Strange light switch wiring.

Pete67

I came across a odd installation yesterday, the lighting circuits are wired with 1.5sq T&E looped to the switch locations, and same from switches to each ceiling roses. Nothing wrong with that but whoever did the second fix wired the permanent live to L1, the neutrals to L2 and the switched live to the common terminals on all the switches. The CPCs go to a terminal in the backbox. Seems all wrong to me but it does work. Interested in your thoughts.

meercat

Pete67 wrote: »

I came across a odd installation yesterday, the lighting circuits are wired with 1.5sq T&E looped to the switch locations, and same from switches to each ceiling roses. Nothing wrong with that but whoever did the second fix wired the permanent live to L1, the neutrals to L2 and the switched live to the common terminals on all the switches. The CPCs go to a terminal in the backbox. Seems all wrong to me but it does work. Interested in your thoughts.

Are you sure the neutrals(blue wires) aren’t in fact strappers on 2 way switches. They shouldn’t be blue. I’d expect a trip switch to activate if the neutrals were connected to the light switch

Pete67

Nope, they are definitely the neutrals, none of these circuits have two way switching. I couldn't believe it either so I belled them out to the ceiling roses. There is 230V across L1 and L2 on each switch.

naughtysmurf

Are you sure your neutrals are actually neutrals?

Bonzo Delaney

Looks likely the "sparks" had no brown cable left in the van that day

Pete67

Yes, I separated them and verified continuity between one of the neutrals at the switch and the neutral terminal at the ceiling rose. Also the incoming T&E from the CU is visible in the attic befoew dropping down to the switch, and the brown goes to L1 and the blue to L2. All the neutrals are tied together in the L2 terminal, and the L out to the rose is in the COM terminal. And it does work.

Doolittle51

So they used L2 on the switch to join the neutrals together, instead of using a wago or terminal block?
When the switch is off, L2 & Common would be made, so switched live (to the lamp) is connected to neutral instead of permanent live.
Strange one alright!

Pete67

I should have said that the switch above switches three different lights in a kitchen, with separate cables from the switch to each rose. But the other switches are wired similarly, although most switch just one light. Only thing I can think of is that it was done to avoid using additional terminals to tie the neutrals together.

Bonzo Delaney

Is it possible to isolate L2 in a 2way switch ???? Surely the only way that set up could work

naughtysmurf

Doolittle51 wrote: »

So they used L2 on the switch to join the neutrals together, instead of using a wago or terminal block?
When the switch is off, L2 & Common would be made, so switched live (to the lamp) is connected to neutral instead of permanent live.
Strange one alright!

Looks like it, bit odd to say the least

Doolittle51

naughtysmurf wrote: »

Looks like it, bit odd to say the least

Maybe some kind of innovative technique to eliminate nuisance glowing on led bulbs even when they are switched off?
Or just a really scabby sparks, who doesn't want to fork out for a few wagos or terminal blocks!

Pete67

It does work, but is very strange. It's a relatives house, about 10 years old I'd say. He's wondering about the rest of the electrical installation now. Would this method contravene any of the wiring regs?

aido79

Bonzo Delaney wrote: »

Is it possible to isolate L2 in a 2way switch ???? Surely the only way that set up could work

They used L1 as the common so they don't need to isolate L2. When the switch is in the off the neutrals are connected to the switch wire and not the permanent live.

It's a strange way to do it just to avoid using a connector for the neutrals it would seem.

Pete67

Doolittle51 wrote: »

Maybe some kind of innovative technique to eliminate nuisance glowing on led bulbs even when they are switched off

I never thought of that, would be actually quite smart if that's the reason for it. Both sides of the lamp would be connected to N when off so definitely no nuisance glowing.

naughtysmurf

Pete67 wrote: »

It does work, but is very strange. It's a relatives house, about 10 years old I'd say. He's wondering about the rest of the electrical installation now. Would this method contravene any of the wiring regs?

It does & will work in the current set up but I doubt whoever wired it was ever told it was best practice, having said that I'm not up to date on the current regs, just seems wrong to me.

Bonzo Delaney

aido79 wrote: »

They used L1 as the common so they don't need to isolate L2. When the switch is in the off the neutrals are connected to the switch wire and not the permanent live.

It's a strange way to do it just to avoid using a connector for the neutrals it would seem.

Ah now It makes sense ....in a really strange way . Couldn't see the forest for the trees there.

Westernworld.

I couldn't think of anything wrong with it's operation or even testing

Bat**** crazy though