NR10 – Safety in Electrical Installations and Services

(SEPRT Ordinance No. 915, of July 30, 2019)

[Book] NR-10 Safety in Electrical Installations and Services (Annotated)
(Version 2019, with comments and explanations)

10.1 Objective and Scope

10.1.1 This regulatory standard (NR) establishes the minimum requirements and conditions aiming the implementation of control measures and preventive systems to ensure the health and safety of workers who directly or indirectly interact with electrical installations and services.

10.1.2 This NR applies to generation, transmission, distribution, and consumption, including the phases of project, construction, assembly, operation and maintenance of electrical installations and any work performed in the vicinity in compliance with the official technical standards established by the competent bodies and in their absence or omission, the applicable international standards.

10.2 Control Measures

10.2.1 Preventive measures shall be taken to control the electrical risk and other additional risks by means of risk analysis techniques to ensure health and safety at work for all interventions in electrical installations.

10.2.2 The adopted control measures shall be integrated with the other initiatives of the company to preserve the health, safety, and environment of the workplace.

10.2.3 Companies are required to keep up-to-date single-line diagrams of the electrical installations in their establishments with the specification of the grounding system and other protection devices and equipment.

10.2.4 Establishments with an installed load greater than 75 kW shall establish and maintain an Electrical Installation Documentation, containing, in addition to the provisions of item 10.2.3, at least:

a) set of procedures and administrative and technical guidelines for health and safety, implemented and related to this NR and the description of existing control measures;

b) documentation of inspections and measurements of the lightning protection system and electrical grounding;

c) specification of collective and personal protective equipment and the tools, applicable as determined by this NR;

d) documents proving the qualification, skills, training, authorization of the workers and the training conducted;

e) results of electrical insulations tests performed on personal and collective protective equipment;

f) certifications of electrical equipment and materials in classified (hazardous) areas;

g) technical reports of current inspections with recommendations, compliance schedules, covering the items (a) to (f).

10.2.5 Companies that work on installations or equipment that are part of the electrical power system shall keep a documentation with the contents of item 10.2.4 and include the following documents:

a) description of emergency procedures;

b) certifications of personal and collective protective equipment; Companies that work around the electrical power system shall keep documentation that includes paragraphs (a), (c), (d) and (e) of item 10.2.4 and paragraphs (a) and (b) of item 10.2.5.

10.2.6 Electrical Installations Documentation shall be organized and kept up to date by the employer or a person formally designated by the company and shall remain available to workers involved in electrical installations and services.

10.2.7 The technical documents provided for in the Electrical Installations Documentation shall be prepared by a legally qualified professional.

10.2.8 Collective Protective Measures All services performed in electrical installations shall foresee and adopt, as a priority, collective protective measures applicable to the activities to be performed, by means of procedures, to ensure the health and safety of workers. The collective protective measures comprise, as a priority, electrical de-energization in accordance with this NR and, if this is not possible, the use of safe working voltage. If it is impossible to implement the provisions of item, other collective protective measures shall be used, such as: insulation of live parts, obstacles, barriers, signs, automatic disconnection of supply, blocking of auto recloser. The grounding of electrical installations shall be performed in accordance with the regulations established by the competent bodies and, in the absence of such regulations, shall comply with the international standards in effect.

10.2.9 Individual Protective Measures When collective protective measures are technically unfeasible or insufficient to control risks in electrical installations, personal protective equipment specific and appropriate to the activities to be carried out shall be adopted in compliance with the provisions of NR-6. Work clothing shall be adequate to the activities, considering the conductivity, flammability, and electromagnetic influences. It is forbidden to wear personal adornments when working in or around electrical installations.

10.3 Safety in Design

10.3.1 It is mandatory that the electrical installation projects specify disconnecting switches that prevent re-energizing as well as warning signs indicating the operating condition.

10.3.2 The electrical project, as far as possible, shall foresee the installation of simultaneous action disconnecting device, which prevents the re-energization of the circuit.

10.3.3 The electrical installation project shall consider safe distances regarding the dimensioning and location of its components, and the external influences when operating and performing construction and maintenance services. The electrical circuits with different purposes, such as communication, signaling, control and traction, shall be identified and installed separately, except when the technological development allows for sharing, respecting the definitions of projects.

10.3.4 The project shall define the configuration of the grounding scheme, whether the interconnection between the neutral conductor and the protective conductor is obligatory, and the grounding of the conductive parts not intended for conducting electricity.

10.3.5 Whenever technically feasible and necessary, disconnecting devices shall be designed to incorporate permanently installed potential equalization and grounding for the disconnected circuit.

