Archives for posts with tag: grumpy

Getting electrocuted

Have you ever experienced an electric shock? I have. many times. I guess being the son of an electrical engineer fed my interest in powered toys and my education led to the same type of career but my first shocking memory is of being put to bed in a spare room while my parents were visiting friends. I was probably four or so and I was mesmerised by the empty socket for the reading lamp above the bed. Naturally I stuck my finger in it and received 240 volts across the tip as I shorted the bayonet mount contacts. This was a shock in all meanings of the word and resulted in a burn.

We’ve all put our tongue across the terminals of a 9V radio battery haven’t we? I made a lot of electronic toys with triacs that bit and capacitors that discharged through me. Then I was employed repairing adding machines and computers with all kinds of high voltages or large currents. I once watched as a colleague used a spanner to loosen a bus bar from a large capacitor bank in a system which had been turned off and disconnected but not discharged. As he shorted between two bars the spanner disappeared literally in a flash right in his hand. Amazing.

Another time I was present when a switchboard I had assisted to wire up was tested with very high currents. It had 3 phase power running through copper bus bars 6mm thick and 10cm wide but we had forgotten to install the plastic insulators between them. As current flowed the electric fields caused the bars to bend and touch. There was another flash and when we opened the cabinet there were no bus bars to be seen but the entire inside surface of the cabinet was copper plated. Impressive.

A shock between one hand on a 240 volt connector and the other hand on a good earth is like being kicked in the chest by a mule. Trust me. A shock through your arm or fingers will cause the muscles to involuntarily contract very quickly. I was once standing in a factory next to a guy who did just this while holding a screwdriver. He unintentionally flung that tool straight up with such force that it was embedded in the roof some 10 metres above.

My favourite occurred while I was adjusting the picture on a video monitor from behind while the young lady at the keyboard provided feedback on height, width, pincushion etc. I touched the high voltage going to the crt which was about 12,000 volts but with no real dangerous current capability. I grunted and pulled my arm out instantly but the real shock came when the girl screamed and leapt to her feet. I don’t know what I thought but I screamed with her and the whole room full of operators screamed with us. Then we all had a great laugh.

Most modern electronics is low voltage and safe but I am sure there is still time for me to stick a finger somewhere I shouldn’t in a washing machine or something. With a name like Sparkes it is almost inevitable.

cheers
Spike

Advertisements

Which way is up?

Yesterday we were having breakfast in Marcoola when Carol said how nice it is to ‘come down the coast’ and then quickly corrected herself to ‘up the coast’. She was referring, of course, to the fact that we were north of home. From Brisbane, ‘down the coast’ means the Gold Coast, that seething den of drugs, vandals, violence and tourists whereas ‘up the coast means the Sunshine Coast, the bright, friendly strip of sun-washed beach towns. ( I hope my geographic bias is not showing.) However, since Brissie is 10km inland and up-river it is actually downhill in either direction. As John Masefield said:

I must go down to the seas again, to the lonely sea and the sky,
And all I ask is a tall ship and a star to steer her by,

There is no mention of north or south here. Who decided that north is up and that all maps should be drawn that way? Was there a worldwide convention at some time that reached such an agreement? I have read that the Chinese may at one time have felt otherwise and that the word ‘north’ is derived from the German ‘nor’ and the earlier ‘ner’ which actually means ‘down’.

If someone had decided to paint the south pointing half of a compass needle red instead would everything be different? On further rumination I have decided that since the majority of early astronomers lived in the Northern Hemisphere they probably noticed that the stars seem to revolve around a point in the sky which probably seemed like a good start to navigation.

Here in the south in Australia, previously Terra Australis which means Land of the South, we have had an indigenous population for 30,000 years. Much of their art consists of abstract representations of their homeland in the form of maps or aerial views. I wonder whether they are oriented with north upwards. Does anybody know?

In the meantime, as Canned Heat once sang, I’m “Going up the country.”

Cheers
Spike