Guidelines for Working at Voltages < 240 Volts

February 4, 2005---DRAFT

NOTE: Working hot is a LAST ALTERNATIVE. Electrical hot work is defined as: Working on or near exposed conducting parts that are or might become energized at 50V or more. Refer to Electrical Safety Flowchart for Working On or Near Live Parts. Engineered methods to prevent exposed sources of 50V and greater are to be implemented wherever practical.

Only QUALIFIED PERSONNEL {as defined in NFPA 70E Article 110.6(D) 2004 edition} as authorized by the CAT/supervisor/division can perform such work. Refer to Qualified Electrical Worker Flow Chart.

Training requirements: ES&H 114 (LOTO) / ES&H 375 (NFPA 70E) / ES&H 371 (electrical worker) - Observe Electrical Safe Work Practices. Refer to Electrical Safe Work Practices.

Energized Electrical (Hot) Work Permit: An approved and valid Hot Work Permit is required for all hot work other than voltage verification for LOTO. Extended Duration Permits for broad scope activities such as routine troubleshooting, testing of energized equipment <240 Volts can be put in place for an extended duration (up to one year). Refer to APS Policy on Energized Electrical Work, including Test & Measurement of Energized Circuits and to APS Energized Electrical Test & Measurement Authorization form.

NOTE: In case of an emergency, circuit breakers and/or disconnect switches can be turned off (de-energized) without the requirements of PPE. (Safe work practice -- stand to the side of the device when operating.)

 

Guidelines below are intended only for qualified and authorized persons.

Clothing/PPE requirements for the following tasks (Hazard Category 0):

  • Non-metallic safety glasses
  • Natural fiber outer wear (e.g., all cotton)
  • Voltage rated gloves if working near exposed voltages. These must be voltage rated greater than the working voltage.
  • Insulated tools if working near exposed voltages. These must be voltage rated greater than the working voltage.

Tasks that can be performed at voltages <240V (assumes equipment is energized, and work is done within the flash protection boundary):

  • Operation of circuit breakers or fused switches (covers on or off)
    Hazard category - 0
    Minimal PPE required: untreated natural fiber long sleeve shirt, untreated natural fiber long pants, safety glasses.
    (Safe Practice: When operating these devices, ALWAYS stand to the side NEVER stand directly in front of the device.)
  • Opening hinged covers to expose bare, energized parts
    Hazard category - 0
    Minimal PPE required: untreated natural fiber long sleeve shirt, untreated natural fiber long pants, safety glasses
    CAUTION: Once opened, task and requirements may change.
  • Removal of bolted covers to expose bare, energized parts
    Hazard category - 1
    Minimal PPE required: FR long sleeve shirt, FR long pants, safety glasses, hard hat.
    Reduces to hazard category 0 provided that there is <10KA short circuit current available

    Hazard category - 0
    Minimal PPE required: untreated natural fiber long sleeve shirt, untreated natural fiber long pants, safety glasses.
  • Remove/install circuit breakers or fused switches
    Hazard category - 1
    Minimal PPE required: FR long sleeve shirt, FR long pants, safety glasses, hard hat, voltage rated gloves, and voltage rated tools.
    Reduces to hazard category 0 provided that there is <10KA short circuit current available

    Hazard category - 0
    Minimal PPE required: untreated natural fiber long sleeve shirt, untreated natural fiber long pants, safety glasses, voltage rated gloves, voltage rated tools.
  • Work on energized parts including voltage testing
    Hazard category - 1
    Minimal PPE required: FR long sleeve shirt, FR long pants, safety glasses, hard hat, voltage rated gloves, and voltage rated tools.
    Reduces to
    hazard category 0 provided that there is <10KA short circuit current available
    Hazard category - 0
    Minimal PPE required: untreated natural fiber long sleeve shirt, untreated natural fiber long pants, safety glasses, voltage rated gloves, voltage rated tools.
  • Voltage testing for LOTO of circuit breakers at receptacles.
    Reduces to
    hazard category 0 - provided that there is <10KA short circuit current available
    Hazard category - 0
    Minimal PPE required: untreated natural fiber long sleeve shirt, untreated natural fiber long pants, safety glasses, voltage rated tools.

    • Types of test equipment that can be used (<240V) at receptacle locations (Non-exposed)

      120V wire tester (Voltage rated greater than circuit voltage to be tested) (Three wire tester that plugs in like a line cord) No PPE required.

      120V GFCI tester (Voltage rated greater than circuit voltage to be tested) (Three wire tester that plugs in like a line cord) No PPE required.

      Inductive voltage tester (Voltage rated greater than circuit voltage to be tested) No PPE required.

      Multimeter CAT III 1000V -- Minimal PPE required: untreated natural fiber long sleeve shirt, untreated natural fiber long pants, safety glasses.

      The selection of a method of testing listed above is determined by the worker. It is the worker that must be assured that the chosen method has determined that power at the receptacle is present or not.

      Phase rotation meter <240V provided that the unit plugs into the receptacle similar to a line cord, (Voltage rated greater than circuit voltage to be tested) -- No PPE required.

Comment: In general, 480/208 transformers less than 100 KVA have a short circuit current <10KA. All Panel boards will soon be labeled with pertinent information.

CAUTION: Even though the short circuit current available is < 10KA (reduced possibility of arc flash), if an energized circuit is shorted it will still result in sparks and possible spewing of melted metal.

Information regarding V-rated gloves and fire retardant (FR rated) clothing can be obtained from Tom Barsz.