10.3.6 Every project shall foresee conditions for the use of temporary grounding.

10.3.7 The electrical installation projects shall be made available to authorized workers, the competent authorities and other persons authorized by the company and must be kept up to date.

10.3.8 The electrical projects shall meet the requirements of the regulatory standards on health and safety, the established official technical regulations, and be signed by a legally qualified professional.

10.3.9 The descriptive memorial of the projects shall contain at least the following safety items:

a) specification of the characteristics relating to protection against electric shock, burns, and other additional risks;

b) indication of the position of the electric circuits switching devices: (Green – “D”, off and Red “L”, on);

c) description of the identification system of electrical circuits and equipment, including switches, control, protection and interlocking devices, conductors and the equipment and their structures, defining how such indications shall be physically applied to the installation’s components;

d) recommendations for restrictions and warnings regarding the access of people to the components of the installations;

e) precautions applicable to external influences;

f) functional principle of the protective devices in the project, intended for the safety of people;

g) description of the compatibility of the protective devices with the electrical installation.

10.3.10 The project shall ensure that the installations provide workers with adequate lighting and a safe working position in compliance with NR-17 (Ergonomics).

10.4 Safety in Construction, Installation, Operation and Maintenance

10.4.1 The electrical installations shall be constructed, installed, operated, remodeled, expanded, repaired, and inspected in a way that ensures the health and safety of workers and users, and be supervised by an authorized professional as provided for in this NR.

10.4.2 In the referred works and activities, preventive measures shall be adopted to control additional risks, especially those related to working at height, confined spaces, electric and magnetic fields, explosion, humidity, dust, fauna and flora, and other aggravating factors, with the adoption of safety signs.

10.4.3 Only equipment, devices, and electrical tools compatible with the existing electrical installation can be used in workplaces, preserving protective characteristics, respecting the manufacturer’s recommendations and external influences. Equipment, devices and tools provided with electrical insulation shall be adapted to the voltages and shall be inspected and tested according to all existing regulations or manufacturers’ recommendations.

10.4.4 Electrical installations shall be maintained in safe operating conditions and their protection systems shall be inspected and controlled periodically in accordance with existing regulations and project specifications. Electrical service rooms, compartments and enclosures of electrical installations and equipment shall be exclusive for such purpose and shall not be used for storage or keeping any objects.

10.4.5 Workers shall be provided with adequate lighting and a safe working position in accordance with NR-17 (Ergonomics) so that they have their upper limbs free to perform their tasks.

10.4.6 The electrical laboratory and field tests or commissioning of electrical installations shall meet the requirements established in items 10.6 and 10.7 and can only be performed by workers who meet the conditions of qualification, skills, training, and authorization established in this NR.

10.5 Safety in De-energized Electrical Installations

10.5.1 Only electrical installations that have been cleared for work will be considered de-energized, by means of the appropriate procedures, following the following sequence:

a) sectioning;

b) prevention of reenergizing;

c) verification of the absence of voltage;

d) installation of temporary grounding with equipotentialization of the circuit conductors;

e) protection of the energized elements existing in the controlled zone (Annex II);

f) installation of lockout/tagout sign.

10.5.2 The state of de-energized installation shall be maintained until authorization for re-energization, and shall be re-energized respecting the following sequence of procedures:

a) removal of tools, fixtures, and equipment;

b) removal of all non-involved workers from the controlled zone during the re-energization process;

c) removal of temporary grounding, equipotentialization, and additional protections;

d) removal of the lockout/tagout sign;

f) unlocking, if present, and reconnection of the sectioning devices.

10.5.3 The measures listed in items 10.5.1 and 10.5.2 may be changed, replaced, expanded, or eliminated, depending on the specificities of each situation, by a legally qualified professional, authorized and with technical justification previously formalized, provided that the same level of safety originally recommended is maintained.

10.5.4 The services to be performed in disconnected electrical installations, but with the possibility of energization, by any means or reason, shall meet what is established in item 10.6.

10.6 Safety in Energized Electrical Installations

10.6.1 Interventions in electrical installations with a voltage equal to or higher than 50 volts in alternating current or higher than 120 volts in direct current can only be performed by workers who meet what is established in item 10.8 of this NR. The workers referred to in the previous item shall receive safety training for work with energized electrical installations, with the minimum content, workload, and other determinations established in Annex III of this NR. The basic operations such as connecting and disconnecting electric circuits, performed at low voltage, with electric materials and equipment in perfect working condition, suitable for operation, may be performed by any non-instructed person.

10.6.2 Work requiring entry into the controlled zone shall be carried out using specific procedures respecting the distances established in Annex II.

