Electricity

Contact with live electrical conductors is a serious risk because a proportion of the current passing through the human body may also pass through the heart. The current through the heart can disrupt the heart’s operation by forcing it into fibrillation, which then stops blood being pumped around the body.

IT’S THE LAW!

Under clause 41 of the NSW Occupational Health and Safety Regulation 2001 it states that the controller of the premises must ensure that any electrical installation at the premises:

(i) Is safe at the time it is made available for use by an employer, or

(ii) If not safe, is disconnected from the electricity supply and secured and the employer is informed that it is not safe.

HOW CAN ELECTRICITY AFFECT HEALTH AND SAFETY

When the body or the brain no longer receives oxygen from the blood, it begins to die. This means that contact with live parts at any voltage that causes sufficient current to pass through the heart is potentially injurious or even fatal.

Contact with live electrical components can also cause serious burns arising from the discharge of electrical energy. Health effects can include muscle spasm, shock, burns, palpitations, nausea and vomiting, collapse, fibrillation, unconsciousness, or death. Other risks include fires and explosions.

CONTROL MEASURES FOR ALL ELECTRICAL WORK

Electrical safety is primarily dependent upon appropriate job planning and correct testing procedures and techniques.

The first aim always should be to eliminate the hazard. Usually, the simplest way is to ensure the electricity supply is isolated. However, electrical equipment should not be assumed to be de-energised after isolation. Testing must be done prior to touching. Workers must be appropriately trained and competent in test procedures and in the use of testing equipment.

EXAMPLES OF WORK INVOLVING COMMON HAZARDS

HAZARD WORK ACTIVITY

Voltage between phases

  • Working on polyphase installation or systems.
  • Wiring / testing / servicing of switchboards / motors/ heaters/ controllers.
  • Working on exposed busbars/catenary wires etc.

Voltage between phases and earth

  • Working on single phase & polyphase systems.
  • Wiring/testing/servicing of switchboards / motors / heaters / controllers.
  • Working on exposed busbars/catenary wires etc.
  • General electrical work.

Voltage across undischarged capacitors

  • Work with apparently isolated plant with reactive storage components.

Multiple supply sources

  • Working in large installations or systems with standby power systems, multiple distribution boards, where source of power in a single location or zone is uncertain, such as solar energy sources.

Electrical testing in hazardous locations

  • Electrical testing in confined area with explosive gas mixture, fumes, vapour or dust which is inadequately ventilated.

Damp working conditions

  • Working in situations where condensation, spillage, drainage or seepage occurs and results in wet surroundings.

WHAT ARE LOW VOLTAGE INSTALLATIONS OR SYSTEMS

Low voltage installations or systems include any and all electrically operated circuits, apparatus, components and networks in which the electrical voltage is at or below 1000Volts a.c., or 1500Volts d.c., and this includes extra low voltage.

Many electrical occupations and tasks expose employees to low voltage electricity, such as:

  • New electrical installations or systems and their connection to supply;
  • Existing installations or systems and their maintenance and modification;
  • Temporary wiring arrangements;
  • Fault-finding on circuits or equipment;
  • Switching operations; and
  • Inspections.

Common hazards of working on or near low voltage installations or systems

Below are examples of typical sources of hazard that, individually or in combination, could lead to electric shock or severe injury. The list is not in order of priority

(a) Voltages between phases.

(b) Voltages between phases and earth.

(c) Voltages between live exposed conductors and surrounding metal framework.

(d) Voltages across undischarged capacitors.

(e) Voltages on disconnected conductors – particularly neutrals.

(f) Multiple supply sources (more than one source of supply or live circuit may be available on the premises).

(g) Voltages between live exposed conductors and the surrounding environment (including metalwork, damp situations, other conductive surfaces and persons nearby).

(h) Electrical testing or operating equipment with open enclosures in hazardous areas (as defined by AS/NZS 3000:2000).

(i) Lower voltages – for example ELV (extra low voltage) may be hazardous in a cramped situation with dampness, heat or water on the floor, especially when the worker is lying on the floor.

(j) In installations or systems where the MEN (multiple earthed neutral) system is used, the rise in the earth potential in an installation due to a high impedance return path to the distribution neutral.

(k) Damp conditions.

(l) Switched off circuits becoming live.

(m) Induced voltages.

COMMON NON-ELECTRICAL HAZARDS ENCOUNTERED IN ELECTRICAL WORK

Other hazards that may contribute to risks while carrying out electrical work include:

  • Confined spaces (where there may be a hazardous atmosphere – see below);
  • Lack of sufficient light to work safely;
  • Lack of ventilation leading to uncomfortable, hot and humid working conditions;
  • Excessive fatigue, due to pressure of deadlines or other factors;
  • Obstacles to getting the equipment switched off;
  • Using a gas flame near exposed electrical conductors (a flame is a conductor);
  • Temperature rise as a result of combustion;
  • Fall from heights;
  • Cramped working conditions;
  • Explosive atmospheres;
  • Static from clothing made from wool, wool blends, nylons and polyvinyl (unless treated with an antistatic process);
  • Electric tools and equipment (e.g. hand lamps, drills, saws, torches and test instruments);
  • Personal effects (e.g. rings, jewellery, cigarette lighters, matches, hearing aids, mobile phones and pagers, transistor radios and similar);
  • General work activities (e.g. welding, cutting, brazing, using hand saws, drilling of all types, hammering and chiselling);
  • Static from the rubbing (friction effects) of plastics;
  • Hot metal surfaces due to drilling, grinding welding, etc;
  • Use of metallic tape measures;
  • Excavation associated with electrical work; and
  • Molten metal from arcs.

