CSLB C-10 Electrical ContractorSafety and TestingMedium
A contractor is installing new electrical equipment in a commercial building. According to Cal/OSHA, which of the following is a primary requirement for grounding and bonding of this equipment?
- AAll non-current-carrying metal parts of equipment operating at over 50V must be bonded and grounded.
- BBonding is sufficient without grounding for double-insulated equipment.
- CThe equipment grounding conductor must always be smaller than the circuit conductors.
- DGrounding is only required for equipment operating at over 600V to ground.
Show answer & explanationAnswer & explanation
Correct answer: A. All non-current-carrying metal parts of equipment operating at over 50V must be bonded and grounded.
Cal/OSHA, aligning with the CEC/NEC, mandates that all non-current-carrying metal parts of electrical equipment, enclosures, and raceways operating at 50 volts or more to ground must be effectively bonded and connected to an equipment grounding conductor. This ensures safety by providing a low-impedance path for fault current.
Why the other options are wrong
- B. Even double-insulated equipment, while not requiring an equipment grounding conductor, still benefits from system grounding and bonding of associated metallic enclosures or raceways per code for other safety aspects.
- C. The equipment grounding conductor size is determined by the overcurrent protective device and can be equal to or larger than the circuit conductors, not always smaller.
- D. Grounding is required for equipment at 50V or more, not just over 600V.
Cal/OSHA Grounding Requirement
Cal/OSHA mandates that non-current-carrying metal parts of electrical equipment, raceways, and enclosures operating at 50 volts or more to ground must be bonded together and connected to an effective ground-fault current path.
- Applies to equipment operating at 50V or more.
- Protects against electric shock by clearing ground faults.
- Requires both bonding (connecting metal parts) and grounding (connecting to earth).
Memory trick: OSHA's Golden Rule: Ground Everything Over Fifty!