Replacing a 2 gang dimmer with 3 core cables?

[boznia]

I am trying to replace a 2 gang dimmer switch ( each 1 way ) with a normal 2 gang switch. Having unscrewed the dimmer i found 3 grey cables ( core? ) with red,black and earth wires in each. I only expected to see 2.

Presumably one of the grey cables is different from the other 2 ( which are for the lights ).

How should i connect them up?

Hope someone will help,

Ben

 

[breezer]

note what is there (Including marking cables) then swap each cable to new switch

 

[boznia]

All the blacks were twisted together into a choc box ( dead end ). The reds went into the back of the dimmer. Sadly, I can't remember where.

I ( stupidly ) assumed that one of the greys was for a old ceiling light which is no longer there, now I think it is the feed? if so how do i identify the feed?
and how should i wire it.

Thanks for your help,

Ben

 

[breezer]

trial and erorr usually results in a large blue flash and a bang. i Suggest you get a multi meter and find out, after all if you are doing any electrial work you should have one, you wouldn't put nails is with a screwdriver would you

 

[boznia]

Once I have discovered the feed, how do i wire it?

Thanks,

Ben

 

[Adam_151]

i'm afaid we need a little more infomation, can you describe how it is currently wired, or post a diagram or photo (or email it to me, and i'll post it, email is in my profile), anything we tell you without knowing more is going to be based on assumptions and therefore could be wrong

EDIT: theres been more posts since I wrote this,

red from feed to com on both switches, need to use jumper wire
red from others to L1 on each switch, there is one L1 per switch, one red in each

 

[boznia]

The only thing I can say is that all the blacks were twisted together in a dead end and the reds were the only wires connected to the back of the dimmer. One of the reds was stripped further down the wire in order for that red to go into 2 holes.

The switch is in my extension with two wall lights. I assume one of the wires is the live feed and the other two are the cables which take the power to each of the two lights.

Hope you can help, its getting dark soon.

Ben
+++++++++++++++++++++++

What I do not understand is why the 3 black cables were all wired together in a dead end.

My GCSE science suggests that the red black wires in each cable are effecively positive and negative and therefore need to be connected to either end of a switch.

Please help somebody.

Ben

________________________
moderator

please note 10a which is here

+++++++++++++++++++++++++++

I have almost solved the problem.

I put the 3 blacks back together in a bit of choc box, next I wired the red cable i believe to be the feed into the common of the first switch and one of the other reds into L1. Then I took a separate piece of red wire and ran this from the common of switch 1 to the common of switch 2 and the final red wire to the L1 of switch 2.

The lights work ok, but switch 2 is the wrong way around. I swapped the connections in switch 2 and it is still the wrong way around. Can anyone solve this much smaller problem?

At least I will be able to see tonight,

Ben

________________________
moderator

please note 10a which is here this is your 2nd warning in the same topic

 

[Adam_151]

On the second switch move the red wire that is in L1, to L2 instead

 

[kendor]

Probable that the red wire that is "stripped to go into two holes" is the live and this goes to both commons of each switch, the other two reds are the switchlines to their respective lights you will have to trial and error those to get the right lamp to switch on with the correct switch. use L2 on each switch for the switchlines one in each terminal.

 

[sparkybird]

The reason that your neutrals (blacks) are connected together is because you have a feed through switch - you need to make sure they stay this way or your lights won't work
SB

 

[ban-all-sheds]

My GCSE science suggests that the red black wires in each cable are effecively positive and negative and therefore need to be connected to either end of a switch.

Did your GCSE science not teach you that a switch makes and breaks a connection between the wires at either end?

And that connecting positive to negative is a Bad Thing™?

Or that our domestic electricity supply is AC, and therefore the conductors are not "positive and negative"?

 

[Adam_151]

And that connecting positive to negative is a Bad Thing™?

Not always...arc welding for example... though I doubt the OP wants to weld the contacts in his switch together

 

[pdcelec]

My GCSE science suggests that the red black wires in each cable are effecively positive and negative and therefore need to be connected to either end of a switch.

Did you pass or fail this subject?. If you passed then I would seriously question our education system.

 

[kendor]

My GCSE science suggests that the red black wires in each cable are effecively positive and negative and therefore need to be connected to either end of a switch.

Did you pass or fail this subject?. If you passed then I would seriously question our education system.

Perhaps it was a long time ago when the system was DC?