Light switch questions - green goo / twisted wires

[db_york]

I want to replace a light switch with a dimmer (for dimmable LED lights)

When I opened up the switch (photo A) I found two puzzling things

1. Sticky green residue on bottom of the box, also on a terminal block. I wiped it off onto tissue (photo B)

2. Two red wires twisted together and inserted into one switch terminal (photo A)




I checked a couple of switches nearby, another one has green goo also (photo C) - again, there's goo on a terminal block and I'm wondering if it's something to do with the copper wire in the terminal block giving rise to copper compound salts (green), which have absorbed moisture and generated goo.

1. What's the goo? Is it a problem?

2. What's the deal with the twisted wires? Old two-way switch circuit or something? Can I just replicate that wiring with the dimmer switch i.e. put the twisted wires into one terminal of the dimmer?

Thanks

 

[Shaggy]

I want to replace a light switch with a dimmer (for dimmable LED lights)

When I opened up the switch (photo A) I found two puzzling things

1. Sticky green residue on bottom of the box, also on a terminal block. I wiped it off onto tissue (photo B)

2. Two red wires twisted together and inserted into one switch terminal (photo A)


View attachment 6311View attachment 6312View attachment 6313

I checked a couple of switches nearby, another one has green goo also (photo C) - again, there's goo on a terminal block and I'm wondering if it's something to do with the copper wire in the terminal block giving rise to copper compound salts (green), which have absorbed moisture and generated goo.

1. What's the goo? Is it a problem?

2. What's the deal with the twisted wires? Old two-way switch circuit or something? Can I just replicate that wiring with the dimmer switch i.e. put the twisted wires into one terminal of the dimmer?

Thanks

That green goo is usually just oxidation from the copper, its pretty common over time, especially in older boxes or damp spots. Just clean it up and make sure the wires aren’t damaged underneath. As for the two red wires twisted together, yeah, that’s likely part of a 2-way setup. You can usually keep that same wiring when swapping in a dimmer, just double-check the dimmer supports 2-way circuits. What kind of switch are you putting in?