in this presentation we're going to do
the safe isolation procedure so we can
isolate the consumer unit and in this
case we're simulating a domestic
dwelling in order that we can work
inside that consumer unit perhaps to add
an extra circuit or carry out some of
the tests safely without the supply
being present within the consumer unit
itself we're fortunate in this case we
have a linked main switch in the double
insulated meter tails remote from the
consuming itself so we're going to
perform isolation here so we're going to
turn off that double pole switch and
prove the consumer unit itself is
isolated and therefore safe to work on
it
once we have turned off the linked main
switch in the tails we will need to put
on a locking device and a sign so people
are aware that the supply has been
isolated let's see how we're going to do
that
so stated in previous presentations i
never like to turn off switches on full
load however to give me some sort of
indication that the isolating switch has
turned off the installation i might want
to leave one or two circuits or maybe i
want to leave a lighting circuit on or
in this case i've plugged the voltage
indicator into one of the socket outlets
therefore when i do operate the linked
main switch i have some visual clues
that the supply has actually gone off
before taking the consume unit cover off
and actually proving it's dead so in the
installation we're going to first of all
limit the amount of current that the
switch remote from the consumer unit
will turn off and i'm going to turn off
circuit breaker
circuit breaker and circuit breaker
leaving on one of the circuit breakers
here that supplies the socket outlets we
can see my plug-in voltage indicator is
still illuminated but we're not going to
be turning off the whole of that
installation on full load and we have a
visual clue when we return to the
installation the supply has gone off
before the cover goes off equally you
could leave a lighting circuit on as
well
so i'll go to my linked main switch
remote from the consumer itself and i'm
going to turn that off this could be
located away from the distribution board
and therefore you mustn't leave it at
any stage turned off and re-enter the
building to see if for instance the
voltage indicator has gone off or lights
that you've left on regardless whether
you turn off the right switch and it
could be that there's several of these
link main switch feeding several flats
in the building you will still need to
secure isolation with a device and a
lock and a sign before leaving it to see
if the installation has gone dead as is
adjacent to the consumer unit we will be
able to see if the plug-in voltage
indirector has gone off when we turn it
off but the process is still the same in
the real world you must lock it off and
put a sign on it before leaving it so we
go to the linked main switch in the
tails now and we
turn it off
if this is remote from the consumers
unit we won't know what's happened to
the plug-in voltage indicator down here
but we have got to secure the isolation
at this stage so we'll do that next so i
need to secure the isolation i take the
device i position it onto my linked main
switch or double pole switch i'm going
to tighten down the clamp on this style
they're all slightly different
and then we're going to tighten that
onto the actual linked main switch
itself
might need to take a pair of pliers just
to make sure we nip that nice and tight
okay and that device now will not come
off
we position the locking device over and
you can see already you cannot turn back
on that switch but it still needs to be
secured with a padlock
padlock is accompanied by a sign
suggesting what we're doing
like so but i prefer the master lock so
we can do it that way
equally we can insert a master lock the
beauty of this is if there are several
trades on site
plasterers plumbers painting decorators
that would be affected by reenergization
of supply everybody has a chance to
insert their own padlock so the
electricians put his padlock on plumbers
painters carpenters etc can also add
their padlocks on therefore the supply
will not be able to be returned until
everybody's agreed it's safe to do so
and remove their padlock so we've locked
it off at the link main switch remote
from the consumers unit we now need to
go into the consumers unit in order to
prove that it has been isolated
so i've left the linked mains switch
isolated and secured i've taken the keys
with me and i've come to the consumer
unit before removing the consume unit
cover and proving the circuit is dead
we're going to need to check our voltage
indicator on a proving unit as we did in
previous presentations before we use it
so let's do that next
so before using my approved voltage
indicator to prove that the consume unit
has been isolated i need to check it
first of all on a proven unit or a known
supply the easiest thing to use is a
proven unit as i probe into my proving
unit you should see the lamps illuminate
on it suggesting it is working correctly
like so
once we've done that we can remove it
and we can take it into installation and
use it to prove safe isolation so we've
now got the complete consumer unit
turned off we genuinely believe the top
of the switch is possibly isolated from
the remote linked main switch which was
secured signed and padlocked off but
we've still got to prove that the top of
the linked main switch is isolated
before we start working here we're going
to use our approved voltage indicator
which we've checked before using and
we're going to do an exactly the same
sequence as we did when we rechecked
supply polarity however this time we
don't expect any illumination of the
instrument at all because the
installation should be dead so as
previously stated in one of my
presentations we're going to probe on
the appropriate order the least
dangerous conductor first so i'm going
to test between line and neutral first
i'm going to probe onto the neutral
conductor first then the line then i'm
going to remove it from the line and
then the neutral this time we do not
expect the instrument to illuminate so
therefore it would be dead when we
recheck supply polarity we're expecting
at this stage to illuminate but we've
isolated the supply so we're looking for
it to be dead so no illumination of the
instrument itself so if i probe on first
of all onto my neutral conductor and
then onto my line we can see that the
lamps are not illuminated suggesting
it's dead we pull off the line and we
pull off the neutral next i'm going to
probe onto the neutral and the earth bar
this time i'm going to probe onto the
earth bar first and the neutral bar
second so we're going to probe on first
of all if i keep my arms out the way i'm
going to probe onto the earth bar
and onto the neutral and we see that it
isn't illuminated we pull off the
neutral we pull off the earth bar
finally we're going to test between line
and earth bar once again going on the
least dangerous conductor first
being the earth bar
and the line
pull off the line
and pull off the earth bar by doing all
three stages we've proved the supply
coming into this distribution board or
consumer unit has been isolated yet
we're not ready to work on the system
just yet one final check of our approved
voltage indicator before we work on it
in case this has become damaged or
faulted during the process we need to
prove again that this is in good working
order before we come back into the
consume unit itself so to prove that my
voltage indicator has not become damaged
or faulty during the process i need to
put it back into my proving unit and
prove it's in good working order only
after completing this test on the
instrument can i suggest that the
consumer unit is isolated and safe to
work in so as i probe it in i expect to
see all the lamps illuminate so it's
still in good working order suggesting
that i have proved the safe isolation of
the consumer unit therefore it's now
safe to work in that unit having
rechecked our proven unit we're now
happy that we can work inside the
consumers unit itself it's fully
isolated from the linked main switch in
the tails that is locked off the keys
are in my pocket there is a sign present
suggesting the supply has been turned
off and we can now go about
doing tests adding an additional circuit
to the consumer unit safely
i hope this video has been some help