EXTRACT: Types of procedures

As indicated in the technical standard CEI 11-27, the procedures are divided into 3 main types:

a. EXERCISE PROCEDURES

b. WORK PROCEDURES

c. MAINTENANCE PROCEDURES

A. Operating maneuvers

The operating maneuvers are of two types:

1. Manoeuvres intended to modify the electrical state of a system by means of components or equipment, connections, disconnections for starting or stopping electrical appliances designed to be used without risk as far as technically possible
2. Manoeuvres for putting equipment out of service or back into service for work on the systems.

Type of operation: Decommissioning before work without voltage or recommissioning after the same

Attendant: PES or PAV

Emergency: PES or PAV

Other maneuvers: Persons trained and authorized by RI

A1. Plant decommissioning

1. Section off the part of the system you are working on.
2. Take measures against the inadvertent re-closure of disconnect devices.
3. Make sure the system is off.
4. Earth and short-circuit the sectioned parts in HV and MV and, where required, also in LV.
5. Provide protection for any adjacent live parts.

In low and very low voltage systems, earthing and short-circuiting are not necessary, except when there is a risk that the system will be energized, for example:

• on overhead power lines intersected by other lines or electrically influenced;

if there are uncertainties in the correct identification of all the points of possible power supply of the live parts or in the effectiveness of the measures adopted to avoid untimely re-closure of the sectioning devices.

When working on overhead lines (in bare conductors or in cable) with nominal voltages up to 1000 V AC, all conductors must be earthed as close as possible to the workplace, including the neutral conductor as well as control and switching conductors, for example on mixed overhead lines for street lighting. In any case, all conductors specified above must be earthed and short-circuited.

A2.Functional checks

Functional checks must be performed by “measurements” of physical data within electrical systems.

Measurements in the presence of electrical risk must be carried out only by PES or PAV or, excluding measurements in live work, by PEC only if supervised by PES or PAV.

When taking measurements on electrical installations, suitable and safe measuring instruments must be used, constructed in accordance with the specific Product Standards. Such instruments must be checked before use and, if necessary, after use.

Type measure 1

- The open switchboard has a degree of protection towards active parts ≥ IPXXB.

- Taking into account the type of probes used (size and shape of the bare contact tip) and the distance of the active parts from each other and from the masses, there is no risk of accidental contact or accidental short circuit.

No PES supervision is required, insulating gloves and short circuit protection visor are not required.

Type measure 2

- The open switchboard has a degree of protection towards active parts < IPXXB.

- Taking into account the type of probes used (size and shape of the bare contact tip) and the distance of the active parts from each other and from the masses, there is a risk of accidental contact but there is no risk of accidental short circuit.

The measurement must be carried out by PES or PAV suitable for working under voltage, equipped with insulating gloves, but without the visor for protection against short circuits.

Type measure 3

- The open switchboard has protection against active parts < IPXXB
- Taking into account the type of probes used (size and shape of the bare contact tip) and the distance of the active parts from each other and from the masses, there is no risk of accidental short circuit. There is a risk of accidental contact with accessible active parts in proximity (as an alternative to insulating gloves, the active parts must be made inaccessible with a protection, for example an insulating sheet).

Type measure 4

- The open switchboard has a degree of protection towards active parts < IPXXB.

- Taking into account the type of test leads used (size and shape of the bare contact tip) and the distance of the live parts from each other and from the masses, there is a risk of accidental contact and accidental short circuit.

The measurement must be carried out by PES or PAV suitable for working under voltage, equipped with insulating gloves, a visor for protection against short circuits, a helmet and suitable clothing.

A3. Evidence

Tests include all operations intended to check the functioning or electrical, mechanical or thermal state of an electrical system.

The tests must be carried out by PES or PAV (if necessary, with suitability for live work in LV) or by PEC only if under the supervision of PES or PAV or the supervision of PES with regards to work without voltage or in the proximity of live parts.

Tests with external power source

• Disconnect the system from all sources of possible normal power supply.
• Make sure that the system cannot be re-energized from any power source other than the external one in use.
• Take all necessary safety measures against electrical risk for all personnel present.
• Ensure that the separation points have adequate insulation characteristics to withstand the simultaneous application of the test voltage on one side and the operating voltage on the other.

A4.Inspection

Verification procedure

Visual examination.

Inspections must be performed by PES or PAV with experience in inspecting similar systems (already in operation). Inspections must be performed with suitable equipment in order to prevent hazards, also taking into account, if necessary, the limitations imposed by the presence of live parts.

The results of inspections shall be recorded. Corresponding and appropriate corrective actions shall be taken where necessary and the results recorded.

B. Working procedures

B1. Planning

The PL must notify the RI of the nature, location and impact on the electrical system in relation to the work to be carried out.

RI authorizes PL to begin work

B2.Specific requirements regarding atmospheric conditions

When working under tension, outdoors or indoors, in the event of atmospheric conditions that limit visibility or reduce insulating properties, the PL is left to assess whether it is necessary to suspend the work itself.

