How to activate isolation on this smart meter.

[Harry Bloomfield]

I don't think you can get an isolator between the board fuse & smartmeter otherwise the latter might loose it's marbles!

You can between meter and consumer unit.

 

[JohnW2]

Quite simply, I suggest you read regulation 537.2. ...... Semiconductor devices can not be used as isolating devices. .... For me the Internet has many billion semiconductor devices in it.

To be fair, I think that regulation is saying that the device which does the disconnecting has to be 'mechanical' (i.e. which contacts which physically separate), rather than a semiconductor (e.g. TRIAC). However, Table 537.4 does say that contactors to BS EN 60947-4-1 are suitable for isolation, and I imagine that there could well be, at least in some situations, semiconductors involved in the circuitry 'driving' such a contactor.

.... Not to mention, as you highlight, being prepared to risk your life in the hands of a hung-over electricity supply person working from home to get it right. .... Isolate the circuit. Lock it off and put the key in your pocket.

Very much so!

Kind Regards, John

 

[LeeJC]

Hi John,
No it was never my intention to use it as a safe means of isolation.
I’d pull the cut out fuse before relying on it. What interested me was I suppose the implementation by the suppliers who must be using this software driven device as a ‘safety’ device to isolate systems prior to work and for seemingly up to 72 hours.
I wrongly assumed that as an isolation device was fitted then it would be sensible to have some means of confirming and locking its state before any work was carried out on the user installation.
Seems this isn’t deemed necessary which only increases my confidence in the capitalist nature of the electrical profession. When considered in the round with other changes and the drive for AFDD’s and the whole a spark is ok but an arc is bad, oh and they’re totally not the same at all (when balancing a PD they absolutely are) you have to question is it about safety or is it about £££

 

[JohnW2]

Hi John, No it was never my intention to use it as a safe means of isolation.

Fair enough - I obviously misunderstood / misinterpreted your question.

.... What interested me was I suppose the implementation by the suppliers who must be using this software driven device as a ‘safety’ device to isolate systems prior to work and for seemingly up to 72 hours.

Prior to who doing what 'work'? Suppliers do not do work downstream of the meter, and fuses are always pulled to replace meters etc.

I wrongly assumed that as an isolation device was fitted then it would be sensible to have some means of confirming and locking its state before any work was carried out on the user installation.

Again, you seem to be assuming that the meter contains a 'means of safe isolation' (which it probably doesn't) and the the suppliers (hence meter specs/manufacturers) has some interest in what people did downstream of the meter,which they probably don't.

what was

Seems this isn’t deemed necessary which only increases my confidence in the capitalist nature of the electrical profession.

I'm not sure that I necessarily follow - although, if this is what you are implying, I do suspect that a lot of the 'increasing requirements' of regulations are, at least to some extent, due to 'lobbying' by those who have a vested interest in the manufacture and installation of new-fangled devices - and I would personally certainly put SPDs and AFDDs (in domestic installations) into that category.

However, such a cynical view may not be all that justified. A lot of it is probably due a 'well-intentioned' (but not necessarily very carefully considered) belief that whenever some new technology become available, it must be deployed - even if it is very largely a 'solution' to an almost non-existing problem!

Kind Regards, John

 

[LeeJC]

Prior to a consumer unit replacement for example. As there is no intermediate isolator between the meter and the CU where is the safe isolation point to allow disconnection/connection of the tails? Only answer is removal of the Cut Out fuse, which can be done with DNO approval but which as previously suggested likely results in an enquiry from the supplier.

No I don't assume the meter has a means of 'safe' isolation. I suggest that the meter has a means of isolation which when contacting the supplier for a disconnection is utilised and deemed by them to be 'safe'. The Aclara SGM 1400-B SMETS2 Meter certainly has a built in contactor that allows the supplier to disconnect the supply to the premises. As this is their only means of control. The cut out fuse being the responsibility of the DNO, then when the supplier provides a 72 hour window of opportunity for an electrician to disconnect/connect a CU, this is the only means they have without approaching the DNO, which the electrician could do anyway.

OVO provides a picture of responsibilities

Interesting use of the phrase 'if necessary'

This is the installation OVO manage

The only means of safely isolating the supply being the removal of the cut out fuse.

How is the inclusion of an isolation switch in this case considered 'if necessary'???

 

[LeeJC]

Extract from the documentation for this Smart Meter.

'The SGM1400-B has been designed to offer flexibility and the choice of home
area network (HAN) and wide area network (WAN) communications. As
standard, the SGM1400-B supports different AMI technologies, including the UK
CSP communications hub solution. The communications hub mechanically
connects directly to the electricity meter. The hub communicates with the meter
using the ZigBee communication protocol. A manufacturing option that provides
direct communications via a hardwired interface is also available.
The on-board ZigBee RF interface uses industry standard Smart Energy Profile
for HAN communications to the UK communications hub and in-home display
(IHD) respectively.
The standard meter is supplied with an integrated 100A switch for
connect/disconnect of the consumer supply. Certain models of the SGM1400-B
Series meter offer an optional 2 A load control relay, whilst others support an
additional 100 A contactor for control of other ancillary devices such as night
storage heating, pumps, etc.'