10.6.3 The services on or near energized installations shall be stopped immediately in the event of imminent occurrence that could put workers in danger.

10.6.4 Whenever technological innovations are implemented or new electrical installations or equipment are put into operation, risk analysis shall be conducted in advance, developed with de-energized circuits and their respective work procedures.

10.6.5 The person responsible for carrying out the service shall stop the activities when an unexpected unsafe situation or condition, whose immediate elimination or neutralization is not possible, is verified.

10.7 Work Involving High Voltage (HV)

10.7.1 Workers who work in energized electrical installations with high voltage, who carry out their activities within the limits specified as controlled and risk zones, according to Annex II, shall comply with the provisions of item 10.8 of this NR.

10.7.2 The workers mentioned in item 10.7.1 shall receive specific safety training in and near the Electric Power Systems, with minimum content, workload, and other determinations established in Annex III of this NR.

10.7.3 The services in energized electrical installations at high voltage, as well as those performed in electrical power system (EPS), cannot be performed individually.

10.7.4 All work on energized electrical installations at high voltage, and those that interact with the Electric Power Systems can only be carried out under a specific work order for the date and location, signed by a superior responsible for the area.

10.7.5 Before starting work on electrical installations at high voltage, the immediate superior and the team responsible for performing the service shall perform a preliminary assessment, study and plan the activities and actions to be developed to meet the basic technical principles and the best electrical safety techniques applicable to the service.

10.7.6 The services on energized electrical installation at high voltage can only be performed when there are specific procedures, detailed and signed by an authorized professional.

10.7.7 Intervention in energized electrical installations at high voltage within the limits specified as risk zone, as per Annex II of this NR, can only be carried out by deactivation, also known as locking out, of automatic reclosers of the circuit, system, or equipment. The deactivated equipment and devices shall be marked with identification of the deactivation condition, according to the specific standardized work procedure.

10.7.8 The equipment, tools, and devices that are insulated or equipped with insulating materials, intended for work at high voltage, shall be subjected to periodic electrical tests or laboratory tests, in accordance with the manufacturer’s specifications, the company’s procedures, and in their absence, annually.

10.7.9 Every worker involved in energized electrical installations at high voltage, as well as those engaged in activities within the Electric Power Systems, shall have equipment that allows continuous communication with other team members or the operation center during the service.

10.8 – Qualification, Training, and Authorization of Workers

10.8.1 A worker who proves completion of a specific electrical course recognized by the Official Education System is considered qualified.

10.8.2 A worker who has been previously qualified and registered with the competent professional council is considered legally qualified.

10.8.3 A worker is considered skilled if he meets the following conditions simultaneously:

a) receives training under the guidance and responsibility of a qualified and authorized professional; and

b) works under the responsibility of a qualified and authorized professional. The training shall only be valid for the company that provided it and under the conditions established by the qualified and authorized professional responsible for the training.

10.8.4 Workers who are qualified or skilled, and qualified professionals with formal consent from the company are considered authorized.

10.8.5 The company shall establish an identification system that allows knowing the scope of authorization of each worker at any time, according to item 10.8.4.

10.8.6 Workers authorized to work on electrical installations shall have this condition recorded in the company’s employee registration system.

10.8.7 Workers authorized to work on electrical installations shall undergo health examinations compatible with the activities to be performed, carried out in accordance with NR-7 and recorded in their medical records.

10.8.8 Workers authorized to work on electrical installations shall have specific training on the risks arising from the use of electrical energy and the main measures to prevent accidents in electrical installations, in accordance with Annex III of this NR. The company shall grant authorization in accordance with this NR to qualified or skilled workers and qualified professionals who have participated with a successful completion in the courses listed in Annex III of this NR. A refresher training shall be carried out biennially or whenever any of the following situations occurs:

a) change of function or change of company;

b) return from absence or inactivity from work for a period exceeding three months;

c) significant modifications to the electrical installations or change of work methods, processes, and organization. The workload and program content of refresher training aimed at meeting paragraphs (a), (b), and (c) of item shall meet the needs of the situation that justified it. Work in classified areas shall be preceded by specific training according to the risk involved.

10.8.9 Workers engaged in activities not related to electrical installations within the free zone and in the vicinity of the controlled zone, as defined in this NR, shall be formally instructed with knowledge to identify and assess their possible risks and adopt the necessary precautions.

10.9 Fire and Explosion Protection

10.9.1 Areas where there are electrical installations or equipment shall be provided with protection against fire and explosion, as provided in NR-23 (Fire Protection).

10.9.2 Materials, parts, devices, equipment, and systems intended for use in electrical installations in environments with potentially explosive atmospheres shall be evaluated for compliance under the Brazilian Certification System.

