moved light switch, now it doesn't work...

[citoyen]

I thought it would be a very straightforward job but now the light isn't working, and I really don't have a clue what I've done wrong...

The consumer unit is inside the cupboard. A cable comes out of the consumer unit into a junction box. From the junction box, one cable runs to the ceiling light fitting, another cable runs to the switch, which is on the outside of the cupboard.

All I wanted to do was move the switch to the other side of the cupboard, so I disconnected the switch from the cable, unscrewed it from the wall, lifted the cable clips, re-routed the cable, then re-assembled it all in the new position.

But no light.

I made a diagram of the wiring before I disconnected anything, to make sure I put it back together the right way round, so I don't believe that is the problem.

Anyone got any bright ideas? (crap pun intended)

d.

[citoyen]

Oh yeah, and I've checked that the bulb hasn't blown so it's not that either.

[rogerzilla]

Did you pull on the wires?  Are they securely attached?  Electricians are sometimes really bad at tightening terminal screws, which should be tight enough to grip the conductor hard, but not so tight that they cut it or reduce its area.  If it's a two-way switch then it's possible to mess up the wiring order at the switch, but not for a simple one-way switch - the worst you can do is end up with it working upside down.

[nuttycyclist]

My get instinct is you're disturbed the connection at the other end of the wire.  As Rogerzilla said.


My silly question of the day - you have turned the mains back on, or the Circuit Breaker you turned off

[citoyen]

It's a simple one-way switch. Looking in the junction box, the wires all seem to be securely connected there.

Nutty, forgetting to switch the mains back on is just the kind of thing I would do... but I've checked and it's not that.

I'm utterly bewildered. 

d.

[nuttycyclist]

My other thought would be that the wire has snapped inside the casing.  But that's unlikely.

Have you got a mains detector?  (Mine is just a simple draper screwdriver with LED in the  handle.  When I put it near a live wire it glows red.)  If you have then you could at least see that there is mains in the wire.

[citoyen]

I don't have a mains detector but I did wonder if perhaps the cable was faulty, so I'm going to pop along to B&Q in a minute to get some replacement cable. I'll pick up a mains tester while I'm there - it would be a useful thing to have in the tool box.

The loose connection does sound the most likely answer, even though it all looks OK, so I'll also go over the wiring carefully again.

d.

[nuttycyclist]

That screwdriver I mentioned was cheap and is very handy.

It also has the advantage that it lights up when you're undoing a terminal that is live...

[Rapples]

It also has the advantage that it lights up when you're undoing a terminal that is live...

Why am I not surprised you know that

[clarion]

They are lifesavers.  No good for checking lower voltages, but you can track 240v with it.

[Jaded]

Even if electricians have tightened the terminal screws up properly they can work loose over time with the buzzing from the AC.

[citoyen]

OK, problem solved. And I can't believe what a bloody idiot I am.

The main power line into our house splits in two after the meter to feed two separate consumer units. There's an RCD on the line between the meter and the consumer unit that feeds the lighting circuit I was working on. I hadn't noticed that the RCD had tripped, so all the power was off in that side of the house, not just the lighting circuit...

 

To be fair to me, we do have stupidly complicated wiring arrangements in our house, and the RCD is in a different place to the consumer unit, so its existence had completely slipped my mind until we noticed that the power was off in that side of the house.

d.

[nuttycyclist]

OK, problem solved. And I can't believe what a bloody idiot I am.
...

Well I did ask the silly question


Glad it's sorted.