Close cooperation between safety officers and local fire prevention officers from Facility Dept. in Alfaisal University is essential.
Electrically power-driven equipment, such as hot plates, stirrers, vacuum pumps, electrophoresis apparatus, lasers, heating mantles, ultra-sonicators, power supplies, and microwave ovens are essential elements of many Laboratories. These devices can pose a significant hazard to laboratory workers, particularly when mishandled or not maintained. Many laboratory electrical devices have high voltage or high power requirements, carrying even more risk. Large capacitors found in many laser flash lamps and other systems are capable of storing lethal amounts of electrical energy and pose a serious danger even if the power source has been disconnected.
The major hazards associated with electricity are electrical shock and fire. Electrical shock occurs when the body becomes part of the electric circuit, either when an individual comes in contact with both wires of an electrical circuit, one wire of an energized circuit and the ground, or a metallic part that has become energized by contact with an electrical conductor.
Apart from chemical hazards, the effects of fire on the possible dissemination of infectious material must be considered. This may determine whether it is best to extinguish or contain the fire.
The assistance of local fire prevention officers in the training of laboratory staff in fire prevention, immediate action in case of fire and the use of fire-fighting equipment is desirable.
Fire warnings, instructions and escape routes should be displayed prominently in each room and in corridors and hallways.
Common causes of fires in laboratories are:
- Electrical circuit overloading
- Poor electrical maintenance, e.g. poor and perished insulation on cables
- Excessively long gas tubing or long electrical leads
- Equipment unnecessarily left switched on
- Equipment that was not designed for a laboratory environment
- Open flames
- Deteriorated gas tubing
- Improper handling and storage of flammable or explosive materials
- Improper segregation of incompatible chemicals
- Sparking equipment near flammable substances and vapours
- Improper or inadequate ventilation.
The severity and effects of an electrical shock depend on a number of factors, such as the pathway through the body, the amount of current, the length of time of the exposure, and whether the skin is wet or dry. Water is a great conductor of electricity, allowing current to flow more easily in wet conditions and through wet skin. The effect of the shock may range from a slight tingle to severe burns to cardiac arrest. The chart below shows the general relationship between the degree of injury and amount of current for a 60-cycle hand-to-foot path of one second’s duration of shock. While reading this chart, keep in mind that most electrical circuits can provide, under normal conditions, up to 20,000 Milliamperes of current flow.
|1 Milliampere||Perception level|
|5 Milliamperes||Slight shock felt; not painful but disturbing|
|6-30 Milliamperes||Painful shock; “let-go” range|
|50-150 Milliamperes||Extreme pain, respiratory arrest, severe muscular contraction|
|1000-4,300 Milliamperes||Ventricular fibrillation|
|10,000+ Milliamperes||Cardiac arrest, severe burns and probable death|
In addition to the electrical shock hazards, sparks from electrical equipment can serve as an ignition source for flammable or explosive vapours or combustible materials.
It is essential that all electrical installations and equipment are inspected and tested regularly, including earthing/grounding systems. Circuit-breakers and earth-fault-interrupters should be installed in appropriate laboratory electrical circuits. Circuit-breakers do not protect people; they are intended to protect wiring from being overloaded with electrical current and hence to prevent fires. Earth-fault-interrupters are intended to protect people from electric shock.
General Electrical Safety
- Avoid contact with energized electrical circuits.
- Only qualified electrical workers may install, service or repair electrical equipment.
- All laboratory electrical equipment should be earthed/grounded, preferably through
- three-prong plugs.
- All laboratory electrical equipment and wiring should conform to national electrical
- safety standards and codes.
Learn the location of electrical panels and shut-off switches so power can be quickly disconnected in the event of an emergency. Be sure to always leave at least a 3-foot clearance around electrical panels for ready access.
Conduct a periodic inspection of laboratory electrical equipment to be sure it is in good condition. Remove equipment from service if in poor condition and replace or have it repaired by a qualified repair person.
Electrical outlets should have a grounding connection and accept three-prong plugs. Multiple plug outlet adapters are not allowed