Electrical Safety

A typical laboratory may house a large number of appliances that pose electrical hazards. Examples include: power supplies, microwave devices, ovens, stirrers, heating mantles (in say, distillation apparatus), pumps, compressors, sonicators, etc. In addition, some laboratories may need to house equipments that require high voltage / power for operation. Also devices which embody capacitors are hazardous as they may allow storage of high levels of electrical energy which may discharge accidentally. All electrical devices need to be maintained and operated following safe practices; in absence of either precautions such equipments may pose serious hazards to an user, which in the worst case may prove fatal.

The major hazards associated with electricity are electrical shock and fire. In a flammable atmosphere electrical equipment discharges cause fires and/or explosions. On the human body, the severity and effects of an electrical shock depends critically the magnitude of current, the duration of exposure to the shock. Since water is a good conductor, the effects are intensified if a contact with an electrically energized source is made with a wet skin. Electrical shocks may have minor to major consequences: a shiver to severe burns, and in the extreme case a cardiac arrest.
The table 5 below shows the range of response that the human body to current.

 Table 5 Current Intensity and Human Response

Current (milli-amperes)



Perceptible magnitude


Experience of mild shock (not painful)

6 – 30

Feeling of pain

30 – 150

Severe muscular convulsion, Extreme pain, Respiratory seizure,

1000 - 5000

Ventricular fibrillation

> 10000

Cardiac failure, severe burns, probable fatality

Typical measures to control laboratory electrical hazards are:

  • Ensure all electrical equipments are appropriately grounded; provided with suitable insulation, and guarded so as to avoid direct contact; conduct periodic checks to ensure
  • the integrity of such measures
  • Ensure adequate signage to indicate the location of main power supply which must be deactivated in case of any emergency
  • In case it is needed to handle equipments that are connected to electrical power source, avoid contact through wet skin
  • Use personnel protection such as non-conducting gloves and shoes when handling electrical equipments that are energized
  • Be sure to disconnect the power source before repairing / removing electrical equipment
  • Avoid using both hands while at work with electrical equipments, as bridge formed by using both hands increases the chance of respiratory shock
  • In case of accidental receipt of electrical shock by a person, first switch off /disconnect the power source before touching the person or any part of the electrical system which relayed the shock
  • In case of accidental spillage of a chemical onto an electrical equipment disconnect the electrical supply source prior to any cleanup
  • In cold rooms condensation may increase the chance of electrical shock due to most conditions; hence it is desirable to minimize the use of electrical equipment in such rooms
  • Modifications to existing electrical service in a laboratory or building must be subject to expert consultation and conform to standards
  • Ensure that power loss doest not create hazardous situations in a laboratory
  • Personnel handling high voltage/current equipment must be adequately trained on the prospective hazards

For additional information see “Chemical, Fire and Electrical Safety Document” from WHO available at: http://whqlibdoc.who.int/publications/2004/9241546506_partVI.pdf