When I've wired runs of 240v single phase 13A sockets in various buildings
on the farm I've always put them all on one phase so that there is no danger
of 415v phase to phase accidents when using things on leads - am I being
I'm currently wiring up a Tractor Shed with runs of 13A sockets on opposite
walls 40 foot apart. It would be convenient to put them on different phases
not only to balance the load but also to free up a 'way' in the breaker box.
But this goes against my natural instinct.
..... what does the team think ?
Well I can well remember many many years ago the factory I was working in
got a visit from the Electricity mob, as our new extension running soak
tests on colour tvs and with lots of Fluorescent lights was making a hole in
one phase. After much measuring and head scratching they did put different
parts of our factory on different phases at the Leccy folks expense.
I certainly do not recall anyone even mentioning the 440 volt issue,
though now you mention it I guess if you were really determined you could
This newsgroup posting comes to you directly from...
My factories all had 13A sockets on different phases, as did the
headquarters of the Electricity Board I use to work for. The basic rule
was to ensure that there was at least 6ft 6in (2m) separation between
sockets on different phases. To avoid any doubt, the sockets were marked
with red, yellow or blue phase discs, as appropriate, on the wall beside
them. I suppose these days, they would be marked brown, black or grey.
An electrician who is colour blind will presumably know it and use other
methods for identification, for the rest following a colour in and out
of junction boxes, isolators, etc. is the normal way.
yes but I had in mind not cable but the "illuminated indicators"
In passing I'm not sure how many colour-blind electricians are trained
these days. The JIB used to require a medical certificate to show
"absence of colour blindness in order to carry out the role to the
degree necessary to ensure no impediment to safe working and in
accordance with disability discrimination law" which left me not much
wiser. Employers are under a duty to assess the risks of any employee
who works with colour coded stuff. I don't know about insurance for
reply-to address is (intended to be) valid
Ah, fair enough. But each indicator should be labelled anyway. Coloured
indicators for each phase will still appear lit or not to a colour blind
person, so noworse for them than them all being white.
Incidentally though, it is normal on many control panels for green and
red lights to be used for running and stopped. Many people are red/green
colour blind, so they have to look harder at labels.
On screen control systems often have devices or valves that are green
for running or open and red for stopped or closed. I wonder how many
operators are tested for colour blindness?
From the quick look that I've done. Good colour vision still seems to
be required for apprentices, but not for people who work as electricians
and may have gained qualifications and experience without being an
She shouldn't have been doing. She should have been requiring other ways
that a colour blind person could get the information (such as
labelling), but not removing the best and quickest way for non-colour
blind operators to get that same information. A red/green indication can
be spotted from across the room, labelling and the like can't.
Not a few people -- around 1 in 12 men are red-green colour blind. I'm
not too severely affected, but I have great difficulty telling whether
an LED indicator is red, orange, yellow or green; though I can usually
see the change if I'm watching it. Flashing in a particular pattern
Wiring serial comms 'D' connectors was always a bit of a challenge, too.
Before I went to university, I worked for a year off in a research chemistry
lab where they did a lot of colour chemistry. My boss was telling me about
my predecessor who kept getting results that no-one else could replicate. To
begin with, the lad was just asked to repeat his experiments and still he
was adamant about the colour changes that he saw. My boss decided to watch,
to see if the lad was doing something different. Just as they were about to
get to the colour-change part of the experiment, the lad said casually "I
*am* colour blind - does that matter?". Yes indeed it did matter: what the
student was recording as a yellow to green change was actually the expected
red to blue change.
As my boss was telling me this story, I thought he was going to say that the
lad didn't know he was colour blind and this was how he first discovered it,
but no - he already knew full well but didn't realise that it would be
critical when doing colour chemistry.
On Sunday, 12 November 2017 22:20:41 UTC, Steve Walker wrote:
Not necessarily. I recently came across somebody who could not see red
at all. It was a sunny day and a glass ornament was casting a clear
spectrum on the wall. He pointed to the parts of the spectrum that he
could see. Red was simply not visible at all.
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