2 way switching help

[b21playa]

Hi all

Need some help on 2 way switching.

The house is a terraced house which has a through lounge. There are 2 lights and 3 switches.

- first switch is as you walk in, 1 gang to control the front light only
- second switch mid-way along the length, 2 gang switch to control front and back light
- third, opposite wall of seconds switch, 2 gang to control back light and upstairs landing light.

Now the problem is the 2 way switching for the 2 downstairs lights dont work. Looking at the wiring, there is a 3core + earth from the 1st switch to the 2nd switch. Then only a twin + earth from the 2nd to the 3rd. This all worked a while back, but electrics tripped one day and never worked again.

I have done a continuity test on the 3core + earth and it is dead on one of the cores, but its not shorted to any of the other cores or earth.

I guess this is where the problem has started from.

Any ideas on what could have caused it and if there is anyway I could get this to work with Twin + earth?? The whole lounge has been redecorated so I dont want to re-wire it

Thanks in advance

 

[pjcomp]

What exactly isn't working, and why do you think the switch is the problem? You say it did work, then it didn't. So what changed? If the lighting circuit tripped but none of the wiring or switches were touched or altered, then your problem is not with the switching. If someone has been adding or subtracting wiring (you mention redeocration) then the switching may be an issue.

Assuming nothing has been done to the wiring, what tripped? One of the circuit breakers or the RCD? I suspect, as we're talking lighting, it was a circuit breaker, which tripped because a light bulb blew. Have you checked the light bulbs? If the bulbs are OK and nothing's been done to the wiring, check the connections inside the ceiling rose or light fitting (power off first) as one of these might have been broken by the bulb blowing.

PJ

 

[ericmark]

There is a cheat method with twin and earth but I would strongly advise against it. The problem is unless the supply and return run together the cables can produce a mains hum in radios, TV's etc.

The standard method is to use triple and earth between both switches and the connections are like for like. The common does not connect to power or lamp so if for example switch is marked Com, L1, L2 then the L1 and L2 terminals do the switching.

The cheat is either L1, or L2 is always live so you can borrow live from the adjacent switch. However as well as the mains hum problem where two supplies are used for lighting (i.e. upstairs and downstairs) then a very dangerous borrowed neutral situation can accrue.

So I will not lie and say it can't be done as it can. But I would not recommend it.

The way out is wireless switches. There are a few on the market and so if renewing cables is not an option then rather than try with just two cores I would fit one of the wireless types. Some even have a TV type remote very handy to switch on light before you leave the car.

 

[ban-all-sheds]

Looking at the wiring, there is a 3core + earth from the 1st switch to the 2nd switch. Then only a twin + earth from the 2nd to the 3rd. This all worked a while back, but electrics tripped one day and never worked again.

I have done a continuity test on the 3core + earth and it is dead on one of the cores, but its not shorted to any of the other cores or earth.

Why don't you do us a drawing of which switch terminals are connected to what, including permanent lives from the loop and switched lives going to the lights?