In such circumstances, the PL must take all necessary measures to leave the plant and equipment in a safe state, including with respect to third parties; personnel must leave the workplace in a safe manner.

B3. Requirements in case of induction or transfer of earth potential

Earth connections at adequate intervals to reduce the potential between conductors and earth to a safe level.

Equipotential connections in the workplace to avoid the possibility of operators entering an induction loop.

B4. Requirements for outdoor work

Conditions where outdoor work is prohibited

• In case of rain or snow.
• In case of thunderstorms.
• In the presence of strong winds.
• At low temperatures.
• With poor visibility.




B5. Prescriptions for interior work

In indoor work, there is no need to take atmospheric conditions into account if the installation is powered by a network entirely in underground cable or is adequately protected against overvoltages of atmospheric origin. However, live work is prohibited when carried out in wet environments.




B6. Work without voltage

Basic prescriptions

• Section off the part of the system you are working on.
• Take measures against the inadvertent re-closure of disconnect devices.
• Make sure the system is off.
• Earth and short-circuit the sectioned parts in HV and MV and, where required, also in LV.
• Provide protection for any adjacent live parts.




The identification of underground LV or MV cables, especially in the presence of other similar cables in the same excavation and path, is an operation that requires particular attention. In these cases, after having de-energized and secured the cable at the ends, in the points where its identification is certain, e.g. in the cabin, you can proceed as follows depending on the system:

- on LV lines, by checking for the absence of voltage with specific instruments and equipment (e.g. with the use of insulation piercing terminals) or by cutting at the point where you want to intervene on it;

- on MT lines, through cutting, which must be carried out with cable-cutting shears with insulation suitable for the operating voltage of the cable, built according to the relevant product standards (e.g., for voltages up to 30 kV, according to the CEI EN 50340 standard).

In any case, cutting is also valid as a check for the absence of voltage on the system.

The approval to start the work must be given to the workers exclusively by the PL who is responsible for safety in the execution of the work, after having implemented the measures of his competence described above. Each person employed in the activity must be PES or PAV or must be under the supervision of a PES.

B7. Working under low voltage (categories 0 and I)

This procedure is only valid for category 0 and I systems (Voltage ≤ 1000 V AC and 1500 V DC).

Personnel working under voltage must be PES or PAV and have obtained the suitability for working under voltage on category 0 and i systems. This suitability must be certified and issued by the employer (DDL).

The Employer is responsible for certifying suitability for live work on Category 0 and I systems.

To obtain the qualification, the person must possess theoretical knowledge for live working at level 2A and practical knowledge at level 2B.




B8. Low voltage working methods

A. Working with insulating rods

The operator must use only insulating rods to come into contact with the live part.

B. Work with insulating gloves

The operator comes into contact with the active part using insulating gloves.

Live contact work




• The parts with different potential (phases, neutral, masses) in the part of the system on which the work is being carried out must be separated by insulating screens (partitions, insulating tapes or bands, insulating mastic, etc.) to avoid the risk of accidental short circuits and consequent electric arc.
  
• The condition of the components on which work is carried out under tension must be such as to exclude the risk of breakages and movement of the live metal parts and the risk of short circuits.
  
• Moving live parts, such as uninsulated cable ends, must not be left by the operator until they have been insulated or secured.




To carry out work under contact voltage, the operator must wear the following Personal Protective Equipment to protect against electrical risks:

- insulating gloves,
- protective visor,
- insulating helmet;
- suitable clothing that does not leave parts of the trunk and limbs uncovered.




B9. Bare-handed work

The operator must keep himself at the same potential as the active part on which he operates.




Working under tension with bare hands

• The work area must consist of a clearly identified area.
• It must not be possible for operators to touch, even outside the work area, parts with a different potential (for example the ground or masonry or concrete buildings, etc.).
• Operators must be placed on insulated or metal platforms equipped with metal guardrails, isolated from the ground. Metal platforms must be permanently connected to the live part before the part itself is touched by operators. Equipotentiality of all metal parts connected to the platform must be ensured.
• No physical connection is permitted between the platform and other parts at different potentials other than those made with insulating rods or ropes. The insulation of the platform from the ground must be checked with appropriate periodicity.

B10. Exclusions from live work

The following operations carried out on electrical systems or equipment under voltage even above 1000 V AC and 1500 V DC, carried out in compliance with the relevant technical standards, provided that equipment and procedures compliant with the technical standards are used and the personnel is adequately trained and instructed, do not constitute live work regulated in the CEI 11-15 standard:

- operation of sectioning, interruption and regulation devices and of fixed earthing and short-circuiting devices, under normal operating conditions;
- operation of the above-mentioned devices using insulating rods, under normal operating conditions;•use of voltage detectors and comparators, constructed and used under the conditions specified by the manufacturer or by the product standards themselves;
- use of insulating distance detectors under the intended conditions of use;
- washing of insulators carried out by fixed automatic or remote-controlled systems; •use of mobile earthing and short-circuiting devices;
- jobs in which work is carried out on components that are part of machines or equipment powered by a voltage not exceeding 1000 V AC even if they operate at a higher voltage.

