking at millions of EV being charged in the street we could be looking at a few serious incidents per year. That might well be far less death/injury from the driving of the EV of course, but it would still be considered an unacceptable risk by the public at large considering how well most other risks are managed and would no doubt be seized upon by the newspapers, etc.

 

[LastManOnline]

On a video from David Savery when he installed an EV charger, he went on a little rant about why PEN faults are not an issue for EVs, due to the charger points CPC not being bonded to the cars body/chassis but instead the DC battey ground is bonded the car body/chassis and there is isolation (via transformer) between the AC/TNCS CPC/Earth and the DC ground, I have no idea how true this is , but would be very interesting if it is true, even if only for some cars

Interestingly,the INDRA EV charger has an option the installer can choose where the circuit CPC is broken under open PEN faults ,thus ensuring the car metalwork is voltage free.Breaking the CPC? Thats more than a lttle revolutionary ,but if it can be done safely , I,m for it as I find it preferable to some of the current "safety measures" in use for EV chargers

 

[pc1966]

Breaking the CPC? Thats more than a lttle revolutionary ,but if it can be done safely , I,m for it as I find it preferable to some of the current "safety measures" in use for EV chargers

That is basically how the Matt:e and similar work, the major difference I guess is how they detect the open PEN condition.

Going TT is doing that from the outset by providing an alternative means of earthing (the rod).