Switchboard Insulation Resistance Chart

Always use a 500 or 1,000 Vdc megohmmeter when testing insulation resistance.

NOTE: The Neutral–Ground column in the following table is provided to record the results of the pre-energizing checkout procedure only.

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462 or local equivalent. This equipment must be installed and serviced only by qualified personnel. Perform such work only after reading and understanding all of the instructions contained in this bulletin. Turn off all power supplying this equipment before working on or inside equipment. Before performing visual inspections, tests, or maintenance on this equipment, disconnect all sources of electric power. Assume all circuits are live until they are de-energized, tested, and tagged. Pay particular attention to the design of the power system. Consider all sources of power, including the possibility of backfeeding. Always use a properly rated voltage sensing device to confirm power is off. Handle this equipment carefully and install, operate, and maintain it correctly for it to function properly. Carefully inspect the work area and remove any tools and objects left inside the equipment. Replace all devices, doors, and covers before turning on power to this equipment. All instructions in this manual assume that the customer has taken these measures. Failure to follow these instructions will result in death or serious injury.

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462 or local equivalent.
This equipment must be installed and serviced only by qualified personnel.
Perform such work only after reading and understanding all of the instructions contained in this bulletin.
Turn off all power supplying this equipment before working on or inside equipment.
Before performing visual inspections, tests, or maintenance on this equipment, disconnect all sources of electric power. Assume all circuits are live until they are de-energized, tested, and tagged. Pay particular attention to the design of the power system. Consider all sources of power, including the possibility of backfeeding.
Always use a properly rated voltage sensing device to confirm power is off.
Handle this equipment carefully and install, operate, and maintain it correctly for it to function properly.
Carefully inspect the work area and remove any tools and objects left inside the equipment.
Replace all devices, doors, and covers before turning on power to this equipment.
All instructions in this manual assume that the customer has taken these measures.

Failure to follow these instructions will result in death or serious injury.

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.

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.