Electrical Hazards
5. Prevention and Protection Measures
5.1. Informative safety measures
The term informative measures is given to those measures that somehow prevent the existence of risk. These may be:
Regulatory: consisting in establishing operational rules of a specific nature for each job or general coordinates with the other informative measures.
They may be personal or general.
Instructive: consisting in training those who work with electric hazards regarding the way to correctly use the devices and tools they handle and the meaning of symbols and signs.
Signposting: consisting in the positioning of forbidden, warning or informative signs in the appropriate places.
Identification and detection: consisting in the identification and checking of voltages in electrical installations before working on them.
5.2. Protection measures
Personal
Within this group, we may consider insulating gloves, insulating helmets, insulating stools and mats, manipulation and rescue rods, insulating footwear, etc. These will have to comply with the essential health and safety requirements and thus carry the CE mark.
Of the Installation
We may consider these to be divided into two groups:
a) Protection against direct Contact
Based on the following principles:
- A layout that impedes the electric current from passing through the human body.
- Limiting the current that can pass through the human body to a non-hazardous intensity (< 1 mA).
Within this group, we include the most important measures contemplated in Complementary Instructions MIE-BT-021 of the Low Voltage Regulations:
- Separating by a distance or distancing active parts.
- Placing obstacles or barriers.
- Covering or insulating active parts.
b) Protection against indirect Contact
Within this group, we consider the measures grouped into: Class A Systems and Class B Systems, on the basis of the following principles:
Class A Systems
- A layout that impedes the current from passing through the human body.
- Limiting the fault current that can pass through the human body to a non-hazardous intensity.
Class B Systems
- Automatic cut-off when a fault appears that is susceptible to favouring the passing of a current considered hazardous through the human body in the case of Contact with grounds.
Class A protection measures include:
- Separating circuits.
- Using small safety voltages.
- Separating accessible active parts and grounds by means of protective insulation (double insulation).
- Simultaneous inaccessibility of conducting elements and grounds.
- Covering grounds with protective insulation.
- Equipotential connections.
Class B protection measures include:
- Earthed grounds and fault current intensity cut-out device.
- Fault current intensity cut-out devices.
- Neutral grounds and fault current intensity cut-out device.
- Earthed grounds and fault voltage cut-out devices.
- Circuit-breakers.
