A cold dark morning at Ealing Common depot. Me and my mate climb on board an 8 car 'Q' stabled on the alps to prep it for service. I do the doors and all the necessary at the east end and start to walk through to do the other end checking the condition of the cars, whether all the doors have opened, car lighting etcetera.
I get to the middle of the train and find it very dim as most of the car lights are out. Now on a 'Q' stock the car lights are incandecant lamps rated at 125v DC each in a series of 5 thus sharing 630v between them. If one in the series goes out or blows they all extinguish. There were 5 sets of five to a whole car. Well this car had 3 series out so it was therefore very dim and not fit for service.
So it was 4 on the whistle to get the fitter out. He toddles across bleary eyed and yawning. 'Wossamarrer mate' he drones. 'Got 3 series of lights out on this car cock' I reply. So he plods away to get a box of lamps and returns and climbs up.
With his torch he checks and tests bulbs and manages to get 2 series working again. He can't find which bulb in the 3rd series is the culprit so he take all the bulbs in the series out and looks into the sockets [all LT lamps were american Edison screw type ones BTW]. He replaces 4 bulbs of the series as the sockets seem to be OK. On the fifth socket he stops, shines the torch, says 'aha, thats the one' and promptly sticks his finger in the hole!
INSTANT AFRO HAIRCUT!! and all the rest of the bulbs lit up too. My mate took off his hat and grabbed his arm with it and yanked him free. [DC current will hold you and you CANNOT let go] The poor fitter collapses on the floor and his finger is black.
We sent him packing back to his hut to recover and put a bulb into the socket so that any curious passenger does not decide to do the same. It did not bring the series up but you were allowed to run with one series on a car out so it did not matter..
The moral of this story is,
NEVER PUT YOUR FINGER IN STRANGE HOLES!!