Pinsulation Story
(why we have insulated pins)


Many people believe the reason we in the UK have insulation on the pins of our plugs is to prevent people from getting a shock when plugging in or unplugging.
While this may be partly true, a serious incident that was probably meant as a college prank went horribly wrong, this forced the hand of those in authority.
We have had uninsulated pins for many years, beginning with the 5 and 15 amp plugs, even the first 13 amp plugs were produced with uninsulated pins, but it was this story (told to me by a college lecturer) that changed all that.

Remember that our 13 amp plugs have a fuse fitted in the live conductor.

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A lecturer at a college set up an overhead projector and needed an extension lead, he plugged it in and heard the fuse in the plug pop, not knowing if it was the fuse in the projector plug or the extension, he plugged the projector directly into the wall to test it.

There was a bang and a flash, the lecturer was temporarily blinded, but his sight came back to normal after a while, they found that someone had jammed a small coin between the pins of the projector plug, so this was a direct short to a 30 amp circuit, i believe it was a piece of fuse wire in the main fuse, so the overcurrent would have been more like 45 amps.

A few days later the lecturer was driving to the college when his eyes started hurting, and his vision started going blurry, he had to pull over on the side of the road and get his wife to pick him up, she took him to hospital where they discovered detached retinas.







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