I didn't use a ball valve - electric solenoid valve from a washing
machine and water level sensor... When the mains pressure drops there
is a switch that prevents the valve from opening... Overkill but
Because the house has only one circuit, the incoming main also feeds
the taps etc., hence the quick emptying...
I guess that the UK has regs to prevent this type of installation but
here... well, who knows...
So if you have a power cut, how does the tank get filled up ? I also hope
you used a floating mercury contact as the water level sensor, because any
other type when faulty might not switch the valve off properly. The mercury
float has two pins inside a float ball that contains a small amount of
mercury metal and when the float is tilted up on an arm the mercury flows
against the pins and makes the circuit to switch things on. Very simple and
doesn't need any electronic circuitry to make it work, it only relies on the
electricity flowing through metal conductors.
| > I was listening to some music whilst replacing the condensers in
| > an old AC/DC valve radio (dropper resistor, no transformer) and
| > wondered why the music crackled every time I soldered something.
| > Then I realised that the music to which I was listening wasn't
| > from the hi-fi but the mains-powered radio on which I was currently
| > working.
| Nasty !!! :-)) But very easily done.
I didn't feel anything and the radio was unharmed too. They don't make them
like they used to.
The value of isolated bench power supplies (in that I didn't have one)
was brought home to me when I moved a metal desk lamp too close to the
live chassis of the TV set I was repairing at the time.
Luckily I only just caught one conductor, so no excitement - I would
imagine it would have still worked fine as long as you didn't stick you
finger in the hole.
I have drilled a cable before though buried deep in a wall, no evidence
that a cable should be ruining anyway near
Biggest electrical fright I had was when I was about 15, I was helping
out at my cousins house they were doing up. There was a very old and
defunct fuse box to be removed. They said it was all disconnected, I
didn't check of course. I forget exactly what happened, but the mains
supply was obviously still live as at one point there was a great big
BANG, FLASH etc. and I fell off the step ladder.
Moved into new house in Holland, trying to find out which fuse
controlled a particular lighting point (no fittings supplied), so put
neon screwdriver on bare wire. Only discovered when I managed to get the
feeling back in my arm that I'd used the 24V car tester instead of the
A Belgian colleague put his multimeter across 2 phases of the computer
room supply to measure the voltage, but left it on the mA setting. It
took him a couple of hours to stop shaking. I don't think the meter was
much use afterwards!
There's even a word for doing this on a big scale in the
States. When a digger unearths and breaks a mains
or digital cable its called 'backhoe fade'. Backhoe is
a digger bucket. I've always liked that.
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