10.9.3 Processes or equipment capable of generating or accumulating static electricity shall have specific protection and electrical discharge devices.

10.9.4 In electrical installations in classified areas or areas subject to a significant risk of fire or explosion, protective devices, such as alarms and automatic disconnection devices, shall be adopted to prevent overvoltage, overcurrent, insulation failures, heating, or other abnormal operating conditions.

10.9.5 Services on electrical installations in classified areas can only be performed by means of permit to work with formal release, as established in item 10.5 or by eliminating the risk agent that determines the classification of the area.

10.10 Safety Signs

10.10.1 Adequate safety signs shall be adopted in electrical installations and services, intended for warning and identification, complying with the provisions of NR-26 (Safety Signs), to meet, among others, the following situations:

a) identification of electrical circuits;

b) locking of control devices and systems;

c) access restrictions and impediments;

d) delimitation of areas;

e) marking of circulation areas, public ways, vehicles, and cargo movement;

f) signs to prevent energization;

g) identification of locked equipment or circuit.

10.11 Work Procedures

10.11.1 Services in electrical installations shall be planned and carried out in accordance with specific and standardized work procedures, with a detailed description of each task, step by step, signed by a professional who meets the requirements of item 10.8 of this NR.

10.11.2 Services in electrical installations shall be preceded by specific work orders, approved by an authorized worker, containing, at a minimum, the type, date, location, and references to the work procedures to be adopted.

10.11.3 Work procedures shall contain, at a minimum, objective, scope, technical basis, competencies and responsibilities, general provisions, control measures, and final guidelines.

10.11.4 Work procedures, health and safety training, and authorization referred to in item 10.8 shall have the participation of the Specialized Service in Occupational Health and Safety (SESMT), if any.

10.11.5 The authorization referred to in item 10.8 shall be in accordance with the health and safety training requirements outlined in Annex III of this NR.

10.11.6 Every team shall have one of its workers appointed and capable of supervising and conducting the work.

10.11.7 Before starting work as a team, its members, together with the person responsible for performing the service, shall conduct a preliminary assessment, study and plan the activities and actions to be performed on site, to meet the basic technical principles and best safety techniques applicable to the service.

10.11.8 The rotation of activities shall consider the risk analysis of the tasks and the competence of the workers involved, to ensure health and safety at work.

10.12 Emergency Situation

10.12.1 Emergency actions involving electrical installations or services shall be included in the company’s emergency plan.

10.12.2 Authorized workers shall be able to perform rescue and first aid to the injured, especially by performing cardiopulmonary resuscitation (CPR).

10.12.3 The company shall have standardized rescue methods that are appropriate to its activities and provide the means for their application.

10.12.4 Authorized workers shall be able to use and operate fire prevention and firefighting equipment on electrical installations.

10.13 Responsibilities

10.13.1 The contracting and contracted parties are jointly and severally responsible for complying with this NR. (Repealed by SEPRT Ordinance No. 915, July 30, 2019)

10.13.2 It is the responsibility of the contracting companies to keep the workers informed about the risks they are exposed to, instructing them about the procedures and control measures to be adopted against electrical risks.

10.13.3 It is the company’s responsibility to propose and adopt preventive and corrective measures in the occurrence of accidents involving electrical installations and services.

10.13.4 It is up to the workers:

a) to take care of their own health and safety and that of others who may be affected by their actions or omissions at work;

b) to take responsibility jointly with the company for compliance with legal and regulatory provisions, including internal health and safety procedures; and

c) to communicate to the person responsible for the execution of the service the situations, immediately, the situations they consider a risk to their health and safety and to that of others.

10.14 Final Provisions

10.14.1 Workers shall stop their tasks by using their right to refuse to work, whenever they see evidence of serious and imminent risks to their health and safety or to others, immediately informing their supervisor who will take the applicable measures. (Repealed by SEPRT Ordinance No. 915, July 30, 2019)

10.14.2 Companies shall promote actions to control risks originated by others in their electrical installations and immediately report them to the competent bodies, when applicable.

10.14.3 In the occurrence of non-compliance with the provisions of this NR, the MTE shall adopt the measures established in NR-3.

10.14.4 The documentation provided for in this NR shall be permanently available to workers who work in electrical installations and services, respecting the scope, limitations, and interference in the tasks.

10.14.5 The documentation provided for in this NR shall be permanently available to the competent authorities. (Repealed by SEPRT Ordinance No. 915, July 30, 2019)

10.14.6 This NR does not apply to electrical installations powered by extra-low voltage.


Annex II – Risk Zone and Controlled Area

Annex III – Training