Building
and Estates are responsible for carrying out 5 year mandatory periodic
electrical testing of all permanent electrical installations. Anyone who
carries out live work must receive special training in the techniques
involved. No one should work on live equipment unaccompanied and live work
must be carried out in accordance with approved procedures. Before work
commences adequate screening of adjacent live conductors and earthed metal work
is imperative. Full use should be made of properly insulated tools, rubber
mats and rubber gloves. Low voltage (<250V) and medium voltage (<650V)
apparatus should be worked upon with the apparatus dead if practicable.
Maintenance of high voltage apparatus must be carried out with the apparatus completely
isolated.
Voltages
above 50 volts AC and 120 volts DC are hazardous and can be fatal. Fatal
accidents have occurred in unfavourable circumstances with only a 40V supply.
The hazards arising from the use of electrical apparatus are the risks of
electric shock, burns, fire and explosion, injury from involuntary reaction to
otherwise harmless shock, and in the microwave and ultraviolet range, radiation
damage. If batteries etc are used for low voltage supplies the terminals and
connections should be protected to avoid the danger of a short-circuit and
hence burns arising from conductors which may accidentally fall on the
battery. Electric shock can cause cardiac arrest or cessation of breathing,
either of which can be fatal.
Burns can
occur externally or internally. External burns can be caused by the passage of
an electric current through the skin or as a result of an electric arc or a
short circuit. Burns resulting from short circuits are often made worse by
pieces of molten metal, from vaporised conductors, embedding in the skin.
Internal burns are caused by the passage of electric current through blood
vessels and internal organs.
The main
causes of such accidents are the use of defective or broken equipment, faulty
connections, wrongly sized fuses and the utilisation of wiring of inadequate
load bearing capacity. If you are in any doubt concerning any of these
features in connection with any electric installation on which you work, you
should consult your Supervisor or School Electrical Adviser. Under no
circumstances should you use electrical apparatus about which you have any doubt
over safety.
It is usual
to safeguard against electrical shock by ensuring that external metal casings
of all apparatus or equipment is earthed, and so to fasten such a casing or
screen that it is impossible to touch any electrically ‘live’ parts of the
apparatus. With correctly earthed supply installations, the use of well
designed and correctly earthed commercial equipment, the risk of electric shock
should be nil. It is important to realise that certain modern items of
equipment, particularly power drills are not earthed through the casings, but
rely on efficient double insulation. Under no circumstances, therefore, should
the eternal casings of these items be interfered with. Items with defective,
especially cracked casings, should not be used but returned to a competent
electrician for repair.
Electrical
equipment which is often moved and which subjects the plug to hard wear e.g.
portable electric drills, soldering irons etc should have plugs of the shock
resistant type. Do not, for example, allow leads to pass under water baths.
On some
equipment of foreign origin the plugs are not fused. If in doubt consult the
School Electrical Adviser.
The
continuity of earth connections on portable equipment must be checked
periodically (see PAT testing). If any normally earthed equipment must be left
unearthed for some specific purpose, a notice should be attached which makes
this quite evident to any unsuspecting person.
Flexible
rubber leaders should be kept away from hot surfaces and where connections have
to be made in hot locations the cables should be suitably protected.
Particular
care is needed when electrical equipment is used near water. Outlets should be
situated as far away as possible from sinks and care should be taken to ensure
that water from condenser tubing, water baths etc does not leak onto electrical
installations and equipment.
The
maintenance of equipment and wiring is a high priority. Any suspected fault
should be reported to the School Safety Officer immediately.
- All staff
and students are expected to be vigilant about the safe condition and
operation of equipment.
- The use
of extension leads and multisockets is discouraged.
- The use
of privately owned equipment/appliances and extensions leads is
discouraged. Such equipment must undergo testing before use. This
equipment should be entered in the School inventory for insurance and
audit purposes. The University insurance will only cover such equipment
that is directly required for work, non-authorised equipment is the
responsibility of the owner and he/she is personally liable for any
damage, accident, injury or death resulting from its use.
- Plug tops
with suitably rated fuse should normally be fitted by qualified technicians
only.
- Faults to
permanent wiring and 13A sockets etc, must be notified to the Laboratory
Superintendent or School Safety Officer. The fault must be made safe by
switching off the supply to the immediate area if possible.
- Special
care must be taken when using electrical equipment in the vicinity of
flammable vapours. Precautions must be taken to ensure the equipment is
spark-proofed. This especially applies to fridges and freezers.
- Staff and
students are expected to operate equipment in a safe manner.
- Earth
leakage circuit breakers or RCCBs should be used when equipment is
operated under adverse conditions eg. in damp or cold areas; seek advice
from the School Electrical Adviser.
- Supervisors
should risk-assess new equipment and apparatus built in-house; taking into
account instructions and safety data that come with relevant components.
Such equipment should be safety assessed and checked for fitness for
purpose by supervisors and signed accordingly. If supervisors do not feel
qualified to assess this, then advice should be sought from the School
Electrical Adviser or other suitably qualified person.
Repairs of
equipment must only be carried out by the qualified technicians. Faulty
equipment should be reported to the School Safety Officer, who will arrange for
the repair.
On no
account should research workers attempt electrical repairs of any type
including the replacement of 13 amp plugs. Any item of electrical equipment
which is considered faulty or in need of any minor repair MUST be handed to the
technician in charge of the laboratory.
Under the
Electricity at Work Regulations 1989 all electrical equipment and appliances
used within the School must be tested at recommended intervals. The technician
responsible for the laboratory carries this out. A green label will be
attached to the equipment stating date of test and when the next test is due. Test
frequency is as follows:
- Every 6
months for high risk equipment eg. portable hand tools
- Every 12
months for portable laboratory equipment
- Every 2
years for large laboratory equipment
- Every 3
years for IT equipment
Check all
equipment that you use has a valid electrical test label before use. The
technician responsible for the laboratory should be informed immediately of any
equipment that is out of test date. Do not use such equipment.
Any item
that has failed the PA test or is faulty should be labelled accordingly and
taken out of service immediately.
