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Which hazard classes require placarding at any quantity?

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Correct answer

Table 1 hazards: Class 1 (Explosives 1.1-1.3), Class 2.3 (poison gas), Class 4.3 (dangerous when wet), Class 6.1 (some poison), Class 7 (some radioactive), and others

  1. A Only Class 9 miscellaneous materials
  2. B All hazard classes require placarding at any quantity
  3. C Table 1 hazards: Class 1 (Explosives 1.1-1.3), Class 2.3 (poison gas), Class 4.3 (dangerous when wet), Class 6.1 (some poison), Class 7 (some radioactive), and others
  4. D Only flammable liquids

Why this is the answer

Table 1 of the Hazardous Materials Table lists hazards so dangerous that any amount triggers full placarding requirements. These include explosives classes 1.1, 1.2, and 1.3 (mass-detonation hazards); poison gas (2.3); dangerous-when-wet (4.3); poison-by-inhalation (6.1 in some categories); and certain radioactive materials. Table 2 hazards (most of the common ones — flammable liquids, oxidizers, corrosives, non-toxic flammable gases) require placards only when the load exceeds 1,001 pounds aggregate. The distinction matters because Table 1 materials can be lethal in tiny quantities and need maximum visibility. Cargo placarded with a Table 1 hazard must also use the corresponding identification number on or near the placard.
Source: FMCSA CDL Manual 9.2.5 Placarding Tables

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About this topic: Communication Rules

Communication rules cover shipping papers, placards, labels and markings: what each must show, where papers must be kept in the cab, and when placards are required. This is the most heavily tested hazmat topic. This is one of 19 Hazardous Materials questions on communication rules, each with a full explanation on a single study page.

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