Electrical Safety Hazards Study Notes

Electrical Safety Hazards

Overview

  • This chapter discusses the hazards associated with electrical safety, emphasizing the need for awareness and precautionary measures.

Common Electrical Hazards

  • Static Electricity

    • Definition: Static electricity is defined as the accumulated electric charge present on an object.

    • Main Danger: The primary hazard posed by static electricity is arcing, which can ignite flammable gases or materials on contact.

  • Electric Shock

    • Awareness: It is crucial to be continuously aware of the risks associated with electric shock.

    • Key Factors: Several factors can increase the danger of electric shock:

    • Amount and path of the current

    • Type of voltage (alternating current (AC) or direct current (DC))

    • Value of the voltage

    • Duration the body is energized

    • Condition of the skin

    • Area of contact

    • Severity of Shock: When a person receives an electric shock, the current usually travels to the earth or ground through the individual. The severity of the shock correlates directly with the amount of current that passes through the body.

Current Thresholds

  • Current and Effects:

    • A current greater than 15 mA can paralyze the victim, preventing them from letting go of an energized wire.

    • Any current over 50 mA can be fatal.

Physiological Effects of Current


  • Table 1-1: Physiological Effects of Various Currents

    Current (mA)

    Effect


    1 or less

    No sensation.


    1-8

    Shock probably not felt.


    8-15

    Shock is felt but not painful; victim can let go. Muscular control is maintained.


    15-20

    Shock is painful; victim can let go. Muscular control is maintained.


    20-50

    Shock is painful; victim cannot let go. Muscular control is lost. Breathing is difficult.


    50-200

    Shock is very painful; severe muscular contractions. May cause death from ventricular fibrillation.


    Over 200

    Severe burns and muscular contractions; victim cannot breathe during shock.

    Voltage Hazards

    • The likelihood of electric shock increases proportionally with voltage.

    • Common Household Voltage: More fatalities have occurred from contact with 120 volts AC than any other voltage.

    • Dangerous DC Voltages: Industrial DC voltages as low as 42 volts can be lethal.

    • High Voltage Definition: High voltage is defined as an AC voltage higher than 750 volts.

    Resistance of Human Body

    • The electrical resistance of the human body varies due to factors such as moisture, salt, and skin abrasions.

    • Resistance Range: Human skin resistance varies from 100 Ω (ohms) to over 500,000 Ω.

    • Impact of Abrasions: Abrasions significantly reduce body resistance below 100 Ω due to the loss of the insulating properties of the skin.

    First Response to Electric Shock

    5 Steps to Rescue a Shock Victim

    1. Protect Yourself: Act fast but ensure you do not touch the energized victim to avoid also receiving a shock.

    2. Free the Victim: Remove the victim from the electrical contact by either freeing them or shutting off the power.

    3. Apply CPR: If necessary, provide cardiopulmonary resuscitation (CPR) or artificial respiration.

    4. Call for Help: Have someone contact a medical professional (doctor, nurse, fire department, police).

    5. Continue Resuscitation: Maintain resuscitation efforts until a medical authority advises you to stop.

    Grounding Principles

    • Proper grounding of tools and equipment is critical to minimizing electrical hazards.

    • Grounding Requirements: Portable tools must be adequately grounded using either:

      • Approved three-wire cords with three-prong polarized plugs, or

      • Two-prong plugs that are double insulated.

    • CSA Symbol: Look for the Canadian Standards Association (CSA) symbol on grounded tools.

    Tool Safety & Equipment

    • GFCI Requirement: Always use a ground fault circuit interrupter (GFCI) when utilizing corded power tools outside or in wet conditions.

    Lock-Out and Tagging Procedures for Electrical Equipment

    • Regulatory Framework: The following details adherence to electrical safety codes, particularly concerning maintenance procedures in workplaces:

    • Rule 2-304 - Disconnection:

      1. No repairs or alterations should be performed on live equipment unless complete disconnection is impractical.

    • Maintenance Context: Gas technicians often work where powered machinery maintenance is ongoing; thus, detailed lock-out procedures are vital to ensuring safety during maintenance.

    Lock-Out Procedure Essentials

    • Lock-out entails more than just disconnecting power; it includes ensuring all energy sources (electrical, pneumatic, hydraulic, or gravitational) are rendered inoperative—this state is referred to as “zero mechanical state.”

    • Communication: The machine operator must be informed of maintenance efforts, and locks used must clearly identify the individual responsible.

    • Lock Removal: Only the person who applied a lock is allowed to remove it; combination locks are prohibited in this context.

    Worker Responsibilities

    • Employees engaged in lock-out procedures should:

      • Lock control devices

      • Remove their locks upon completion of their work

    • Emergency Removal: Locks may only be removed by the installer or, in emergencies, by a designated supervisor after attempting to reach the lock installer to ensure safe operation.

    • Authority to Re-energize: Equipment will not be re-energized unless instructed by the worker who initiated the lock-out or a supervisor confirming safe conditions.

    Compliance with Electrical Codes

    • Individuals who carry out electrical work related to fuel-burning appliances must adhere strictly to electrical code regulations.

    • The Electrical Safety Codes prescribe specific rules for the installation and maintenance of electrical equipment concerning gas-fired systems.

    Specific Electrical Code Rules

    • Rule 2-032 - Damage and Interference: No damage or interference with electrical installations is permitted, except where necessary during non-electrical equipment repairs, and restoration to safe operating condition must occur promptly.

    • Rule 2-100 - Marking of Equipment:

      • All electrical equipment must have appropriate markings for identification and operational suitability, including:

      • Maker's name and trademark

      • Catalogue number or type

      • Voltage and rated load amperes.

    • Rule 10-406 - Non-electrical Equipment:

      • Bonding metal water piping systems to grounding conductors is required using appropriate copper bonding conductors.

    • Subrules for Heating Equipment Rated 117 kW or Less:

      • Electric power must be provided from a sole branch circuit for heating units, ensuring no other uses on this circuit.

      • Specific provisions address circulating pumps and safety disconnecting means for branch circuits associated with heating units.

    Final Thoughts

    • Proper understanding and compliance with electrical safety measures and codes are essential for minimizing risks and ensuring safety during electrical work.