College of Medical, Veterinary and Life Sciences
Institute of Molecular, Cell and Systems Biology
Electrical Safety
The following information and instructions supplement the Safety Policy for the Institute,
and are key elements to ensure that the Safety Policy is implemented effectively.
The University of Glasgow has the responsibility to inform its employees of the electrical
hazards that may be encountered in the workplace.
Hazards Involved
Electrical apparatus in laboratories is frequently associated with other hazards such as
water, corrosive, or flammable materials potentially resulting in fire or explosion.
High levels of electrical stimulation in contact with the human body can cause the heart to
go into a state of fibrillation (disorganised contractions) in which it ceases to pump blood.
Precautionary Measures

Ensure that portable appliances in use in the laboratory are in good condition.

Do not use any equipment in a manner that breaches manufactures’ instructions.

Select equipment suitable for the environment in which it is to be used

Remove as far as is possible any external hazards from the work area.
The majority of common faults to equipment can be detected by a visual check without
special equipment. Damaged equipment should be clearly labeled as soon as it is known to
be unsafe and this is every user's responsibility. A step-by-step guide for visually checking
electrical equipment is available from the University’s Safety Office website at
http://www.gla.ac.uk/services/seps/electricalsafety/.
Portable Appliance Testing (P.A.T)
The Institute is committed to a regular schedule of portable appliance testing.
Electrophoresis equipment and power packs
Electrophoresis is a separation method which uses electrical energy to separate molecules
such as proteins or nucleic acids by their size or electrical charge. The power supplies
operate at up to several thousand volts or currents of up to 500mA. This is potentially
hazardous and a prominent safety warning sign should be used to indicate when the
apparatus is live, even if protected by a micro-switch.
The potential for injury arises because not only are large quantities of electrical energy
involved but because the supporting medium is commonly immersed in either saline or
buffer.
The physiological effect of DC currents of 10-100 mA include muscular paralysis and
potentially lethal cardiac fibrillation. Such currents are within the output range of most
power packs and are typical of contacts made through wet skin.
Guidance Notes on Electrical Safety
Page 2 of 2
All equipment operating on less than 300 V DC is to be provided at least with the enclosing
cover labeled 'Danger of Electric Shock' when in use and preferably to have the mains
supply interrupted by a micro-switch or a physical interlock connected to the cover.
Equipment using more than 300 V DC MUST be protected by a micro-switch-controlled or
physically interlocked cover.
To minimize danger:

Make sure mains power is OFF before handling apparatus

Handle leads with only ONE HAND and handle ONLY ONE LEAD AT A
TIME. Do not Touch well-earthed objects (e.g. water-taps, other electrical
appliances) whilst in contact with live apparatus.

Cold-room circuits should be protected by an earth leakage circuit breaker
(ELCB).
A safe system of work for electrophoresis requires that power supplies to tanks are always
switched off before the lid of the tank is opened. In addition, supplementary protection by
interlocking the power supply is necessary to ensure that anyone who forgets to switch off
is not at risk. Effective interlocking may be provided by well shrouded sockets on the tank
lid which are permanently connected to the DC supply connector and which separate from
the corresponding contact pins on the tank body which are connected to the electrodes.
Thus opening the tank lid automatically removes the power. There can also be power
interlocking using a positive mode safety switch on a tank with a hinged lid arranged to
break the AC supply to the power pack when the lid is opened. There can also be a safety
interlock circuit for connection to the tank switch incorporated in the power pack itself.
Simple control circuit interlocking with a safety switch to operate a contactor or relay
which breaks the AC supply to the power pack when the lid is opened is not recommended.
The risk with this system is the possibility of a contactor or relay sticking in the closed
position, and the indicating lamps even if provided being ignored by the operator.