Poll: How Many Installation(s) do I have?

[JohnW2]

This question is stimulated by a discussion I'm currently having with BAS.

The electrical set-up in my house consists of an incoming 3-phase (3P+N) supply and a single 3-phase meter, but after that the several distribution circuits and DBs/CUs and countless final circuits are all single-phase. There are no 3-phase DBs or circuits. As far as the supplier is concerned, this is obviously just one supply/service (i.e. one 'account').

Would you consider my house as having one electrical "installation" (with a 3-phase supply), three separate electrical "installations" (each single phase) or more than 3 electrical "installations" (each CU/DB and its final circuits being an "installation")??

Kind Regards, John

 

[EFLImpudence]

Well, as we have discovered, the definition of voltage in Part 2 is not entirely accurate so I would say the same applies to the definition of installation.

I think you have one installation and one supply - and so does a block of flats.

 

[JohnW2]

Well, as we have discovered, the definition of voltage in Part 2 is not entirely accurate ....

To be fair, I suppose BS7671 is free to define voltages in any way it wishes for the purpose of the Standard. It does not claim to be presenting IEC (or any other 'recognised') definitions.

... so I would say the same applies to the definition of installation.

As I've said elsewhere, the BS7671 definition of "installation" is so vague and all-encompassing as to be totally useless. Anything from a switch+lampholder+bit of cable to a highly complex industrial electrical 'set-up' would satisfy that definition!

I think you have one installation and one supply ...

As you will be aware, that's how I've always thought of it. Unfortunately, if it is a single installation, with a 3-phase supply, then 530.3.4 (536.4.201 that is to be!) presumably does not apply - which seems to mean that all of my "CUs" are probably non-compliant because they don't contain 16kA devices (not that I'm losing any sleep over that non-compliance ).

.... - and so does a block of flats.

That's an interesting one. I suppose I would agree that "a block of flats" has one installation - but I'm also inclined to think that each of the flats within the block has its own separate installation.

Kind Regards, John

 

[EFLImpudence]

To be fair, I suppose BS7671 is free to define voltages in any way it wishes for the purpose of the Standard. It does not claim to be presenting IEC (or any other 'recognised') definitions.

Not really, as some electricians, registered, have to follow it, it cannot 'make up' things different to accepted practice - at least, not without noting it.

That's an interesting one. I suppose I would agree that "a block of flats" has one installation - but I'm also inclined to think that each of the flats within the block has its own separate installation.

That's back to the definition.

The building has one installation - definitely - and perhaps each flat does have its own installation.
So, do we need another word or can many installations be within one large installation - irregular fractals.

Maybe yours is three in one.

 

[JohnW2]

So, do we need another word or can many installations be within one large installation - irregular fractals.

Well, the latter is certainty the case with the BS7671 definition - any 'installation' as you or I would recognise it must contain countless 'sub-bits' that would satisfy the BS7671 definition of 'an installation'. However, if that's the way they want to do it, regs like 530.3.4 really must make it clear exactly what they are talking about - the definition in Part 2 is simply not enough.

Kind Regards, John

 

[ericmark]

As well as installation we have circuit, protected against overcurrent, if over a set current flow out of the circuit it disconnects, it is a protection device, so the installation is split into circuits, and under the division of installation heading it sights as one reason to split into circuits is to "(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation." so clearly it considers a RCD creates a circuit.

Having read the BS7671:2008 again I would say the installation is the system which in under the control of a person, so if we have a group of houses with a warden controlling what goes on, as with old age persons bungalows then all those bungalows are one installation, however without the warden then they would be many installations. I am looking at "Protective measures for application only when the installation is controlled or under the supervision of skilled or instructed persons" So the high voltage could be one installation, and the low voltage another installation within the same factory. Due to who has control.

So that group of bungalows is two installations one controlled by the DNO the other controlled by the warden.

My house also has a number of distribution units, in fact three, one only has two RCD's in it, the other two have main isolator and 4 MCB's each. The units were originally fuse boxes, and do not comply with the criteria to be considered as consumer units, they were made before the British standard was in force for the type testing of distribution units, because I am skilled that is not a problem even if installed like that today, however although we are skilled, I think we should really have our homes designed for ordinary persons to be in control.

I don't see a problem with BS7671 definitions, however I do see a problem where these definitions are not reflected in our laws, to my mind a FCU forms a circuit, and for anyone to declare in law it does not form a circuit means the law then has to define the word circuit, it is not restricted to electrics, what is a food preparation area? If you prepare your food in the dinning room, then that room is a kitchen, a kitchen does not need a sink or a cooker fitted. So when the units are stripped out of a room and there is not food preparation area it's not a kitchen, so you can wire like any other room, only when the work tops are fitted does it become a kitchen, by that time all sockets etc are installed. OK in England no longer a problem. But what I am saying is if laws use words like kitchen, circuit, installation, and competent, which have different definitions to BS7671 then not really up to BS7671 to change it is up to the law makers to define their words.

 

[JohnW2]

As well as installation we have circuit ...

We do, but that's a separate discussion. Whatever 'an installation' is meant to mean, I don't think there is any doubt that it can (and nearly always does) include multiple circuits.

Having read the BS7671:2008 again I would say the installation is the system which in under the control of a person, so if we have a group of houses with a warden controlling what goes on, as with old age persons bungalows then all those bungalows are one installation, however without the warden then they would be many installations.

That's an interesting view, and one which I think could result in some anomalies, but we have no idea as to whether or not that is what BS7671 intends.

