The Square D AMP MAIN BREAKER I-LINE PANELBOARD 480Y/277 VAC 3∅ 4W 74 CIRCUIT is a circuit protection device from Square D. It safeguards wiring and connected equipment by opening or isolating the circuit when current exceeds its rated threshold. Key specifications noted on this listing include 277 VAC, 400 AMP. It is commonly in equipment protection and branch-circuit wiring applications.
