Electrics idiot needs some help with a simple dimmer switch

[dudley_rob]

I am calling out to the DIY electrics community to help. I spent hours messing about with the dimmer with no luck and short of calling out a london priced spark, I am lost. Please read down, I think its a very easy problem if you no fool like me!! Help!

I don't know much about anything so bear with me. The original 2 switch socket seems to only have commanded the 2 living room lights and no otherwhile it was wired up. My plan was to wire the double dimmer multigang in the same way.

My mistake was loosing track of which wires were which from the old socket. This messed everything up. No I don't know whihc wires cam out of L1 or L2 or C. I am pretty sure the circuit is one way in that 1 switch operates 1 light.

but...

When I was wiring up the dimmer and adding the little piece of wire from L1 to L1 to mimic the wiring in the old switch (or at least what I though it was) and then turning on the power the living room light was operating the bathroom and bedroom!!

This had led me to think that the wiring is now 2 way as depending on the way it is connected it seems to operate other lights or not alllow them to work at all.

Some of the combinations I tried seemed to not allow any lights to work. Some of them allowed one light to work and the other on constantly. It has an overload breaker in the switch so I don''t think it will go bang.

My problems are these:
1. Is this a 2 way or 1 way circuit
2. Am I wiring the cables into L1 & L2 or L1 & C
3. Do I need the little piece of wire from one switch to the other
4. Is the dimmer itself likely to be giving me problems

Please help me out, I am in massive need of some help here and which I'd never bought the bloody thing.

Yours with a nearly extinguished flame of hope
Rob

 

[dudley_rob]

additional to "dimmer switch" problem below mine.

It does the same thing as that guys but I would be happy with the 2 lights working from 1 dimmer switch.

I have 4 red wires so how can I make sure both lights work with one switch?

Cheers

 

[brown-nought]

Ok I thing its safe to assume you aren't that familiar with electrics and what started out as a simple job has quickly gone over your head.

Can I first clarify what you had before.
In your lounge you have two lights, each one was controlled from a single switch in on a two gang face plate. When you opened it up you had four red wires and earths?

My instinct is that you have a supply cable coming in, a supply cable going out. The remaining two red wires each go to one of the lights. From your description you had:-

Supply in to L1 (Sw1) a strapper (short wire) from there to L1 (Sw2) and then the supply loop out from L1. One red wire went from C (Sw1) and the other from C (Sw2).

In order to wire back up the dimmer you will need to identify the cables again. For this you will need a test multi meter.

When you re-wire I would move the arrangement to be

Supply loop in to Sw1 C, strapper to Sw2C and loop out. L1 Sw1 to light 1 and L1 Sw2 to Light 2.

Also if the dimmer is metal it will need an earth.

 

[dudley_rob]

brown-nought,
Thanks for you're reply. Greatly appreciated and yes I am not familiar with this stuff. It would have been fine had I labeled the wires upon disconnecting.

on your comments:
"Can I first clarify what you had before.
In your lounge you have two lights, each one was controlled from a single switch in on a two gang face plate. When you opened it up you had four red wires and earths? "
my reply: yes. but the earths (yellow & green) are connected to the metal box inside the wall. All I have to play with are the 4 red wires.

"My instinct is that you have a supply cable coming in, a supply cable going out. The remaining two red wires each go to one of the lights. From your description you had:-
Supply in to L1 (Sw1) a strapper (short wire) from there to L1 (Sw2) and then the supply loop out from L1. One red wire went from C (Sw1) and the other from C (Sw2). "
My reply: yes I think so. If I remember one red went to L1 and one to L2 and the same on the other side with a small blue wire connecting them from L1 to L1 I think.

Can you confirm that the strapper is the little piece of wire (blue in my case) from switch 1 to switch 2 and if it should go from L1, L2 or C?

When I use the mutlitest metre what will I be looking for on each red wire. Am I expecting higher readings on certain wires? the switch is only plastic.

I'll take note of your instructions and get me a multitest metre tonight. And go to work again tonight!

 

[brown-nought]

The earthing sounds correct.

In your case the strapper wire is blue. (Strictly speaking it should be red or marked with red tape - but that to one side for now].

It doesn't really make sense for you to have a cable into L1 and out of L2.

A two way switch has 3 connections L1, L2 and C (Common). Based one the position of the switch Common is either connected to L1 or L2 but never both. L1 and L2 have no electrical connection.

A question I never asked before was about the cables. You say you have 4 red wires, are these cables sheathed in grey or white plastic? You have 2 earth wires. You may have 2 Twin & Earth cables coming in with two red cores in each.

You will need to check the ceiling roses for the lights. See what cables are entering and leaving the roses and how they are connected.

I suspect you will have a loop into one rose with the supply. This will run down to the switch. The second rose will have the supply out with a twin red cable supplying it from the switch.

If this is the case you will need to identify in each cable which is the switch line and which is the supply line.

This is where the multimeter comes in. Obviously with the supply isolated!! We need to find which cable is the supply and which is the return to the light from the switch.

In the switch join one of the red wires to the earth

The using the meter go to each rose and test to see if either of the red wires coming in has connectivity to earth (using the continuity setting on the meter). When you get a match you will have both ends of the cable – label it !! Repeat this for the other 3 wires each time with one connected to earth. We are using the earth to give the meter a circuit between its probes.

Now the red wires in the roses connected to the brown rose wire are the switch lines. The other two red wires should be the loop in and out – we will call them supply.

Now connect one of the supplies you Sw1 C and the other to Sw2 C and put a red strapper wire between them (not blue or brown flex cable but a piece of 1.5 mm red wire.

Next connect the switch wires into L1 of the two switches (one to each - in the same order as the other cable in the sheath).

Finally check the earths are still connected and close everything up (remove the labels if made of paper) and test.

What ever you do not test on a live circuit its too dangerous. If your arrangement sounds different come back to us with more details. If however you cannot follow this advice it may be time to call in a sparky to fix it.

 

[dudley_rob]

Thanks for your help. I just don't have the know-how for this and frankly I'm lost on your explaination and I don't fancy a trip to casualty. Anyone fancy a trip to West London!
Cheers, for your help
But alll the wires are only red with no grey or white on them. Only white on them!! Useful eh?!

 

[securespark]

How many conductors in total?

 

[dudley_rob]

Thanks Brown nought,
I followed your instructions and saved myself a trip to casualty and the cost of a london sparky.
I also had the help on the phone from a cousin in law who is a qualified sparky.
Basically I identified the wire leaving the ceiling rose as one of the wires in the plug. Connected it up and then did the same for the other rose, wired a strapper in and the supply wires and hey presto, it all works!
Thanks for your help