Not sure if there are any UK electricians on here, or how similar the electrical industry is to the American system, but here it goes...
I recently moved into a flat in London. A combination of being inquisitive and being too broke to pay for an electrician has prompted me to try and install a new plug socket (outlet?) within a wall in a cupboard. The person inducting me into the new flat pointed to a plate with no interface (just a flat plastic panel with screws) and said "if you want to add a socket in this utility cupboard, that would be the place to do it".
Here is a quick illustration I did of what he was pointing at:
The plate without an interface was the one he pointed at, but the ventilator switch becomes part of the story.
So I went about unscrewing the plate and taking a look at what is underneath it. I thought it might be a simple case of buying a socket to replace the blank plate, and fixing some obvious wires to it.
What I saw when I opened the plate was a load of grey cables connected to a connecting strip on one end, and a flex cable connected to the other end. Some of those grey cables are coming from above, and some (on removing the ventilator plate) I can see are going into the ventilator switch.
The white flex cable travels north up the wall - and I presume it is the ventilator - but it has a fourth flex core (black) going into the connecting strip. On close inspection of the setup, it all got a bit confusing.
I have drawn a very accurate illustration of the setup (note all the wires are going exactly where they are going in real life). I decided to illustrate it (rather than take a picture) because a photograph cannot describe the complex setup. Note that blue is neutral, brown is live and yellow is earth. I have no idea what the black cable on the 5-core flex is; or what it is doing.
Can anyone make sense of this setup? Where would be the best place to put a plug socket (outlet) and would I need to reconfigure anything to do so?
Any help would be super appreciated. Thanks in advance.