A 100A switch which is software controllable.

 

[Harry Bloomfield]

How is the inclusion of an isolation switch in this case considered 'if necessary'???

It means it may be necessary for the supplier to install it. It maybe be possible for an electrician to install it and have the supplier connect it later, or at the same time. In practice, many electricians will pull the cut-out fuse, install the isolator, and reinsert the fuse - then advise the supplier to reseal the cut-out.

Such an isolator is not considered to be either essential or necessary, unless the meter to consumer unit tails are longer than 1m (I think). They are always a useful option to have.

 

[EFLImpudence]

The standard meter is supplied with an integrated 100A switch for
connect/disconnect of the consumer supply. Certain models of the SGM1400-B
Series meter offer an optional 2 A load control relay, whilst others support an
additional 100 A contactor for control of other ancillary devices such as night
storage heating, pumps, etc.'

You will note that it states "connect/disconnect"; NOT "isolation".

 

[Harry Bloomfield]

A 100A switch which is software controllable.

Controllable remotely, by the supplier.

 

[LeeJC]

Yep I did spot the semantics around 'connect/disconnect' and the exclusion of isolate. Then again when I disconnect the cut out fuse, isn't the system isolated?...................................
Harry, yep controllable remotely by the supplier and one of the two means of disconnecting or isolating the incoming supply. The other being the cut out fuse with the big 'YOU'LL BURN IN HELL' sticker on it.
The if necessary thing baffles me. As the only means to mechanically disconnect/isolate the incoming supply is the cut out fuse, how has this forward movement in technology resulted in a safer installation. It hasn't, we are still left pulling out the 'it'll likely explode in your face' cut out fuse.

 

[EFLImpudence]

Yep I did spot the semantics around 'connect/disconnect' and the exclusion of isolate.

According to our definitions, it would seem there is no difference between the terms.

I should have looked first.

 

[LeeJC]

Don't sweat it.
I'm not at all tetchy about anyone or anything said in this forum.
I just get tired of being mugged off by big organisations and the general approach of 'you're all a bit too stoopid to understand/deal with this' whilst appreciating things have to be aligned with the lowest common denominator.
What was it I read in the 18th Edition, qualified and competent or was it qualified or competent?
My background is ground electronics from 7.7vdc comms to 40kv Heavy Radar, with stop offs at datalinks/electronic warfare/missiles.
It certainly doesn't deem me qualified, but I'd be prepared to wager some cash against competent.
<That's lovingly referred to as a Mekon, it's the mercury arc rectifier out of a type 80 radar and it glowed a lovely blue.

 

[LeeJC]

Skilled person (electrically). - Person who possesses, as appropriate to the nature of the electrical work to be
undertaken, adequate education, training and practical skills, and who is able to perceive risks and avoid hazards
which electricity can create.

I'm definitely that, however I'm unaffiliated, unsubscribed and uninterested in any organisation who may deem me so....................for an associated fee of course.

 

[JohnW2]

Prior to a consumer unit replacement for example. As there is no intermediate isolator between the meter and the CU where is the safe isolation point to allow disconnection/connection of the tails? Only answer is removal of the Cut Out fuse, which can be done with DNO approval ...

Indeed, and that's how it always has been, when there is no isolator installed downstream of the meter

but which as previously suggested likely results in an enquiry from the supplier.

Maybe - but that enquiry, if it happens, can obviously simply be referred to the DNO. I would, however, have thought/hoped that there would be some interaction between DNOs and suppliers, so as to avoid the need for countless unnecessary 'enquiries'.

No I don't assume the meter has a means of 'safe' isolation. I suggest that the meter has a means of isolation which when contacting the supplier for a disconnection is utilised and deemed by them to be 'safe'.

As has been said, no matter what the supplier might think, few (if any)) of us here would be happy to trust our lives to such 'isolation' being 'safe'.

Interesting use of the phrase 'if necessary' ...

Yes, interesting. I;ve personally never heard of a case in which a supplier has consdiered the installation of a post-meter isolator to be 'necessary' - to the best of my knowledge, they only install such isolator (with or without charge) if that is resquested by a consumer.

I think there is probably a bit of a language issue here, such that where the diagram says "isolation switch .... if necessary", they probably really meant "If requested" (by consumer).

Kind Regards, John

 

[LeeJC]

Thanks for the reply John.
I've just been looking through the literature for the meter, and although it states the whole 100Amp Breaker to connect/disconnect. When reading the applicable standards from the meter literature, none of them appear in the 18th Chapter 53.

I'll get one installed because I deem it necessary and swallow the £158.25.................. still cheaper than an AFDD