Examples of confined spaces are:

  • Storage tanks, process vessels, boilers, pressure vessels, silos, and other tank like compartments;
  • Open topped spaces such as pits and degreasers; and
  • Pipes, sewers, shafts, ducts, and similar structures.

IDENTIFYING INDIVIDUAL NEEDS

When considering the risk, any one of the following factors trigger special consideration of individual worker’s needs:

  • Is the person physically fit for a task involving exposure to low voltage electricity (e.g. are they able to climb to heights to work on an overhead conductor)?
  • Does the worker have a visual deficiency (e.g. do they have a visual colour deficiency)?
  • Do they suffer from any heart, circulatory or other diseases (e.g. do they have a pacemaker)?
  • Are they taking any medication, which may increase their vulnerability to work in electrical environments (e.g. – Are the staff working excessively long hours?
  • Are they experienced in, and have they been properly
  • Do they suffer from claustrophobia?

CONTROL MEASURES FOR ALL ELECTRICAL WORK

Electrical safety is primarily dependent upon appropriate job planning and correct testing procedures and techniques.

The first aim always should be to eliminate the hazard. Usually, the simplest way is to ensure the electricity supply is isolated. However, electrical equipment should not be assumed to be de energised after isolation. Testing must be done prior to touching. Workers must be appropriately trained and competent in test procedures and in the use of testing equipment.

Elimination

Eliminate the risk of shock or burns by:

(a) Switching off the supply;

(b) Isolating the supply;

(c) Taking precautions to ensure that the supply remains isolated by locking-off and/or tagging, or by disconnecting the load side of the isolator and tying back disconnected conductors;

(d) Proving the supply is de-energised by using an approved testing instrument.

Use of personal protective equipment (PPE)

Frequently personal protective equipment (PPE) is necessary, such as:

(a) A safety helmet with face shield (as appropriate);

(b) Safety glasses/face shields (anti-flash);

(c) Safety boots;

(d) Protective clothing;

(e) Approved insulating gloves;

(f) Approved insulated tools; and

(g) Approved insulating sheeting.

Workers must be trained to be competent in the use of PPE. All the above practices should be described in the employer’s or your own (if self-employed) safe working procedures, and rigorously carried out.

Control measures to be taken before working live in emergencies

The OHS Regulation (clause 207) specifies the following precautions Working live procedures can be implemented in emergencies only:

(a) When the risks of de-energising are greater;

(b) After a written risk assessment has been completed;

(d) After determining how it can be done safely; and

(e) When authorisation has been obtained from the person in control of the premises.

ADVICE TO WORKERS

WORK SAFELY

ISOLATE THE SUPPLY

SECURE LOCKOUT DEVICE AND TAG

PROVE IT IS DE-ENERGISED

BEFORE WORKING LIVE — STOP! !

IS IT AN EMERGENCY SITUATION?

HAVE YOU DONE A RISK ASSESSMENT?

HAVE YOU BEEN AUTHORISED BY YOUR EMPLOYER?

TEST BEFORE YOU TOUCH

NEVER ASSUME IT IS DEAD

OTHERWISE YOU MAY BE!

ELECTRICAL TESTING

It is often necessary for testing to be carried out live, such as testing meters, voltage, load, and phasing. The OHS Regulation requires employers to ensure that persons conducting tests for electrical system integrity and operability, conduct the tests in a safe manner using a safe system of work, appropriate PPE and appropriate test equipment.

TAGGING OFF PROCEDURES:

Preparation for work on de-energised equipment

Do not assume that electrical equipment is de-energised after isolation. Testing must be done prior to touching. Workers must be appropriately trained and competent in the test procedures and in the use of testing equipment.

Identification

It is necessary to clearly identify the electrical equipment to be worked on and the appropriate point of supply. Identification should include labelling that is both consistent and clear at the equipment to be worked on and at all points of possible isolation, for example at the control isolator and main point of supply.

Isolation

The electrical equipment to be worked on must be isolated from all sources of supply. Where isolation is effected at a removable or rack-out circuit-breaker or combined fuse switch, it must be racked out or removed to provide a visible break for isolation verification, then locked open and danger tagged. When returning after being absent from the immediate work area, it is imperative that checks and tests are carried out to ensure that the electrical equipment being worked on is still isolated when you return, to safeguard against inadvertent reconnection by another person.

Tagging

Where practicable, appropriate tags should be placed at all points of switching.

Where appropriate, the tags should be signed and dated by all personnel involved in the work, or by the supervisor in charge of the work party. Tags should only be removed with the permission of all the signatories to the tags or, if this is not possible, by the signatories’ immediate supervisor. Identification labels should also include warnings for any abnormal hazards, for example, multiple points of supply.

Cutting Cables

When carrying out work that involves cutting existing cables, the cable must be treated as live and the procedures for working on live electrical equipment adhered to, until positive tests can be made at the point where the cable is to be cut that prove the cable is de-energised.

EMPLOYEE PREVENTIVE ACTIONS CHECKLISTS

For a copy of electrical employees preventative checklists download the Word document version of this Fact Sheet by clicking on the link below.

More info:
Download the Electricity Fact Sheet

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