Final answer:
When exposed structural metal in a metal building frame is interconnected and not intentionally grounded or bonded, it can become energized. To prevent this, it should be considered bonded if one or more grounding electrodes are used, or if the grounding electrode conductor or bonding jumper to the grounding electrode is of sufficient size.
Step-by-step explanation:
When exposed structural metal in a metal building frame is interconnected and not intentionally grounded or bonded, it can become energized. To prevent this, it should be considered bonded if one or more grounding electrodes are used, or if the grounding electrode conductor or bonding jumper to the grounding electrode is of sufficient size. Bonding is the process of connecting the metal parts together to create a low-impedance path for electrical current to flow, effectively preventing the metal structure from becoming energized. This ensures electrical safety within the metal building frame.
Grounding is essential for the safety of an exposed structural metal building frame that is interconnected and may become energized. Proper grounding or bonding requires a sufficient size of grounding electrode conductor or bonding jumper, potentially involving multiple grounding electrodes. Safety precautions, like wearing insulated shoes, protect against electrical hazards by blocking a direct path for current through the body.
The question relates to grounding and bonding of a metal building frame in an electrical engineering context. Grounding is the process by which a conductor is connected to the earth with a good conductor so that charge can flow freely to and from Earth's unlimited reservoir. When structural metal is interconnected to form a building frame, it is imperative for safety that it is grounded or bonded properly. If not intentionally grounded or bonded, the frame is at risk of becoming energized, which could be hazardous.
In practice, exposed structural metal expected to become energized should be grounded or bonded to ensure that any charge that may accumulate is safely dissipated into the Earth, minimizing the risk of electrical shock or fire. The grounding electrode conductor or bonding jumper must be of a sufficient size to handle potential current flows, and it may involve the use of one or more grounding electrodes to establish a proper grounding system.
Moreover, the grounding ensures that there is a direct path to the ground that allows large currents to pass through the lowest resistance path without causing harm. Insulated shoes are a common safety precaution, as they prevent a pathway for electrons to flow through a person's body to the ground, a situation that could otherwise be dangerous.