Electrical Hazards & Control

What is electricity?

Electricity is the flow or movement of electrons through a substance which allows the transfer of electrical energy from one position to another.

Direct Current (dc) – involves the flow of electrons along a conductor from one end to the other.

Alternating Current (ac) – is produced by a rotating alternator and causes an oscillation of the electrons rather than a flow of electrons so that energy is passed from one electron to the adjacent one and so on through the length of the conductor.

Conductors are nearly always metal, copper being the most popular as it is a very good conductor but can also come in gases or liquids i.e. water. Poor conductors are known as insulators and include materials such as rubber, timber and plastics.

Equipment and the electrical supply are joined together by a circuit, should this circuit be broken the electrical flow will go directly to earth and the equipment will stop working, this is known as a short circuit.

Low Voltage – a voltage normally not exceeding 600 volts ac between conductors and earth or 1000 volts ac between phases. Mains voltage falls into this category.

High Voltage – a voltage normally exceeding 600 volts ac between conducters and earth or 1000 volts ac between phases.

Main Voltage – this is the common voltage available in domestic premises and many workplaces and is normally taken from 3 pin socket points. In the UK it is distributed by the national grid and is usually supplied between 220 V and 240V, alternating current at 50 cycles.

Maintenance – a combination of any action carried out to retain an item of electrical equipment in, or restore it to, acceptable and safe condition.

Testing – a measurement carried out to monitor the conditions of an item of electrical equipment without physically altering the construction of the item or the electrical system to which it is connected.

Inspection – a maintenance action involving the careful scrutiny of an item of electrical equipment using all senses to identify whether or not the equipment is of safe condition.

Examination – an inspection together with the possible partial dismantling of an item to ensure that the equipment is fully safe to use.

Isolation – this incolves cutting off the supply of electricity from all or a dicrete section of the installation by separating the installation or section from every source of electrical contact.

Electrical Hazards & Injuries

Electricity is safe, clean and a quiet method of transmitting energy, however when this source for energy comes into contact with conducting material such as people, animals or metals then this can result in loss of life or serious damage.

The main hazards associated with electricity are

• Electric shock
• Electric burns
• Electrical fires and explosions
• Arcing
• Portable electrical equipment
• Secondary hazards

Electric shock & burns

Upon finding somebody who is suffering from electric shock you should:

• Raise the alarm, by calling for help
• Switch off the power, if possible
• Call for an ambulance
• If it is not possible to turn off the power, then push or pull the person away using insulatable material i.e. wood. Remember to stand on dry material such as a wooden pallet. If this precaution is not taken then the rescuer will also become electrocuted
• If the person is breathing put them into the recovery position so that the airway is kept clear and the mouth can drain if required
• If the person is not breathing then apply mouth to mouth resuscitation and, in the absence of a pulse, chest compressions. If they are breathing normally then place them in the recovery position
• Treat any burns by placing a sterile dressing over the burn and secure with a bandage. Any loose skin or blisters should not be touched nor any lotions or ointments applied.
• If the person regains consciousness then treat for normal shock
• Remain with the person until they are taken to the hospital

PAT testing

All portable appliances are subject to variety of tests, these are

• user checks – before every use
• a formal visual inspection – to be scheduled in accordance with your maintenance schedule and H & S Policy
• combined inspection & test – to be carried out by a competent person usually an external contractor

User Checks

Before using any portable appliance you should always carry out a number of checks

• Is there a recent protable appliance test (PAT) label attached to the quipment?
• Are any bare wires visible?
• Is the cable covering, undamaged and free from cuts and abrasions (apart from light scuffing)
• Is the cable too long or too short? (does it present a trip hazard)
• Is the plug in good condition, for example, the casing is not cracked and the pins are not bent
• Are there no taped or other non-standard joints in the cable?
• Is the outer covering of the cable where it should be i.e. no coloured wires are vsisible?
• Is the outer casing of the equipment damaged or loose?
• Are there overheating or burn marks on the plug, cable, sockets or the equipment/
• Are trip devices working effectively i.e. RCD adaptors

Formal visual Inspections & tests

• Is the polarity correct?
• That the correct fuses are being used?
  
• That all the cables and cores are effectively terminated?
• That the equipment is suitable for its environment

User checks should be made every time before use and formal inspections and testing should be carried at regular intervals in accordance with your risk assessments, for example the harsher the working environment is the more frequent tests should be carried out as it stands to reason that the equipment will be used more on a construction site than in an office block.

Records should be kept of all inspections and tests made and should be kept up-to-date at all times.

Pro’s & Cons of PAT testing

Pro’s

1. Earlier recognition of potentially serious equipment faults, such as poor earthing
2. Discovery of inappropriate electrical supply
3. Discovery of incorrect fuses being used
4. The misuse of portable equipment can be monitored
5. An increased awareness of hazards linked to electricity

Cons

1. Some fixed equipment is tested too often leading to excessive costs
2. Some unauthorised equipment is never tested i.e. personal microwaves and kettles so remain a hazard
3. The competence of the tester is sometimes not high enough
4. Faults are not followed up in appropriate time frame so hazards remain in the workplace