Supply from 2 MCB's in one backbox...

[Guitarist]

Ok, we all see it on lighting circuits when there is one supply for upstairs and one for downstairs (2-way lighting). How many of you...

1) Rewire so that both lighting circuits are on 1 supply

2) Just ignore it, as the regs say that having upstairs and downstairs on separate supplies makes a property safer (all lights out, fall down stairs etc.)

3) Leave as is (for above reason), but put a warning label in the box stating 2 supplies...

 

[PC Electrics]

option 3 generally

 

[sedgy34]

not me your honour!

 

[GLENNSPARK]

well its a scenario i`m sure we`v all come across....the borrowed neutral that is......however in this case...should be all on one MCB....as for lighting all on one circuit or fed from one MCB....just note it.....its a bit like no CPC in lighting cable/s....just note it....but check theres no class 1s of course...

 

[Richard]

Option 3. So long as you make it clear I can't really see a big problem. In com/ind you see it all the time. If i'm wiring from scratch though, i'll always make sure to keep only 1 circuit in each accessory.

Rich

 

[Plonker 3]

Cant see a problem with it as long as it the same phase within the box, as safe isolation of supply should be carried out and found by anyone who thinks they have correctly isolated a feed.

Although option 3 doesn't hurt to do it.

 

[kingeri]

Surely to comply with the requirements for safety (i.e. not having whole house plunged into darkness) having two circuits in a two gang switch is unavoidable (upstairs and downstairs lights), or do people now use two one gang switches next to each other? Any spark worth his salt double / triple checks when working on lighting circuits, especially two-way arrangements.

 

[mark ju]

Option 3 i think. As already stated happens all the time in commercial/industrial applications, and i know thats not quite the same as domestic which is what you queried,but its good practice to mark it as such.

 

[Guitarist]

No borrowed neutral Glenn, just 2 cables into one 2 gang switch, each on a different MCB. Bungalow, so I'm gonna rewire so both on same breaker. If I couldn't easily, I would put a label inside. I know that all electricians would test all cables, but a homeowner may only test one and assume it was all dead.
Just wondered what the general consensus is.

 

[GLENNSPARK]

No borrowed neutral Glenn, just 2 cables into one 2 gang switch, each on a different MCB. Bungalow, so I'm gonna rewire so both on same breaker. If I couldn't easily, I would put a label inside. I know that all electricians would test all cables, but a homeowner may only test one and assume it was all dead.
Just wondered what the general consensus is.

oh well in that case i would certainly b getting em on one supply MCB...for the good reasons you point out guitar....but its all about them being electrically seperated..hence the borrowed neutral thing.....but at the same time....dont forget that a switch front is an enclosure..together with its knockout/appleby box....so anyone going in there would be a competent person?....

 

[GLENNSPARK]

but if its like an upstairs radial final feeding lamps....but is on one of those switches in that 2 gang at the bottom of the stairs....i mean usually the landing lamp would be 2 wayed with the hallway....on the downstairs circuit...

 

[Adam W]

If they were on different phases such as in an office I'd put a 400v sticker on it. I suppose it couldn't hurt to leave a note in the switch box provided it's not going to catch fire, but I'd probably go for option 2; as mentioned anyone working on it should know to exercise caution with upstairs/downstairs lighting and you have to draw the line somewhere - you don't stick warning labels on 3 plate lighting saying there is a live supply even when the light is switched off.

This arrangement seems needlessly ambiguous in a bungalow because it hasn't got an upstairs. Better to have them on the same circuit IMO.

 

[Guitarist]

If they were on different phases such as in an office I'd put a 400v sticker on it. I suppose it couldn't hurt to leave a note in the switch box provided it's not going to catch fire, but I'd probably go for option 2; as mentioned anyone working on it should know to exercise caution with upstairs/downstairs lighting and you have to draw the line somewhere - you don't stick warning labels on 3 plate lighting saying there is a live supply even when the light is switched off.

This arrangement seems needlessly ambiguous in a bungalow because it hasn't got an upstairs. Better to have them on the same circuit IMO.

Agree with you Adam. I didn't wire it, just found it when seeing which lights were on which MCB.

 

[adamh]

I dont see any problem.. what about grid switches for banks of lighting etc.. as people have said if you do your safe isolation then its dead , never assume always prove it.