A few interesting facts regarding NEC 240.87 (and a rumor!)
- An easy mistake I hear often from engineers is that arc flash mitigation is required on 1200A frame or greater. FACT: You can use 1200A frames with smaller sensors if your trip is for example 900A and a 1200A frame is required. Use a 1000A sensor and viola! NEC 240.87 no longer applies.
- As mentioned in the previous bullet, NEC 240.87 applies to circuit breakers with a sensor at 1200A or greater. It is rumored that NEC 2023 will likely have an amendment lowering this requirement to 1000A or possibly even 800A. Never hurts to keep this in mind for your future large projects!