light switch replacement - keeps tripping electric

wakkaday

replacing light switch, keeps tripping. i put wires as they were in previous switch

its a two way light switch, on top of the hallway and at the bottom of the hallway there is another switch/light fixture and it is linked to that.

i put the wires exactly as in picture on the new swittch, but it keeps tripping

any tips/suggestions?

Section62

https://forums.moneysavingexpert.com/discussion/6661960/light-switch-replacement-keeps-tripping-electric

Are the switches identical? What exactly "keeps tripping"?

I'd guess the connections are different/incorrect, and you've set up a short circuit.

grumpy_codger

https://forums.moneysavingexpert.com/discussion/comment/81943699#Comment_81943699

I'd guess the connections are different/incorrect, and you've set up a short circuit.

I can't imagine how a switch with only 'line' and 'switched line' wires can be wired incorrectly to cause short circuit (unless the wiring or the light fitting is faulty). The only short circuit can be with 'earth', and BTW the switch isn't earthed although it has to be.

That said, the photo isn't very clear, e.g. I don't understand why 5 wires (2+2+1) are connected to one of the switches.

Section62

https://forums.moneysavingexpert.com/discussion/comment/81943740#Comment_81943740

Two of the cables are Blue/Yellow/Red - which means the wiring probably dates from a period where switched neutrals were a thing.

I'm not saying there is a short circuit for sure, but if 'something' is tripping when the switch is operated then it would suggest there is either a neutral or 'earth' in the mix, along with the expected live / switched-live. Another possibility for a 'short' is if the switches are on different lighting circuits with separate RCBOs or RCDs - inadvertently connecting two different circuits via a switch can have interesting results.

Edit:

That said, the photo isn't very clear, e.g. I don't understand why 5 wires (2+2+1) are connected to one of the switches.

2+2+1 is one of the standard ways of wiring a 2-way switch. But not in the combination pictured.

grumpy_codger

https://forums.moneysavingexpert.com/discussion/comment/81943756#Comment_81943756

Two of the cables are Blue/Yellow/Red

all(?) with red sleeves

2+2+1 is one of the standard ways of wiring a 2-way switch.

Any link? The only way I know is 1+1+1 (like the back switch in the photo). Yes, I see, the light (switched line) and the 'line' are connected directly to one switch that makes 5 in total. However, in this case 2 and 2 have to be connected to L1 and L2, not to COM. Correct?

Yes, different RCDs is a possibility, although unlikely.

And yes, it's important what exactly is tripped - RCD or MCB.

bjorn_toby_wilde

I don’t think the OP has wired them as they were in the original. The yellow sleeved with red by convention is a switched live but it’s in the COM terminal nearest to the camera. The plain red is normally the Common live and that’s in L1.

Is the cause of the confusion the fact that the two gangs are oriented differently? The COM terminal is at the top on one gang and at the bottom in the other gang. If trying to replicate from a picture and the original switch had both COMs at the top this might confuse things.

OP Do you have a photo of the original switch showing how that was wired? If you do, look closely at the labels on the terminals and check which wires are connected to COM, L1 and L2 and that you’ve replicated that correctly.

wakkaday

New switch actually different layout

L1 and L2 will be l11 and l22?

wakkaday

The original picture is how it was wired before I removed it to replace the switch.

The new switch has it differently no longer L1 or L2 but l11 and L12 etc

I replicated this on the new switch and it when the it would not switch on the mainboard

grumpy_codger

The original picture is how it was wired before I removed it to replace the switch.

Shouldn't you have said this in the very first post?

New switch actually different layout . L1 and L2 will be l11 and l22?

L1 = L11 (L21)

L2 = L12 (L22)

And is it that hard to answer the question - what actually is tripped?

Section62

https://forums.moneysavingexpert.com/discussion/comment/81943781#Comment_81943781

Yes, different RCDs is a possibility, although unlikely.

Not that uncommon.

Downstairs lights on one circuit, upstairs on another. On a split-load board upstairs lights on one RCD, downstairs on the other RCD (so one RCD tripping doesn't take out all the lights).

Double switch at the top of the landing has two-way circuit with downstairs switch on downstairs circuit, second switch is one or two-way on upstairs circuit.

Two circuits - potentially across two RCDs or RCBOs - on the same switchplate…. Needs great care to keep the circuits separate. And beware of the borrowed neutral issue.

In terms of the OP's situation, worth noting the two switches are wired differently. One side only has 3 wires.

bjorn_toby_wilde

https://forums.moneysavingexpert.com/discussion/comment/81943875#Comment_81943875

I can’t help thinking it’s the gang that’s nearest to the camera that’s the problem. Normally it would be 2+2+1 as you say but the 1 would be the COM terminal (the permanent live). In the picture it’s L1 that seems to have the permanent live.

Trouble is, if that’s the original wiring and it was working like that then why isn’t it now?

Is it possible the two reds (permanent live from the other switch and the live to the light fitting) have been swapped by mistake?