49 CFR § 172.404 - Labels for mixed and consolidated packaging.
(a) Mixed packaging. When compatible hazardous materials having different hazard classes are packed within the same packaging, or within the same outside container or overpack as described in § 173.25, the packaging, outside container or overpack must be labeled as required for each class of hazardous material contained therein.
(b) Consolidated packaging. When two or more packages containing compatible hazardous materials are placed within the same outside container or overpack, the outside container or overpack must be labeled as required for each class of hazardous material contained therein, unless labels representative of each hazardous material in the outside container or overpack are visible.
(c) Consolidation bins used by a single motor carrier. Notwithstanding the provisions of paragraph (b) of this section, labeling of a consolidation bin is not required under the following conditions:
(1) The consolidation bin must be reusable, made of materials such as plastic, wood, or metal and must have a capacity of 64 cubic feet or less;
(2) Hazardous material packages placed in the consolidation bin must be properly labeled in accordance with this subpart;
(3) Packages must be compatible as specified in § 177.848 of this subchapter;
(4) Packages may only be placed within the consolidation bin and the bin be loaded on a motor vehicle by an employee of a single motor carrier;
(5) Packages must be secured within the consolidation bin by other packages or by other suitable means in such a manner as to prevent shifting of, or significant relative motion between, the packages that would likely compromise the integrity of any package;
(6) The consolidation bin must be clearly and legibly marked on a tag or fixed display device with an indication of each hazard class or division contained within the bin;
(7) The consolidation bin must be properly blocked and braced within the transport vehicle; and
(8) Consolidation bins may only be transported by a single motor carrier, or on railcars transporting such vehicles.