Yellow liquid coming from electric shower switch!

How old is the installation and how old is the shower?

It could be two things as far as I'm aware,

Melting switch plate or melting cable insulation. The shower could be rated higher than the rating of the cable or switch, and it is not uncommon for wires to become loose(or not have been tightened enough in the first place) or wire strands to be cut to fit into a switch terminal. Both of these issues could cause melting of the switch or cable insulation, and producing a gooey substance.
This seems more likely as the heat from the switch would indicate this.

Or if it is an older installation:
It was common in old PVC earth sheathing for a plasticiser to be used which does produce a yellow/green goo over time as the copper reacts with it.
It is slightly toxic so it should wiped clear to ensure it does not get into eyes or mouths.(Particularly with little ones around!)
Although this seems unlikely as you said the switch gets hot.


I do think you should get an electrician in to check the installation if you do not feel comfortable looking behind the switch for issues. Remember you should not take the switch plate off before isolating and proving dead the circuit.

The sparks on here will have better ideas.

 

i agree do not touch get a spark in asap

 

Dont use, switch off at your fuse board/consumer unit and get a spark, it could catch fire.

 

Monkey spunk

 

Yikes, something is melting.

Turn off the power(breaker) to the shower and get a spark to lock it off so it can't be turned on until it is fixed.

Does the pull-cord switch still operate by any chance?

The isolation switch fails often as the terminals corrode badly and cause a bad connection with high resistance. This in turn creates allot of heat and melts the switch, housing, and terminals in some cases i have seen it welds the brass contacts together in a horrible mess.

If one opened up the pull cord switch you would most likely see it melted and the presence of copper sulphate(green blue) crystals formed on the terminals and cable.

The Monkey Spunk oozing out could well be the molten plastic which was white but is now tanned from the heat. This plastic is self extinguishing so unless there is other combustibles around the area it won't burst into flames but the risk is high so turn the breaker for the shower off and get it fixed. Regardless the point is that this could result in a far more expensive fix if you continue using it.

You can take a bit of tape and place it over the breaker switch and write on it "do not turn on" for now until you can fix it.