Kevin,
Of
course I
did not mean to work on a live circuit, but then I had assumed that anyone
with
an ounce of sense would know that so anyone in this group should be just
fine
in that department. You should never work on a circuit that is not dead
what I meant
was that if the wiring was wrong in any way an RCB protected circuit is far
better for working on for people that are unsure as it just pops the
breaker if
there’s a problem and RCB’s have been a legal requirement for
habitation
certificates since the eighties. Also they are mostly retrofitted on any
major
electrical work carried out in the past 10-15 years so they should cover a
great many people. I did also point out that a meter, obviously capable of
reading mains voltages, was really needed simply as this is a far more
accurate
and positive way of checking for juice than a simple mains tester, which
only
tells you if there is a live feed, nothing much else unless its an LCD one
that
can give an indication of earth leakage if used
correctly.
What
my
intention was was to point out the simplicity of the task at hand and if
I’m
still not 100% sure I ask a spark to have a look and either do the job or
advise on the best way forward.
K.
-----Original
Message-----
From: Kevin Hawkins
[mailto:tivo@xxxxxxx]
Sent: 23 April 2001 01:20
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Urgent
question on AW10's
I must really say
that I
am gob smacked here - Mains IS a problem and it is lethal. Treat it with
the
utmost respect. There is an inference from this post you can experiment
with
live mains if you have an RCB all will be well - and that if you dont
you'll
just blow a fuse. This is NOT true and I don't think Kenneth meant it to
sound
that way. It's just ambiguous.
Whilst most 'sparkies' flaunt the risks they also do so in an
educated
way. Whilst it is probable that you are unlikey to come to harm with RCB's
in
circuit the biggest risk is not knowing if they are protecting you,
particularly if you are not knowledgeable.
I would strongly recommend - let me rephrase that -
ABSOLUTELY INSIST - that you NEVER NEVER work on a live mains circuit -
always
ensure that the fuse is removed (or tripped) for that circuit before you do
anything. ( also make sure also that no other person will reset the fuse if
it
is a trip type eg for a lighting circuit shared with other people).
Use a
mains neon tester on the live wire to prove the circuit is dead, Make sure
you
are reasonably well earthed when you do this (it makes the neon indicator
brighter and more definative) - and only ever physically touch the top end
of
the screwdriver.
Having said that what you are trying to achieve here is
fairly straight forward and lots of people here can give you advice. The
timers
are likely to be fed by one common llive supply (brown or red wire) that is
split into 3 switched live supplies after the timer switches (still red or
brown wires) it is each of these 3 that you need to intercept and either
connect in series with through a relay (Timer ON permanent) or in parallel
with
from the main supply to the switched (Timer OFF permanently).
I you have a fax I will send you a sketch of what to do
if
that would help but please never get complacent about the mains - and never
work on it live even if there is an RCB on the supply. If in doubt get an
electrician in.
I am sorry if I am ranting and raving to people who know
all these
things but I have a past experience in this area that I would never wish to
see
happen again.
Kevin
on 23/4/01 12:43 am, Kenneth Watt at kennethwatt@xxxxxxx
wrote:
Mains is not a problem, you just need to follow some basic rules and
have a
meter to hand :o) anyway, a little jolt is good for the heart now and
then,
at least that's what my boss used to tell me! Don't worry
about
experimenting, particularly if you have an RCD unit, you really can't
do
any
harm if you have one of those. Fused supplies are a bit more tricky if
you
do the wrong thing, but still as long as your not holding an open live
&
neutral the worst you can do is pop a fuse.
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