Where a surge arrester grounding electrode conductor is installed in a ferrous metal conduit for physical protection, the installation must be in accordance with ? .
a. 250.54
b. 250.64(E)
c. 250.122
d. 250.166
The correct answer and explanation is:
The correct answer is b. 250.64(E).
Explanation:
The grounding electrode conductor (GEC) for a surge arrester plays a critical role in ensuring electrical safety by providing a path to the ground in the event of a surge or lightning strike. The installation of the GEC in a ferrous metal conduit is a common method for physical protection of the conductor, ensuring that it is shielded from physical damage. When this installation method is used, it must comply with specific requirements laid out in the National Electrical Code (NEC).
Section 250.64(E) of the NEC specifically addresses the installation of grounding conductors within ferrous metal conduit. According to this code, if the conduit is ferrous (iron-based) and is used to protect the grounding electrode conductor, the conductor must be installed in a manner that maintains its continuous integrity. This ensures that the conductor remains effectively grounded in case of a fault or surge event.
The goal of this requirement is to minimize the risk of damage to the grounding system, especially during power surges, which can be especially damaging to electrical infrastructure. By ensuring the grounding conductor is both protected and properly grounded, the safety of the electrical system is greatly enhanced, minimizing the risks of shock, fire, and damage to equipment.
Other sections like 250.54 (relating to bonding for grounding electrode conductors), 250.122 (relating to sizing of equipment grounding conductors), and 250.166 (relating to the size of grounding electrode conductors based on the service entrance size) are not applicable to the specific installation scenario of a surge arrester in a ferrous metal conduit. Thus, 250.64(E) is the correct reference for this installation.