Furthermore, the use of equipment and tools during operations relating to tests, fault finding, etc., which can technically only be carried out in the absence of earthing and in the short circuit of live parts which have been de-energised, does not constitute live work, provided that, following a risk analysis, test procedures (or methods) are adopted, aimed at preventing the aforementioned live parts from being re-energised by any possible power source (see also section 5.3.2).



B 11. Operating modes

The choice of the method of carrying out the work is the responsibility of the PL, based on the characteristics of the system, the nature of the intervention, the personnel in possession of the required qualifications made available, the PPE supplied, etc.

When assessing whether to carry out work under voltage, the presumed short-circuit current at the point where the work is being carried out and the intervention time of the upstream short-circuit protection device (fuses, current-limiting switches, etc.) must also be taken into account.

Personnel carrying out work under tension must possess all the requirements set out in this technical standard.

Before carrying out live work, it is necessary that the RI and the PL, each for their own competences, proceed, working in collaboration, to prepare the work, providing for the consequent safety measures. The work area, which in live work is dangerous as it contains the active part on which it is necessary to intervene, must be clearly delimited in the presence of PEC. Warning signs must also be posted prohibiting access to unauthorized persons. Only the PL and the persons authorized by him are allowed in the work area.




B12. Work organization




RI Tasks

1. Draw up the work plan.
2. Place and maintain the system in the condition envisaged by the work plan.
3. Identify the work area.




PL tasks to be performed before starting the execution of the works

1. Agree with RI on the methods of carrying out the work.
2. Verify that the work can be performed in compliance with the regulations and company procedures.
3. Verify that there are no live parts accessible at a distance less than_v within the area in which the operation is taking place.
4. Check that any metal parts not protected against direct contact are not live.
5. Check that the collective equipment is efficient.
6. Verify that the person carrying out the work uses the required protective equipment and tools.
7. Communicate specific information about the work to be done to workers.
8. Check for RI notification for the start of work.

Work near live parts

In the case of work in the vicinity of live parts of any nature, it is necessary to adopt safety systems such as screens, barriers, enclosures, insulating protectors, provision of safety distances, provision of supervision and/or surveillance.

Proximity work must be carried out by PES or PAV. Ordinary persons (PEC) may carry out proximity work provided that a PES manages the electrical risk through supervision or surveillance (the latter may also be carried out by a PAV).


C. Maintenance procedures




Maintenance work is of two types:

• work where there is a risk of shock, short circuits or electric arcs and therefore the appropriate working procedures described in the previous paragraphs must be applied;
• jobs where the design of the equipment allows for maintenance without electrical risk.




All maintenance procedures to be performed must be approved by the Electrical System Manager (URI or RI).

The personnel carrying out the work must be PES or PAV and suitable for working under tension, when necessary.




C1. Temporary interruptions

In case of temporary interruptions of maintenance work, the PL must take all necessary measures to prevent access to live parts and unauthorized operation of the electrical system. If necessary.

Inform RI of any disruption.




C2. End of maintenance work

At the end of the maintenance work, the Maintenance Supervisor must deliver the system to the RI. The status of the electrical system undergoing maintenance must be notified to the RI.

More information for safe working

Example of levels of responsibility

General scheme

Example of division of roles in the organization of electrical work carried out in system element 3 and which involves interventions/maneuvers on other system elements located within the areas with a green background delimited by dotted lines. In order to carry out electrical work in system element 3, interventions were necessary that involved:

- partially the system elements 4 and 5 (the elements not subject to interventions/manoeuvres remain in “normal operating” configuration and therefore remain under the responsibility of URI);
- the entire system element 2.

Therefore, the areas with a green background have been subject to manoeuvres/interventions by RI (b) which assumes the responsibility of guaranteeing their safety for the entire duration of the works.

Element 3 and the surrounding area with a yellow background, identified as the “work station”, are handed over to the PL (c) who, by coordinating the workers (d), will assume responsibility for the safe execution of the work itself. The entire white area, which includes the entire element 1 and part of elements 4 and 5, have not been affected by interventions/manoeuvres, therefore it maintains the status of “normal operation” and remains under the responsibility of URI (a) as it is not involved in electrical work. As can be seen, the role of URI is not involved in the organisation of electrical work.

The URL figure, in the case of particularly complex jobs from an executive and/or organizational point of view, has the responsibility of preparing the work and sharing it with the PL who will lead it in the field. In simpler jobs, it coincides with the person who covers the role of PL.




House

URI classification): owner

Classification RI), PL) and Workers): electricians

Small business or craftsman

URI classification: owner (e.g. baker owner of bakery)

Classification RI), PL) and Workers): electricians

Large industrial company

URI Classification): Employer or executive staff or those responsible for overall electrical systems

RI classification: person designated to act as manager of an electrical system during work activities

PL classification): head of a team in your own company or a third party company

Classification of workers: members of the work team