2 consumer units?

[JohnW2]

Only if you deliberately decide to make it a snag by deliberately classifying two separate CUs and their two totally unrelated sets of final circuits as a single installation.

I don't intend to re-open the discussion about the definition of "an installation", but ....

....Avoiding that perversity and classifying what you have as two assemblies of associated electrical equipment having co-ordinated characteristics to fulfil specific purposes means that you don't need an isolator before the CUs.

In this case, it surely has a lot more to do with safety and common sense than having anything to do with semantics, definitions or regulations? In an emergency (and maybe 'a panic'), it makes sense for a householder to know that there is a single switch will will shut down 'everything electrical' in his/her house (regardless of 'the number of installations'), rather than having to think about which one to use (assuming that they actually know/realise that there is more than one), doesn't it??

Kind Regards, John

 

[bernardgreen]

makes sense for a householder to know that there is a single switch will will shut down 'everything electrical'

makes sense for emergency services to have access to a recognisable single switch

 

[JP_]

this won't be a long term thing, just so we won't have to reqire the whole house before finishing the extension.

 

[JohnW2]

makes sense for emergency services to have access to a recognisable single switch

Well, yes, them too - but they are probably less likely to understand the installation (or installations!) than the householder/occupant. If they come across a CU with a main switch, they might well think that it shuts off everything electrical in the property - but there might be an isolator elsewhere, which also supplies another CU (or CUs) which are also 'elsewhere'.

If they wanted 'to be sure', they would locate the cutout and pull the fuse(s) - maybe that's what they do do?? (or, quicker, just chop the cables leaving the cutout!)

Kind Regards, John

 

[JohnD]

classifying two separate CUs and their two totally unrelated sets of final circuits as a single installation.

I don't see that it is perverse, foolish, wicked or unsafe to have one main switch in a house, that turns off everything with one click of a switch.

 

[ban-all-sheds]

I don't see that it is perverse, foolish, wicked or unsafe to have one main switch in a house, that turns off everything with one click of a switch.

It is if you have made that decision and then regard it as a problem.

To deliberately refuse to recognise what the definition of an electrical installation is and "thus" find that you are "required" to do something you regard as a snag is perverse.

 

[ban-all-sheds]

I don't intend to re-open the discussion about the definition of "an installation",

It's an assembly of associated electrical equipment having co-ordinated characteristics to fulfil specific purposes.

You are wise to not intend to try and pretend that a CU and its final circuits cannot be an installation if there is another CU and another set of final circuits, or that it is impossible for more than one installation to exist, as neither of those are even hinted at by any regulation, let alone stated.

In this case, it surely has a lot more to do with safety and common sense than having anything to do with semantics, definitions or regulations? In an emergency (and maybe 'a panic'), it makes sense for a householder to know that there is a single switch will will shut down 'everything electrical' in his/her house (regardless of 'the number of installations'), rather than having to think about which one to use (assuming that they actually know/realise that there is more than one), doesn't it??

If they don't know, or don't want to know, then they can still flick the switches in more than one CU.

Safety and common sense also means that when you move into a house you take the trouble to see which circuits are associated with which breakers/fuses, and you take the trouble to find the water stopcock, and see that it works, and if you find other valves in pipework you see what they do, and you take the trouble to find where to turn of the gas and/or the oil, and check that that works.

The fireman's switch seems like a red herring, as nobody installs proper ones on the outside of their houses, and there must be countless properties which would not by your standards "require" a single isolator and yet don't have them. If safety and common sense were the drivers for requiring a main switch then it would not be limited to households and ordinary persons.

But please note that I wrote what I did in response to Bernard saying that there's a snag to having 2 CUs. There isn't, unless you want there to be one.

 

[bernardgreen]

But please note that I wrote what I did in response to Bernard saying that there's a snag to having 2 CUs. There isn't, unless you want there to be one.

Obviously BAS has little if any experience as fire fighter of dealing with a fire in a house and the hazards that sometimes prevent fire fighters entering a building until it has been made electrically safe. In reality the prevention is bypassed and the firefighters do enter if theree are persons reported as being in the house.

