What is the minimum size of copper wire permitted as a main bonding jumper in a 200-A main breaker panelboard?

The minimum size of copper wire permitted as a main bonding jumper in a 200-A main breaker panelboard is 4 AWG. This requirement ensures adequate conductivity and safety when establishing a reliable electrical connection between the grounded system and the grounding electrode conductor.

In the context of electrical systems, bonding is essential for reducing voltage differences that could lead to shock hazards or equipment damage. The National Electrical Code (NEC) outlines specific wire sizes based on the ampacity and application to ensure that the bonding jumper can handle fault currents without overheating or failing.

Using a bonding jumper of at least 4 AWG copper helps to meet these standards effectively within a 200-A panel setting. This ensures not only compliance with safety regulations but also optimizes the integrity of electrical systems, which is critical for both performance and safety. While other sizes like 2 AWG might also be viable, they exceed the minimum requirement stipulated for this scenario.