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E L E CT R I C AL CONNE CT I ON
AUTUMN 2 01 5
LETTERS TO THE EDITOR
Dear Paul,
I have just read your article on the Infinity
Cable debacle (
Electrical Connection
Summer 2014, page 20). As an end user, the
fact that liability rests with the installer is
very confronting.
Almost every day we see imported
electrical items that do not look like they
comply with our standards. If you follow
through with making a complaint or giving
the relevant government body information
regarding non-compliant product, it takes
months to see any sort of result, if any
occurs at all.
I was recently called to repair some
lighting in a small vet clinic. Someone had
installed 36W to 28W T5 converters. Two of
these fittings had failed after less than two
years. Apart from the fact that any minute
power savings had been nullified by my call
out and materials cost, I pulled one of the
adaptors apart to see what the fault was.
I must say I was very concerned to
see a long circuit board stuffed inside an
aluminium extrusion insulated by a thin
plastic wrapped around the PCB. The
PCB was burnt out and the insulation
was damaged to the point where there
was no insulation between the 240V
and the aluminium body. The other area
for concern is that the wiring from the
tombstone pins to the PCB were not
double insulated and exposed to the
aluminium body.
This means that a fault in that adaptor
could quite possibly make the body of
the adaptor live. This poses a severe
electrocution risk as an unqualified person
could quite easily mistake the lights being
off as being isolated. In fact, you have to
disassemble the fitting to prove that the
fitting is de-energised.
An attempt has been made to double
insulate these fittings but it is not complete
and these adaptors should be earthed,
which is impossible. In my opinion these
fittings are extremely dangerous and
should be recalled or removed from
the market.
We must have better regulators and
tighter inspection and conditions. The
Infinity Cable debacle should be a wake-up
call and action must be taken as soon as
possible to make it easier to report and
more timely for these non-complying
products to be removed.
-Bill Larkin
Dear Paul,
I am extremely worried by a suggestion
made on page 33 of the Summer 2014
edition of
Electrical Connection
. In the
article ‘Setting Up Shop’ by David Herres,
he suggests making up an anti-static
wristband using a piece of wire to
connect a metal band to an earthed socket.
All anti-static wristband leads should
have a 1MΩ resistor in series built into
the lead.
Why? Well, consider this: You have the
earthed (no series resistance) strap on one
wrist and you touch an active conductor
with your other hand. Guess where the
electricity flows? Yes, straight through your
heart and will most likely kill you. That is
why anti-static wrist straps have the 1MΩ
resistor in series, as that way if you do touch
the mains then the current flow via the
wrist strap is too low to kill you.
We take this matter so seriously
that at my place of work we test all our
wrist straps once a month and if the
measured resistance is not in the range
900kΩ to 1.1MΩ then it fails the test and
is destroyed.
-David Williams
Revisiting wrist straps
Infinity cable... a wake up call