Help wiring double light switch

[Mike]

I have light on the hallway and another on the upstairs landing. They are controlled by two identical double switches, one upstais one downstairs. The upstairs switch seems fine, however the downstairs hallway double light switch looks like this..

's how it has been wired for 10 years until the lower red wire came loose recently and the upstairs landing light stopped working. I refitted it and now the light works again, however, the back-box and fixing screws now show as "live" with my test-screwdriver. I noticed this as I was refitting the screws and the driver showed as live.

As can be seen here

the two earth wires are not fixed to the back-box.

Can anyone tell if this is wired correctly from the photo's?

Thanks, Mike.

[Lurch]

On Fri, 10 Dec 2004 18:39:46 +0000, Mike strung together this:

It looks untidy and I wouldn't be happy if it were one of mine. There should be red sleeving on the blues and yellows and the earths should be connected to the back box.

[Coherers]

The muppets who wired my place failed to connect the earth for the entire upstairs circuit back to the earth bar on the CU with the result that the back-boxes and fixing screws would give you a light shock if touched. The capacitive coupling of the live wire on the earth conductor induced an AC voltage of 240v on all the interconnected backboxes etc. Shocking, but not very dangerous, as the jolts were never high current.

The reason I mention this, is that is *possible* that the "live" measurement you get with the test screwdriver is due to the same effect. However, unless you **know** that the voltage on the metalwork is not due to it being connected to directly to the live conductor it could be dangerous to just assume it is. (i.e and connect the earth). You really need to test the phase-metalwork impedance to ensure it is not a short.

As for the wiring, without seeing the way the pendants are wired, I wouldn't like to comment. But from what I can make out in the photos, I couldn't see a clear error. But I wouldn't be very confident as I am not sure which wires go where.

YMMV E&OE

[Lurch]

On Fri, 10 Dec 2004 18:39:46 +0000, Mike strung together this:

The other thing, neon screwdrivers aren't really any use for accurate testing, they show live when they feel like it and don't when they don't, not to be relied upon as an accurate indication, more of a rough guide as to the liveness of a particular thing.

[Dave Plowman (News)]

The normal way to wire a two-way switch circuit using triple and earth where the switch pair is at one switch is to wire Com to Com, L1 to L1 and L2 to L2 using the triple and earth, and then the switch pair across L1 & L2.

Thus:-

L1 L1 0===========0 0===========0============= Line | \ / | C 0================================O C \ / \ / 0===========0 0===========0============= Switch return L2 Optional L2 Intermediate