Problems with fitting a flourescent Light

[maderic]

Today I have tried to replace a single light bulb in my garage with a 5ft flouresent strip. There are two wall switches at either end of the garage that used to control this single light bulb. First thing I did today was disconnect and take down the ceiling rose which of course revealed two three core cables colured red, green/yellow and brown. Now I thought it would be an easy job to just connect these cables inside the new flourescent fitting. What I did (maybe foolishly because I couldnt see another way of getting the new fitting to switch from each wall switch) was to put the two lives, two neutrals and two earths into the relevant connector inside the flourescent fitting. What happened next was a bit of a bang and the one wall switch has gone. I can get the new flourescent to illuminate (from one of the three cores at least) but couldnt get it to switch off.

I hope this sequence of events makes sense and would really appreciate some help. I realise that I may need a sparky but was thinking somebody could point me in a simpler direction

I have photos but cant work out how to upload them

Thanks[/img]

 

[Spark123]

Sounds like you have made a common mistake, you say you have 2 cables (red+gn/y+black) entering the fitting? One of these cables is likely a switch wire. //wiki.diynot.com/electrics:lighting:problems:blackswlive

 

[RF Lighting]

Is it really red & brown or might it be red and black?



See here: //wiki.diynot.com/electrics:lighting:problems:blackswlive

 

[tim west]

This is the typical mistake made by DIY'ers when working with 2 way lighting circuits, as we are not allowed to repeat what has been said before( all blacks together, sounds like neutral and switchline connected together) i'd refer you to the sticky section where you will find the answer under two way switching.

 

[maderic]

Yep sorry my mistake, not brown but black

 

[maderic]

"Once you have identified which cable is switched live, put a piece of red sleeve over the black wire to signify it is a live. You now need to connect all reds together but to nothing else, the switched live black (with red sleeve) wire to the brown wire or L terminal for the lamp and the other one or two black wires with the blue or N terminal for the lamp.
Connect all earths together and to the earth terminal if required."

Im a bit confused now. How do I connect the two reds together but to nothing else and what do I connect it with?

So its one of the blacks (the true neutral wire) to the blue, earth to earth is easy, and the switched live to the brown live in the fitting????Is this right?

You will now need to disconnect and separate out the red and black wires to identify which one is a switched live.
If you already know which is the switch wire then you can jump this step. With your multimeter set to ohms range, connect across one of the red and black wires on one cable whilst operating the light switch on/off. If you see the resistance of the meter go from low to high to low etc when the switch is operated then this is the switched live. If not, try another cable.

Im a bit of a newcomer to multimeters and dont really understand this.Could you just make it a bit clearer for me

Thanks very much

 

[Spark123]

Im a bit confused now. How do I connect the two reds together but to nothing else and what do I connect it with?

Use a spare piece of terminal block to connect the two reds together, but just the two reds.

So its one of the blacks (the true neutral wire) to the blue, earth to earth is easy, and the switched live to the brown live in the fitting????Is this right?

Yes

You will now need to disconnect and separate out the red and black wires to identify which one is a switched live.
If you already know which is the switch wire then you can jump this step. With your multimeter set to ohms range, connect across one of the red and black wires on one cable whilst operating the light switch on/off. If you see the resistance of the meter go from low to high to low etc when the switch is operated then this is the switched live. If not, try another cable.

Turn off the power. Disconnect both the cables from the fitting so both red and black wires are spread out. Set your multimeter to ohms range. Connect it across the black and red from one cable. Ask someone else to operate the switch whilst you hold the test probes onto the wires. The resistance on the multimeter needs to go from high to low or vice versa when the switch is operated. If this doesn't happen, try across the red and black from the other cable. The cable which goes from high to low resistance when the switch is operated is the switch cable. Put a piece of red sleeve on the black wire on this one to identify it as a live as opposed to a neutral. Then connect up as above, both reds together, black to neutral, black with red sleeve to live, earths to the earth terminal.

 

[maderic]

many thanks for that simple explanation Spark. I''ll go get myself a multimeter tomorrow. First thing I'll need to do though is get another wall switch as I buggered the one today when it blew. I guess this'll be the first problem as the insides of that will no doubt be different. I'll let you know how i get on.

Cheers

 

[Spark123]

If it has a switch at either end you will need to buy a 2 way switch.
Another thing to do is to make sure you write down where each wire goes in the old switch, even if they are different it will help someone here to tell you how they go with the new switch if you struggle.

 

[maderic]

Yeah I took a picture of the knakkered switch and where the wires go so I'll know where L1, L2 etc goes. That should help!

By the way before I go tonight can you tell me what the yellow wires are coming down into the switch? They are in both switches

Cheers

 

[Spark123]

Yeah, they are most likely to be part of the "strapper" wires between the two switches. In one switch you will probably have a red, yellow, blue wire transposed to the other switch, in one switch there is likely a twin and earth (red+black wire) which goes from the switch to the light. This is the switch cable. If you look in the Wiki under 2 way lighting there are a few examples in there.

 

[maderic]

Amazing what you learn on these forums! Yes the insides of the switches are pretty much as you described. The switch that I believe carries the switch wire also has these two red wires connected together by plastic connector but attached to nothing else.

Would it not be easier and save me a few quid to get in space above garage and trace this switch cable back?

Thanks

 

[Spark123]

It is a lot easier with a multimeter, they come in handy for a whole rake of other thing too like checking fuses, checking batteries etc, you can pick them up for not much money at all.

 

[maderic]

Spark, too late now tonight and too dark but I did my multimeter. Ive also got my new two way switch. I notice though that the connections are different. On the old fitting we had L1 at the top of the fitting L2 and L3 with red going into L1 yellow into L2 and blue into L3

On the new one its COM on the top of fitting plus L1 and L2. Could you save me some time and tell me what goes where in the new switch

Thanks

 

[securespark]

Get some good testing practice in with your new meter.

Set it to continuity (beep).

Now place one probe in the Common terminal of the new switch,
and the other in the L1 terminal.

Switch the switch & note the beeps and their relevant positions. Do the same between Com & L2.

Now, apply your probes to the terminals of the new switch & see if you can work out which terminals on the new switch relate to those on the old one.