 

[ban-all-sheds]

Why is a main isolator not required when there is more than one installation in a premises?

 

[JohnD]

When a house has one incoming service and one meter with some stuff running off it, it is perfectly sensible for the man on the Clapham Omnibus to call the stuff "an installation." Not "some installations." And to have one Main Switch.

The idea that you would have a main switch marked "Main Switch (for the cooker and freezer,)" "Main switch (for the shed and outdoor lights.)" "Main Switch (for the house sockets and most lights,") "Main Switch (for the loft conversion, except the extractor fan.)" is obviously silly. You would have switches on the various CUs, and only one "Main Switch" for everything in the house and garden.

 

[JohnW2]

Why is a main isolator not required when there is more than one installation in a premises?

As you know, in my opinion (whatever definition BS7671 may choose to offer), you are talking about a situation which does not exist - at least in terms of common sense and everyday language.

All the plumbing within one dwelling, one factory or whatever is, IMO, that dwelling's or factory's (one) plumbing installation.

All the built in heating within one dwelling, one factory or whatever is, IMO, that dwelling's or factory's (one) heating installation.

All the fixed electrical wiring/equipment within one dwelling, one factory or whatever is, IMO, that dwelling's or factory's (one) electrical installation.

Kind Regards, John

 

[JohnW2]

Safety and common sense also means that when you move into a house you take the trouble to see which circuits are associated with which breakers/fuses, and you take the trouble to find the water stopcock, and see that it works, and if you find other valves in pipework you see what they do, and you take the trouble to find where to turn of the gas and/or the oil, and check that that works.

I take it that you have never experienced being in a mad panic, and fearing for your life, when something catastrophic happens in your home?

Kind Regards, John

 

[ban-all-sheds]

When a house has one incoming service and one meter with some stuff running off it, it is perfectly sensible for the man on the Clapham Omnibus to call the stuff "an installation." Not "some installations." And to have one Main Switch.

The regulations are full of requirements and definitions which would read like the service manual for a Tibetan starship to TMOTCO.

The idea that you would have a main switch marked "Main Switch (for the cooker and freezer,)" "Main switch (for the shed and outdoor lights.)" "Main Switch (for the house sockets and most lights,") "Main Switch (for the loft conversion, except the extractor fan.)" is obviously silly.

It probably is.

But that's the first time I've seen mention of that scheme, so who was the obviously silly person who wrote that?

You would have switches on the various CUs, and only one "Main Switch" for everything in the house and garden.

Just read the definition of Electrical Installation and tell me where it even hints at more than one being forbidden.

 

[JohnW2]

Just read the definition of Electrical Installation and tell me where it even hints at more than one being forbidden.

I can't speak for JohnD but, as I've said more than once, in this thread I'm talking about common sense and safety, not BS7671 definitions or BS7671 regulations.

Even if there were no relevant regulation in BS7671, I would still say that it makes total sense to have a single switch which shuts off 'everything electrical' within a dwelling or other premises - so I'm not in the slightest interested in your use of BS7671 definitions to reach the conclusion that a single, say, dwelling does not necessarily to have a single point of isolation in order to be compliant with BS7671.

Kind Regards, John

 

[ban-all-sheds]

As you know, in my opinion (whatever definition BS7671 may choose to offer), you are talking about a situation which does not exist - at least in terms of common sense and everyday language.

As you know, it is only the definition in BS 7671 which carries any weight.

All the plumbing within one dwelling, one factory or whatever is, IMO, that dwelling's or factory's (one) plumbing installation.

All the built in heating within one dwelling, one factory or whatever is, IMO, that dwelling's or factory's (one) heating installation.

All the fixed electrical wiring/equipment within one dwelling, one factory or whatever is, IMO, that dwelling's or factory's (one) electrical installation.

I know that you are not so stupid as to really think that no matter how big, and how complex the plumbing or fixed electrical wiring/equipment is it can never reasonably be considered as more than one installation, nor that it has to be considered as one and that therefore there has to be a single switch to turn everything off.

So why? Why insist that under no circumstances can there possibly be more than one assembly of associated electrical equipment having co-ordinated characteristics to fulfil specific purposes in any location?