Your dispatcher offers you four possible loads for tomorrow. Which of these loads requires your carrier to hold a Hazardous Materials Safety Permit (HMSP)?

49 CFR 385.403

Most hazmat loads, including everyday fuel and chemical shipments, never require an HMSP, so it's easy to assume no load does. But the bulk-explosives threshold for the highest-hazard divisions (1.1, 1.2, 1.3) is surprisingly low, just 55 pounds net weight, so even a modest-looking explosives load can legally require a federal safety permit before it moves. Knowing that 55-lb line is what lets a driver catch a dispatcher's mistake before it becomes a violation.