Which of the following is an unacceptable method for connecting grounding conductors and bonding jumpers?

The choice of endothermic weld as an unacceptable method for connecting grounding conductors and bonding jumpers is based on the fundamental principles of grounding and bonding in electrical systems. Grounding is essential for ensuring safety and reliability in fire alarm systems.

Endothermic welding involves a chemical reaction that absorbs heat and is typically used in specific applications for permanent connections. However, it is not a suitable method for establishing electrical connections where conductivity, reliability, and longevity are critical, such as in grounding and bonding. This method carries a risk of failure due to poor conductivity over time, potentially leading to electrical faults or unsafe conditions.

In contrast, methods such as exothermic welding, which uses an intense heat-generating chemical reaction to fuse conductors, are highly effective for grounding applications. Pressure connectors and clamps, when listed and approved for use, also provide reliable connections, ensuring compliance with industry standards and regulations. These acceptable methods emphasize the importance of using techniques that guarantee the integrity of connections within an electrical system.

By understanding the criteria for acceptable grounding and bonding methods, it becomes evident that using endothermic welds can compromise system performance and safety, hence its classification as unacceptable.