Square D™-brand I-Line™ circuit breaker power distribution panelboards are for use on AC or DC systems. The panels, labeled cULus (compliance to UL and CSA standards certified by UL) are also Underwriters Laboratories® (UL®) Listed under File E33139. The following are suitable for use as service entrance equipment such as all main circuit breaker panelboards. I-Line circuit breaker panelboards are available as 400–1200 A main lugs only and 100–1200 A main circuit breakers. I-Line circuit breaker panelboards are designed, manufactured, and tested to comply to UL, CSA, NFPA, NEMA & W-P standards. This door lock is used with NEMA 1 I-Line Panelboards.