mapj1 said:

1) That some sort of standard is being developed for PEN fault detection is an excellent step forward and to be applauded - for a while we have had the slightly unusual situation that a potentially safety critical device is called up in a standard, but there is no ' and it shall perform like this' requirement to refer to.

I agree, I think that a UK standard for PEN fault detection and a testing system (factory testing and also Electrician onsite testing.)  is well overdue.  I think that the likes of Megger, CA, TIS, Fluke need to get involved as I suspect that a real world test of a PEN fault detector in a Domestic Dwelling or a Commercial/Industrial scenario will have its own set of technical chanllenges.

For the last few years people have been fitting PEN fault devices and also EVSE which claim to have PEN fault detection built in them with no real way of knowing if they will work correctly.

As a side note.   Could a PEN fault detection not be enabled in a Smart meter in some way?

Could .... detection not be enabled in a Smart meter... ?

Oddly we did discuss this very thing a while back but that part of the forum is no more, or I would just link to it.

But the conclusion was "yes" at least for the simple mode of detection that does not need an electrode - i.e. cut off if the L-N voltage goes widely out of spec for more than the usual inrush period of large loads, it certainly would be technically feasible, and as a bonus save the most expensive damage that a lost PEN causes.

Indeed some drawings that look  very like the vector phasor-grams that appear in the draft spec were produced by one of the forum regulars to aid the discussion and to show the corner cases that the technique would not cover.

Sadly, rather like the argument that 'we would like an isolator (or even an RCD) at every meter point as part of the smart meter roll-out' that ship has sailed, and the cheapest solution with no such additions has won the day as the de-facto standard.

And despite promises to do so , even the idea of periodic visits to check the smart meter meter and main fuse for signs of impending failure seems to also be falling by the wayside.

Mike

Could a PEN fault detection not be enabled in a Smart meter in some way?

In principle, yes, we have discussed the possibility here before (and would have other advantages, e.g. informing the DNO of the problem as the same time, so reducing the risk as time to repair would be reduced, not to mention reducing the magnitude of the diverted N current by disconnecting loads). The gotcha in term of EVs though is that disconnecting the PE at the origin is often defeated by main bonding to services shared with other installations - to the EV might still be connected to the dangerous PEN - via the  c.p.c. to MET to main bonding to pipe to next door to their bonding to their MET and to the DNO's PEN. Putting the device next to the EV should eliminate parallel paths when the contacts are open.

   - Andy.

The meter can't even disconnect the PE in the consumer's own installation, as we currently wire things.  We would have to switch to the American system where the N-E link is on the consumer's side of the meter.

I must admit that when I saw the title of the thread, I thought that this was a new proposal for yet another safety device at the origin or in the DB.

Might there be some merit in this option for new builds where mains services arrive in plastic pipes and a new type of meter could be mandatory?

Or just have a triple pole switch in the meter rather than a single pole one?

   - Andy.

Chris Pearson said:

I must admit that when I saw the title of the thread, I thought that this was a new proposal for yet another safety device at the origin or in the DB.

This sort of device wouldn't be effective in installations with extraneous-conductive-parts that are shared with other installations, or other connections to the PME system ... it would only work for equipment outdoors.

A device that reports back to the DNO so they could investigate areas they are getting multiple "pings" from, would be far more effective.

gkenyon said:

A device that reports back to the DNO so they could investigate areas they are getting multiple "pings" from, would be far more effective.

Surely not difficult to put in a smart meter.

I fully appreciate the limitation concerning extraneous CPs, but do modern dwellings have them?

Or indeed if it allowed the DNO to decide to automatically switch off the local substation after some no of fault reports.

None of this is possible at the moment, politically as the functions of DNO and metering company are separated, and physically as substations currently do not have remote controlled LV switching, and the HV areas, that do, cover too large an area for practical fault isolation. But if far sighted good engineering were paramount in the design of the smart grid, it is the sort of thing that would be going in about now to keep it going for the next couple of hundred years.

Mike

None of this is possible at the moment, politically as the functions of DNO and metering company are separated,

Not entirely - SMETS 2 meters don't talk direct to your supplier (unlike the older SMETS 1 ones) - but to one centralized organization (the Data Communications Company (DCC)) - which then passes data on to the appropriate supplier (thus allowing the meter to remain 'smart' when you switch suppliers). So data could be passed onto the appropriate DNO just as easily (and apparently some DNOs are getting power loss data and have been acting on it - e.g. sending someone out in a van to berate whoever had pulled the service fuse without authorization).

   - Andy.