My house also has a number of distribution units, in fact three, one only has two RCD's in it, the other two have main isolator and 4 MCB's each. The units were originally fuse boxes, and do not comply with the criteria to be considered as consumer units, they were made before the British standard was in force for the type testing of distribution units, because I am skilled that is not a problem ....

Are you sure about that? As I see it, and strange/illogical though it may be, if "an installation" is not under the control of an "ordinary person" (i.e. if it is under the control of a 'skilled' person), then 530.3.4 does not apply, which seemingly prevents one taking advantage of the provision which avoids the need for 16kA devices.

Kind Regards, John

 

[JohnD]

How many full stops are there in a bottle of ink?

 

[JohnW2]

How many full stops are there in a bottle of ink?

A lot.

Do I take it from your vote that you do not think my CUs (well, the devices in them) are technically compliant?

Kind Regards, John

 

[JohnD]

three million, two hundred and eighty-five thousand, five hundred and twelve

or

one very big one.

 

[JohnD]

My house also has a number of distribution units, in fact three

And of course, one Main Switch to isolate everything?

 

[JohnW2]

And of course, one Main Switch to isolate everything?

BAS would probably say that it was several "installations", so that each of them could have its own 'single point of isolation'!

When I got the man replacing my meter (who seemed sensible, intelligent and competent) to fit an isolator, he asked me why I wanted it, since I already had three up-front TD RCDs. The real reason was in case I ever needed to replace any of those RCDs, but (on the basis that I regard it as a single "installation") told him that it was 'required' for compliance with BS7671. His reply was "How daft"

Kind Regards, John

 

[scousespark]

under the division of installation heading it sights as one reason to split into circuits is to "(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation." so clearly it considers a RCD creates a circuit.

and under the division of installation heading it sights as one reason to split into circuits is to "(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation." so clearly it considers a RCD creates a circuit.

An RCD does not create a circuit as it does not produce voltage or current.

Having read the BS7671:2008 again I would say the installation is the system which in under the control of a person, so if we have a group of houses with a warden controlling what goes on, as with old age persons bungalows then all those bungalows are one installation, however without the warden then they would be many installations

I don't see how a number of dwellings can be regarded as a single installation because a warder (or any individual) has control of the properties.
Surely 3 bungalows is 3 bungalows and therefore 3 installations.

Out of interest, what makes you a skilled person in the scenario you stated?

 

[JohnW2]

An RCD does not create a circuit as it does not produce voltage or current.

I agree that an RCD does not create 'a circuit' (per BS7671 definition), but not for the reason you give. The BS7671 definition is that a circuit consists of an assembly of electrical equipment sharing a common OPD. An assembly of equipment sharing a common MCB, RCBO or fuse (but not an RCD) therefore 'creates a circuit' per that definition, even though none of those devices "produce voltage or current".

I don't see how a number of dwellings can be regarded as a single installation because a warder (or any individual) has control of the properties. Surely 3 bungalows is 3 bungalows and therefore 3 installations.

Indeed. As I hinted before, I find it hard to see that as a workable definition. That doesn't alter the fact that the BS7671 definition of "installation" is totally unhelpful!

KInd Regards, John

 

[ericmark]

Single point of isolation is I would say drawing the DNO fuse. In my house the fuse boxes are in the garage, which is normally locked, so if the fire man wanted to isolate power then pulling the DNO fuse which is located from a box outside would be the logical way, they would not hang around while I found the key.

For non emergency isolation the two RCD's are next to each other so very easy to operate both together.

The single point of isolation does separate the flats and bungalow, with a block of flats there is likely one point where you could isolated, but with a set of bungalows likely multi-points so I can see how the flats are one installation and bungalows many installations, however in the sub station likely there will be a single point of isolation for whole road, so using that at the definition does not really make sense.

I start to look at other installations, if I consider the gas terminal at Point of Aye that I worked on, there was no real point where you could split it into separate installations even though the site was large. However working at Jeyes in Mold they were using around 10 units which could have easy have been and in fact were sold off as separate units, so it would be considered as a least 10 installations as not really connected.

If I think about the Steel works, then it had some parts which one could consider separate as with Jeyes, but there were 4 power stations, the main one, had control of all power both in and out of all buildings and power stations and to and from national grid, it was a true power station, steam, air, gas, and electric all controlled from one central point, because of this interlinking of the services it is likely it could all have been considered as one. However covering more than one square mile personally I would class each building as an installation.

In fact if we consider what is entered on an installation certificate then that seems a more reasonable way to define it. So re-thinking it all, I would say it is all down to how many installation certificates cover the house, if you have 5 certificates then it is 5 installations, even if only one consumer unit.

So my house has one installation certificate so it's a single installation, my mothers house has three installation certificates, so it is two or three installations even if the second consumer unit is fed from the primary one. I did not look when re-wired if the kitchen and wet room was tested and inspected or if it was considered as being covered by the original testing and inspecting.

As to when no installation certificates have been raised or found, and the property has an EICR coving all, if then we would consider the EICR as replacing the installation certificate as far as defining how many installations I don't know, but I would say does not really matter if a installation certificate or an EICR these documents define what is in the installation. Minor works certificates don't count.

As to finding some regulation to support this idea that's something else, but when one considered how hard to define using any other method, it seems the certificates method would still work what ever the unit was, an installation is what is inspected and tested with a single certificate.

So how many installation certificates cover the house? if more than one, I will change my vote.