JYT1078000

Adverse Circumstances

This section includes, but is not limited to, all electrical components of the switchboard.

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH
  • Turn off all power supplying the switchboard before cleaning.
  • Always use a properly rated voltage sensing device to confirm all power is off.
  • Before energizing the switchboard, all unused circuit breaker mounting spaces must be filled.
Failure to follow these instructions will result in death or serious injury.
NOTE: Before attempting to re-energize the switchboard following adverse circumstances, contact Schneider Electric Services at 1-888-778-2733 (US) for special instructions.

Inspection Following a Short Circuit

If a short circuit occurs, make a thorough inspection of the entire system, and verify that no damage to conductors or insulation has occurred. High mechanical and thermal stresses developed by short-circuit currents can damage conductors and insulation. Check the overcurrent-protection device that interrupted the short-circuit current for possible arcing damage.

Do not open sealed devices, such as molded case circuit breakers. Replace these devices if they are damaged. Before energizing the switchboard, all unused circuit breaker mounting spaces must be filled. For more information about these devices, refer to the appropriate instruction manual listed in Reference Publications.

Clean-up Following a Short Circuit

The insulating properties of some organic insulating materials can deteriorate during an electrical arc. If so:

  1. Remove any soot or debris.
  2. Replace carbon-tracked insulation.

Water-Soaked Switchboards

Do not clean or repair a switchboard that has been exposed to large volumes of water or submerged at any time. Current-carrying parts, insulation systems, and electrical components may be damaged beyond repair. Do not energize the switchboard. Contact Schneider Electric Services at 1-888-778-2733 (US).

Water-Sprayed or Splashed Switchboards (Clean Water Only)

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH
Turn off all power supplying this equipment before working on it.
Failure to follow these instructions will result in death or serious injury.

If the switchboard has been sprayed or splashed with small amounts of clean water, make a thorough inspection of the entire system, and verify that no damage to conductors or insulation has occurred. Do not open sealed devices such as molded case circuit breakers or fuses. Replace these devices if they are damaged. For more information about these devices, refer to the appropriate instruction manual listed in Reference Publications.

Inspection and Clean-up of Clean Water Sprayed or Splashed Switchboards

Follow steps 1–10 only if:

  • No signs of physical damage to the equipment are present.
  • The switchboard has not been submerged or exposed to water for long periods of time.
  • The water that has been in contact with the switchboard has not been contaminated with sewage, chemicals, or other substances that can negatively affect the integrity of the electrical equipment.
  • The water that has been in contact with the switchboard has not entered any area of the enclosure that may contain wiring installed as intended and located above any live part. Specifically, inspect for water entering through conduits located above live parts.

If any one or more of these conditions have not been met, contact Schneider Electric Services at 1-888-778-2733 (US).

If ALL of the conditions listed have been met, proceed as follows:

  1. Turn off all power supplying this equipment before working on or inside 
the equipment.
  2. Always use a properly rated voltage sensing device to confirm all power is off.
  3. Disconnect and electrically isolate the switchboard so that no contact can be made with energized parts.
  4. Wipe off all moisture from the bus bars, insulators, and insulating material 
with a clean, dry, lint-free cloth. Do not use cleaning agents or water displacement sprays.
  5. Prepare the switchboard for insulation resistance (Megger®) testing by disconnecting all line side supply connections and all load side cable connections to isolate the switchboard from the wiring system.
    CAUTION
    HAZARD OF OVERVOLTAGE TO CONTROL AND PROTECTION COMPONENTS
    • Remove the long-time rating plug before electrical insulation testing a circuit breaker that has a label stating “Warning: Disconnect Plug Before Dielectric Test.”
    • Some MicroLogic trip units are not rated for voltages that would occur during electrical resistance insulation testing.
    • Open all control and metering disconnects from the control circuits.
    Failure to follow these instructions can result in personal injury or equipment damage.
  6. Turn all circuit breakers or switches to their ON position. The switchboard must remain de-energized.
  7. Use a megohmmeter with a capacity of 500–1,000 Vdc and apply voltage from:
    1. Each phase-to-ground with circuit breaker on.
    2. Phase-to-phase with circuit breaker on.
  8. Record resistance values. Refer to “Switchboard Insulation Resistance Chart”.
  9. If resistance measurements are less than 0.5 megohm, call Schneider Electric Services at 1-888-778-2733 (US) for recommendations.
  10. If resistance measurements are greater than 0.5 megohm, the equipment can be energized using the procedures listed in “Energizing the Switchboard”.
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