An unspliced __ that is sized based on the derived phase conductors shall be used to connect the grounded conductor and the supply-side bonding jumper, or the equipment grounding conductor, or both, at a separately derived system.
system bonding jumper
equipment grounding conductor
grounded conductor
grounding electrode conductor
The Correct Answer and Explanation is:
Correct Answer: System Bonding Jumper
Explanation:
In the context of electrical systems, especially those involving separately derived systems (SDS) such as transformers or generators, proper bonding and grounding are crucial for system safety, equipment protection, and personnel safety. The National Electrical Code (NEC) provides guidelines on how to make these connections correctly.
The system bonding jumper is a critical component in these setups.
The question refers to an unspliced conductor that connects the grounded conductor (typically the neutral) to the equipment grounding conductor (EGC) or the supply-side bonding jumper (SSBJ), or both, at a separately derived system. This role is performed by the system bonding jumper.
What is a System Bonding Jumper?
A system bonding jumper is the connection between the grounded conductor (neutral) and the equipment grounding conductor or bonding means at the source of a separately derived system, such as a transformer or generator.
According to NEC Article 250.30(A)(1):
“An unspliced system bonding jumper, sized based on the derived ungrounded conductors, shall be used to connect the grounded conductor and the supply-side bonding jumper, or the equipment grounding conductor, or both.”
This bonding jumper ensures a low-impedance path for fault current, allowing overcurrent protection devices (like breakers or fuses) to function properly in the event of a ground fault.
Why is It Important?
- Safety: It prevents the build-up of voltages on non-current-carrying metallic parts by ensuring an effective fault path.
- System Protection: Allows for quick operation of protective devices during faults.
- Code Compliance: The NEC mandates it for all separately derived systems to prevent hazardous conditions.
Common Mistake:
Some may confuse the system bonding jumper with the grounding electrode conductor (GEC) or equipment grounding conductor, but these serve different purposes:
- GEC connects the SDS to the grounding electrode (e.g., ground rod).
- EGC runs with the circuit conductors and carries fault current from the load.
- System bonding jumper connects the neutral to the EGC and/or SSBJ at the SDS.
Summary:
Thus, the correct answer is system bonding jumper, as it is the unspliced conductor used to connect the grounded conductor to the supply-side bonding jumper or equipment grounding conductor at a separately derived system.
