3 gang, Two-way Light Switch has two circuits

[Dave Jenkins]

Ey up,
Did a quote for re-wiring a kitchen. That was straightforward enough but the client wanted replacement dimmer switches fitting to an existing 3 gang, light switch. OK, easy enough, but he's had an extension to the back of the house providing a large dining area off the kitchen. Whoever did the electrical work, ran the light circuit for the extension lights from the kitchen ring main (stepped down via 3A FCU), but then provided two way switching back to the existing kitchen light switch.
Now, I've never come across lighting configured that way before - not what I'd have done, but the light switch now contains a connection to the kitchen ring main (via FCU) and the downstairs lighting circuit.
Again, not what I'd have done, but is it wrong?? What does the collective think??

 

[Deleted member 9648]

Nothing wrong with that at all, circuits should be properly documented on a schedule at the DB as always. Some might argue that a DIYer would be at risk by just isolating lighting circuits, but anyone who cant or wont follow safe isolation procedure shouldn't be touching it at all. A common gripe you hear from DIYers is getting a belt from the 2 gang switch at the bottom of the stairs because they only switched off the downstairs lighting mcb !

 

[The Ghost]

Separation of circuits. I would not be happy with that sounds like an accident waiting to happen. If there is a supply from the spur providing power to two rooms that should be sufficient for both. Clearly there is the danger of switching off the power (you think) and getting electrocuted. I doubt a diy person is going to say "ah....just a quick check on the EIC schedule of circuits to ensure there are not two power supplies so that I can safely isolate" If I have understood you correctly that is. I read it about five times as I could not beleive what I at least think I was reading. Perhaps I have missed something? It should be labeled at least, I think re-reading I can see that it is not as bad as I first thought. Stating (the label) there are two different power supplies. I think I would have separated the switches.

 

[Wilko]

Hi V - it's relatively common to have two circuits in one containment in a house, eg a two way stairs light and hall light. I agree it is not straightforward, but that's why the safe isolation procedure is so important .

 

[Octopus]

No problem as far as I'm concerned .........

 

[The Ghost]

Requires label.

 

[Deleted member 9648]

Requires label.

Where does it say that?

 

[Colin Jenkins]

Where does it say that?

BS 7671 A3 Regulation 514.1.1. Two separate supplies in one enclosure should always have a warning label.

Best regards,

Colin Jenkins.

 

[Deleted member 9648]

BS 7671 A3 Regulation 514.1.1. Two separate supplies in one enclosure should always have a warning label.

Best regards,

Colin Jenkins.

It's not two separate supplies, it's two circuits from a single source of supply.

 

[The Ghost]

Vortigerns annals of common sense and professional courtesy. Put it inside the switch.

 

[Deleted member 9648]

Vortigerns annals of common sense and professional courtesy. Put it inside the switch.

Fine with that.

 

[happysteve]

I think perhaps you mean 514.11.1?

514.11 Warning notice: isolation
514.11.1 A notice of such durable material as to be likely to remain easily legible throughout the life of the installation in accordance with Regulation 537.2.1.3, shall be fixed in each position where there are live parts which are not capable of being isolated by a single device. The location of each disconnector (isolator) shall be indicated unless there is no possibility of confusion.

537.2 Isolation
537.2.1.3 Where an installation or an item of equipment or enclosure contains live parts connected to more than one supply, a durable warning notice shall be placed in such a position that any person before gaining access to live parts, will be warned of the need to isolate those parts from the various supplies unless an interlocking arrangement is provided to ensure that all the circuits concerned are isolated.​

I suppose you could argue that, in the example above, the live parts are capable of being isolated by a single device - that being the main switch - as there is only one supply.

I've seen a 2G light switch that is fed not only from two separate circuits, but also two separate sub-boards (on two different phases). In a commercial/industrial setting, I think common courtesy more than anything else might make a small warning notice appropriate.

I can't imagine many householders would be happy with a sticky label under their landing/hallway light switch, though! By all means stick one on the inside, if you like.

 

[Deleted member 9648]

Indeed, as I said in post #9 those regulations are intended for more than one source of supply, not more than one circuit from the same source of supply, clearly as I got a creative there are those who don't understand the difference.
If there was a requirement for such labelling in the case of multiple circuits within an enclosure there would be silly labels on most domestic stairs switches, and grid switch isolation panels for kitchen appliances.