Safe Isolation
It cannot be
over-emphasized how important it is that isolation of electrical circuits is
carried out in a set sequence, and that this sequence is repeated each time a
circuit or complete installation is to be isolated.
If the same
procedure is followed each time isolation is carried out, it will soon become a
habit, which can only be a good thing as it may save your life.
It is vital
that the correct test equipment is used for isolation and that it complies with
the Health and Safety Executive document GS 38. This document gives guidance on
the use of test equipment, particularly leads and probes.
The GS 38
document is not a statutory document but if the guidance given in the document
is followed, it will normally be enough to comply with the Health and Safety at
Work Act 1974, the Electricity at Work Regulations 1989 and any other statutory
requirements that may apply.
The items of
equipment that should be available to persons carrying out the safe isolation procedure
are:
Isolation
procedure
It is very
important to ensure that the circuit that you want to isolate is live before
you start. To check this, a voltage indicator/test lamp or a piece of equipment
that is already connected to the circuit should be used. If it appears that the
circuit is already dead, you need to know why.
• Is
somebody else working on it?
• Is the
circuit faulty?
• Is it
connected?
• Has there
been a power cut?
You must
make absolutely certain that you and you alone are in control of the circuit to
be worked on. Providing the circuit is live you can proceed as follows:
STEP 1
Ensure
voltage indicator/test lamp is working correctly.
STEP 2
Test between
all live conductors and live conductors and earth.
STEP 3
Locate the
point of isolation. Isolate and lock off. Place warning notice (DANGER
ELECTRICIAN AT WORK) at the point of isolation.
STEP 4
Test circuit
to prove that it is the correct circuit that you have isolated.
STEP 5
Check that
the voltage indicator is working by testing it on a proving unit or a known
live supply.
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