Risk Assessment: Electromechanical Erection
Workers Affected by Works Hazards
RISK
161/162 Electrical Contacts.
RISK FACTORS
- Carrying out of LV and HV work.
- Work in the vicinity of LV and HV live parts.
- Erroneous or misunderstood instructions.
- When working with the typical machinery (drill presses, etc.), equipment (welding sets, etc.) and electrical hand tools (radial grinders/cutters, drills, etc.) involved in our activities.
- HV live work.
- HV live work by means of the remote working method, cleaning of circuit-breakers.
PREVENTIVE MEASURES
Rules for acting
- All work must be carried out in the absence of voltage except those jobs mentioned in sections 3 and 4 or Article 4 of Spanish Royal Decree 614/2001, namely basic operations, for instance, connection and disconnection in low voltage installations with electrical material conceived to be used immediately without any risk for the public in general; work on safety voltage installations provided that no possibility exists of confusing the identification of such installations and that the currents in a possible short-circuit do not suppose any risk of burns. Work on live installations may also be carried out: those manoeuvres, measurements, tests and checks whose nature so require it, such as the opening and closing of switches or circuit-breakers, measurement of a current, the carrying out of electrical insulation tests or checking the concordance of phases; those jobs on (or in the vicinity of) installations whose conditions of exploitation or continuity in supply so require it.
- Any operation or manoeuvre to disconnect the power supply in an installation before carrying out work in the absence of voltage and subsequent work to reconnect the installation once all the work has been completed (applying the 5 Golden Rules) is to be carried out by Authorised Workers, who, in the case of high voltage installations are to be Qualified Workers.
- Applying the 5 Golden Rules: The following steps are to be followed sequentially:
1ª. DISCONNECT THE SOURCES OF VOLTAGE:
The part of the installation where work is to be carried out is to be insulated from all power supplies. This insulation is to consist of an air gap or the insertion of an insulating element, sufficient to electrically ensure said insulation.
Condensers and other elements of the installation that remain live after disconnecting are to be discharged by means of appropriate devices.
This “power source insulation” may be carried out using:
- Switches; using only the open/closed sign on the switch control is not acceptable.
- Circuit-breakers; this manoeuvre is only acceptable when the blades are fully open.
- Fuses, which have to be extracted from their holders.
- Bridges; the separation between their ends is to be at least equal to the length of the strips of insulators and they are to be fastened to the electricity line.
As regards the concept of “electrically ensuring said insulation”, this refers to accidental, undesired closure of a cut-off element, for example:
- Involuntary actuating of the control lever of the device and closure of the switch.
- Material falling between the blades of a circuit-breaker.
- Accidental Contact in the control circuit of a switch.
