When I did my train driver training in 1991, we were being shown round the engine room of a big freight loco. The instructor packed a small group of us into the clean air compartment and told us what the various pieces of equipment were that we had seen, 'This is the the PGCOS: the Passenger/Goods Changeover Switch, this is the LMAG: Low Main Air Governor', and so on.
Then he pointed impressively to a grey cabinet with a prominent High Voltage warning sign on it: 'This is the DFT cabinet', he said, glaring at us. We all looked at it, suitably impressed, until someone found the courage to ask, 'What does DFT stand for?'
'Don't F*ckin' Touch!'
I've never forgotten that, and to this day I've never looked in that cabinet!
Regards,
John.