Hazard classes that appear in the second of the two placard tables generally need placards only once the load passes a weight figure. What is that figure, and what does the exception leave untouched?

Explanation

For highway or rail movement, a transport vehicle or freight container holding less than 454 kg (1,001 pounds) aggregate gross weight of second-table materials does not have to be placarded. Two carve-outs sit in the same sentence and both matter on the road: the exception does not apply to bulk packagings, and it does not apply to materials that the subsidiary hazard placarding rule covers, which is why a small quantity of an inhalation hazard still gets placards. Note also that the weight is aggregate across the vehicle rather than per package, so amounts from separate shipping papers add up, and that being excepted does not forbid placarding anyway if a carrier chooses to. The second option strips off the carve-outs that make the rule usable, the third swaps in the figure that belongs to a different rule about when one category's own placard displaces a combined one, and the fourth denies the exception exists.

Source: 49 CFR 172.504(c)