Isolator between meter and CU

[robo83]

Had a discussion with a friend regards an isolator installed between the meter and consumer unit. The meter is otherwise of the wall and tails enter through the wall into a Henley block. Then the Henley block feeds 2 CUs

What's your thoughts please as I want to install one and he is telling me it's not required.

 

[snowhead]

What 's the reason for wanting to install one?
Who would install it ?

 

[Octopus]

This is all about the old chestnut of single point of isolation.....

 

[robo83]

The electrican I work with said it's not needed as the main isolator is isolation point for that board.

Exactly as Murdoch mentioned. As two boards it would need single point?

 

[Des 56]

The electrican I work with said it's not needed as the main isolator is isolation point for that board.

Exactly as Murdoch mentioned. As two boards it would need single point?

1. A single point of isolation should be provided for an installation
2. A property can consist of more than one installation
eg General use board, shower or garage or storage heating with separate boards

The aim is to satisfy No1
Good practice could combine them all via one isolation point
The electrician is correct and you are employing good practice by improving the set up by having one means of isolation for the "property" as a whole

 

[davesparks]

How can you say that there is more than one installation in a domestic property? It's all connected to the same origin and the refs define an installation by the origin not the number of boards.

 

[Des 56]

How can you say that there is more than one installation in a domestic property? It's all connected to the same origin and the refs define an installation by the origin not the number of boards.

The regs define an installation by the definitions listed below
The number of boards do not define an installation
The number of boards is neither here nor there
The property whether its domestic commercial or industrial can have multiple installations,all fed from a common origin
Installations are not defined by the origin

Installation
An assembly of associated electrical equipment having co-ordinated characteristics to fulfil specific purposes


Electrical Equipment
Any item for such purposes as generation.conversion.transmission.distribution or utilization of electrical energy,such as machines,transformers,apparatus,measuring instruments,protective devices,wiring systems,accessories,appliances and luminaires

Co-ordinated charecteristics
The IET
A particular type of distribution board comprising a type-tested co-ordinated assembly for the control and distribution of electrical energy incorporating manual means of double-pole isolation on the incoming circuit(s) and an assembly of one or more fuses, circuit breakers, residual current operated devices or signalling and other devices

There is no mention of origin in any of the definitions,however,there is definition of what comprises an installation

Conclusion
A property can have more than one electrical installation
The installations shall have a means of double pole isolation

 

[Des 56]

After posting my reply I looked elsewhere for some back up for my opinion
I do not have the guidance notes to check the validity of what is copied and pasted below
Maybe someone could check it is still current
Its copied from a post on the IET

IEE Guidance Note 2 - "Isolation & Switching", p.40

"It is permitted for a dwelling to have more than one electrical installation. Therefore one 'main switch' is not required to isolate all consumer units simultaneously provided the consumer units have an integral main switch.

"This situation frequently occurs when an additional consumer unit is added, e.g. to supply an electric shower. Regulation 537.2.2.6 requires each device used for isolation to be clearly identified by positional or durable marking to indicate the installation it isolates."

 

[Octopus]

Just a bit of a curved ball... How would you achieve this with PV ?

 

[Midwest]

With reg 537.1.3 & 537.1.4, I would say the requirement would depend on the installation. If the two CU's were adjacent, then the it would not require a single isolator (as long as the CU's main switches comply).

If the two CU's were not adjacent, or it was not obvious, then a single isolator would be required.

 

[westward10]

I have no idea why people try to find a reason not to provide a single point of isolation on a rudimentary domestic installation. It is an excuse for housebashers to lash in so called shower boards.

 

[Ian1981]

If your fitting a 2nd cu in a domestic installation then is a common isolator not being fitted anyway when fitting Henley blocks?
Or is the fuse being pulled and the seal removed?

 

[Ian1981]

Just a bit of a curved ball... How would you achieve this with PV ?

The installation requires a warning label stating more than one source of supply

 

[snowhead]

Just a bit of a curved ball... How would you achieve this with PV ?

The PV is dead as soon as the board / C.U it's fed into is off.

 

[Des 56]

I have no idea why people try to find a reason not to provide a single point of isolation on a rudimentary domestic installation. It is an excuse for housebashers to lash in so called shower boards.

I agree entirely with your opinion
The opening post was asking for opinions of an argument about regulation requirements,I gave of my opinion as to what is required

Another opinion concerning what is required was given by davesparks

My other postings were trying to find out which is correct

We can all agree on best practice that we may require for our own work
It is also worth knowing what the regs require

 

[Wilko]

I have no idea why people try to find a reason not to provide a single point of isolation on a rudimentary domestic installation. It is an excuse for housebashers to lash in so called shower boards.

I'm still looking for an amd3 version of rec2 (say) or am I overthinking this?

 

[westward10]

Those quoting an installation being more than one installation when no single means of isolation is provided how do you go about doing EICRs. The Report asks for details of the installation in the singular so if there are three boards and no single means of isolation do you compose three Reports for your three installations.

 

[Octopus]

^^ in a word - no

 

[Ian1981]

What do the regulations say on the matter?
Working away so have no books.

 

[westward10]

What do the regulations say on the matter?
Working away so have no books.

About what.