Is this acceptable....? (got my doubts)

[sythai]

Domestic property with extension, 1 x cu supplying extension and exisiting cu supplying house... both fed from same single phase cut out.

2 way lighting between extension an existing house, and at one of the 4 gang switches there are 2 different circuits in there one from extension cu and one from existing cu.... is this ok ? Neutrals all ok and not mixed up, but no labelling stating 2 different circuits ? Wouldnt normally have done it this myself

Many thanks,

Sy

 

[Andyfm]

Sounds OK -if as you say thers no mixed neutrals

 

[sythai]

Thanks Andy, should it normally be labelled up somewhere or even marked at cu ...?

 

[mnmwill]

I think I would have to put a label somewhere, possibly on the CU, stating that there are two different circuits at the switch and note the location of the switch. Mr diy may decide to change said switch and think its isolated cos he turned off the MCB.

 

[Sparky Ninja]

You could argue that it's in conflict with section 314. I feel that it should be, however the section doesn't say word for word, anything that would back it up solid.

 

[davelerave]

it's not good practise anyhow


- the 2 circuits same box

- and the 'crossover' between the extension and main house wiring

 

[Deleted member 9648]

I'ts quite normal to have two circuits in one switch box....(upstairs/downstairs 2 way).....however in this case they are fed from two different CU's. I think a notice provided at the intake would be sensible,and also a notice stating there is more than one point of isolation for the entire installation.
Got talking to a guy at a wedding last week and he was telling me how he bought a new shiny chrome 2 gang switch for the bottom of his stairs,no problem changing that he thought as he turned off the downstairs lighting mcb...(you can guess where this is going)....I then had to listen to the inevitable story of him being 'thrown across the room' as of course the upstairs circuit was also present in said switch.............This is why we have voltage testers and safe isolation proceedures I was very pleased to inform him.

 

[Doug]

The ESC says:

Does the requirement for a warning notice in accordance with Regulation 537.2.1.3 apply to a two-gang light switch fed by two separate circuits in a domestic situation?

Yes, although it is recognised that the requirement may be difficult to comply with in some situations. The Forum intends to raise this issue with the BS 7671 Committee.

(17th Edition Guidance | New or Rewired Domestic and Similar Installations)

Obviously it is more serious if they are supplied by 2 separate CUs as there is not even a 'single point of isolation' from using a CU main switch. Warning labels on both CUs would help.

 

[davelerave]

I'ts quite normal to have two circuits in one switch box....(upstairs/downstairs 2 way).....however in this case they are fed from two different CU's. I think a notice provided at the intake would be sensible,and also a notice stating there is more than one point of isolation for the entire installation.
Got talking to a guy at a wedding last week and he was telling me how he bought a new shiny chrome 2 gang switch for the bottom of his stairs,no problem changing that he thought as he turned off the downstairs lighting mcb...(you can guess where this is going)....I then had to listen to the inevitable story of him being 'thrown across the room' as of course the upstairs circuit was also present in said switch.............This is why we have voltage testers and safe isolation proceedures I was very pleased to inform him.

i always assumed it was bad practice-i normally use a 'dual box' if 2 circuits' meet'

oir else separate the switches altogether

 

[Deleted member 9648]

Never heard it is bad practice and cant remember the last time I saw two separate switches in this situation.

 

[sythai]

Thanks for all your feed back.... going to mark up each cu with details just to be safe