Am 20.03.2019 um 16:09 schrieb :
As part of re-wiring the workshop I want to be able to pull down a
socket (on a flex) from the ceiling when required and then to have it
retract when not needed. The action would be something like a roller
blind: pull and let go to latch down, pull again to unlatch and retract.
The roller blind mechanisms are quite long and fit in a tube whereas I
need something that winds a string.
What do I need?

Such a cable-retracting mechanism can be found in some floor vacuum
cleaners.