To properly ground electrical service equipment in a building, a ground connection should be made to which of the following?

In grounding electrical service equipment, the connection to the cold water line entering the building is an appropriate choice because it is typically used as a grounding electrode. The grounding system is designed to ensure safety by providing a path for electrical faults to safely dissipate into the earth. This connection helps to reduce the risk of electrical shock and fire hazards by establishing a low-resistance path for fault currents.

The cold water line is often bonded to the grounding system because it provides a reliable and conductive path to the ground. Furthermore, municipal water lines are usually buried deep enough to reach moist soil, which aids in effective grounding. This helps to ensure that any stray voltage or fault current is safely redirected.

While the other options may have roles in an electrical system, they are either not suitable for grounding purposes or do not provide the necessary low impedance path to the ground. For instance, the electrical panel is not a grounding point itself but is instead where grounding conductors may terminate or connect. Similarly, the building’s roof is not connected directly to grounding systems, and while conduits can serve as grounding paths in certain contexts, they are not typically the primary means of establishing a ground connection for the entire electrical service.