2-Gang switch on different circuits

[DaveC]

My house is an old timber-framed building with a modern extension. I want to add some extra switches to the lighting circuits in the old part of the house where good sites for new wiring and switches are limited.
There are multiple lighting circuits from the CU. At one particular point where two of the circuits come close together I'd like to add a switch to each circuit. It would be really convenient space-wise to install the two switches as a single two-gang unit. I know this is electrically feasible but I do feel slightly uneasy about it - mainly about isolation issues. Can anyone please advise me about the regulation aspects of doing this and/or any conventions for marking the wiring to show what's going on?
Thanks.

 

[conny]

What will these switches control?

Not advisable to do this as if you isolate the circuit you are working on the other will still be 'live' and it is quite easy to 'accidently' come into contact with.
Also looking to the future if someone else works on the switch how will they know one side will still be live.

My advice is to forget this idea. (And yes, there probably is a rule/regulation somewhere.)

 

[securespark]

You could use a grid switch that has a warning label on the grid.

That way, you are aware of the wiring arrangement before you access any live parts.

 

[GaryMo]

What will these switches control?

Not advisable to do this as if you isolate the circuit you are working on the other will still be 'live' and it is quite easy to 'accidently' come into contact with.

You shouldn't be working near live terminals

Also looking to the future if someone else works on the switch how will they know one side will still be live.

Because the electrician would have measured voltage at the terminals? Follow safe isolation procedures. If you can't do that then you've no right playing around with electrics

My advice is to forget this idea. (And yes, there probably is a rule/regulation somewhere.)

How many times have you seen 2 or 3 gang switches controlling downstairs hallway and upstairs landing lighting, with downstairs and upstairs lighting on different circuits?
Please find me a regulation which directly contravenes this arrangement but bare in mind, safe isolation procedures would have been followed upon removal of the faceplate screws.

You could always do as Securespark suggested and leave a courtesy warning notice for a belt and braces approach

 

[Lectrician]

It is a very common practice.

You see it in almost every house.

I see nothing wrong with doing this.

 

[DaveC]

Thank you all for your replies - some varying views here.
My scenario is pretty much like GaryMo cites - upstairs/downstairs/landing lights.
Given my space constraints I think I'll go ahead with the 2-gang switch and put a warning label inside the box.
Thanks again for all your responses.

 

[ColJack]

You could always do as Securespark suggested and leave a courtesy warning notice for a belt and braces approach

actually, it's not a courtesy, it's a regulation ( or at least was in the 16th, don't have a copy of the 17th yet.. )

used to be 514-11-01.
basicaly, if there is more than one supply in an enclosure, then it needs a durable lable stating as such, with the location of each supply marked on it, unless it's obvious where they come from ( which if you only have one CU then they both come from there.. )

 

[GaryMo]

If both circuits are fed from the same consumer unit then compliance is met due to the main isolator. In that instance, no warning label is required. How many labels have you seen where up and down lighting circuits enter the same enclosure?
The only time I can see 415-11-01 not being met (in this situation) is when each circuit is fed via a separate consumer unit and a single point of isolation doesn't exist before the two consumer units.

 

[holmslaw]

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[GaryMo]

Voltage warning labels only required when nominal voltage to earth is greater than 230v. Even when 2 phases enter an enclosure nominal voltage to earth is still 230v (LV system).

 

[conny]

Garymo,

conny wrote:
What will these switches control?

Not advisable to do this as if you isolate the circuit you are working on the other will still be 'live' and it is quite easy to 'accidently' come into contact with.


You shouldn't be working near live terminals

are you telling me you have NEVER accidently got a belt? or know anyone who hasn't?

conny wrote:
Also looking to the future if someone else works on the switch how will they know one side will still be live.


Because the electrician would have measured voltage at the terminals? Follow safe isolation procedures. If you can't do that then you've no right playing around with electrics

I quite agree but who said it will be a spark working on it? Even in these days of 'Part P' etc other 'trades' will have a go at something they are not qualified to do and even sparks have been known to forget to check something.

conny wrote:
My advice is to forget this idea. (And yes, there probably is a rule/regulation somewhere.)


How many times have you seen 2 or 3 gang switches controlling downstairs hallway and upstairs landing lighting, with downstairs and upstairs lighting on different circuits?
Please find me a regulation which directly contravenes this arrangement but bare in mind, safe isolation procedures would have been followed upon removal of the faceplate screws.

If you read the first sentence of my post it asks what will the switches control. If I had known he was referring to two way switching then I wouldn't have asked this question but unfortunately I am not psyhcic (sp) I also said 'probably', not 'There is a rule/regulation'.
I am happy to accept criticism or being corrected when it is justified but sarcasm is the lowest form of wit and a lack of understanding of what you have read.

 

[GaryMo]

My post wasn't written to be sarcastic, sorry if you took it any other way.
I do however stand by all points I made in it and believe compliance with the electricity at work act and BS7671 would be met.

 

[Spark123]

Think you mean the Electricity at Work Regulations and the Health and safety at work act?

Voltage warning labels only required when nominal voltage to earth is greater than 230v. Even when 2 phases enter an enclosure nominal voltage to earth is still 230v (LV system).

The reg now just says Nominal voltage, in 3 phase between conductors this is 400v.
The old reg in the 16th referred to Uo which is phase to earth.

 

[GaryMo]

Think you mean the Electricity at Work Regulations and the Health and safety at work act?

Yes

Voltage warning labels only required when nominal voltage to earth is greater than 230v. Even when 2 phases enter an enclosure nominal voltage to earth is still 230v (LV system).

The reg now just says Nominal voltage, in 3 phase between conductors this is 400v.
The old reg in the 16th referred to Uo which is phase to earth.

I've just read the regulation relating to warning notices for voltage (514.10.1) and you're quite correct. I didn't realise this had changed from the 16th edition.

 

[holmslaw]

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