On 22/01/2019 20:08, Jim GM4DHJ ... wrote:
"Steve Walker" wrote in message
...
On 22/01/2019 10:41, alan_m wrote:
On 22/01/2019 08:55, Jim GM4DHJ ... wrote:
do you think the merrycan way of switching with down off is more
sensibubble
that what we do in the uk ?




Two way switching uses both conventions.

Up/down os probably only really seen with older tooggle knobs on
switches. Most of us probably use sockets/switches where pressing the
lower part is on and pressing the upper part is off.

I once worked on a rack of equipment where the (military) customer
specified that a big red illuminated front panel light meant the power to
the electronics was off! Guess how much damage was caused to plug in
boards that didn't like to be hot plugged?

I have worked on designs for many oil and gas/chemicals companies. Most
have wanted a green light for say a pump running ok and red for stopped or
failed, but some wanted the reverse, as they reasoned red for energised
and green for deenergised and therefore safer. A few even wanted a mix,
with green being for fail-closed valves that were in the open position and
for fail-open valves in the closed position, thus showing their
energisation rather than their positions.

SteveW

would they not have been better with black buttons on a black background
that light up black



"€˜Its the wild colour scheme that freaks me out, said Zaphod, whose
love affair with the ship had lasted almost three minutes into the
flight. 'Every time you try and operate these weird black controls that
are labeled in black on a black background, a little black light lights
up in black to let you know youve done it."

Zaphod Beeblebrox, The Restaurant At The End Of The Universe


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