Two parcels with different hazard labels cannot just ride together in the same vehicle or container. ADR 7.5.2 sets out a single rule with one table that decides what goes with what.
The default rule (7.5.2.1). Packages bearing different hazard labels must not be loaded together in the same vehicle or container — unless the table in 7.5.2.1 permits it at their intersection, either with an X or with one of the footnote symbols. The table is indexed by label number (1, 1.4, 1.5, 1.6, 2.1/2.2/2.3, 3, 4.1, 4.1+1, 4.2, 4.3, 5.1, 5.2, 5.2+1, 6.1, 6.2, 7 A/B/C, 8, 9/9A).
X means “mixed loading permitted.” An empty cell means mixed loading is prohibited — the table has no “permit” route around it. Footnotes qualify the rule — a permits mixed loading with 1.4S substances and articles, b permits Class 1 goods with Class 9 life-saving appliances (UN 2990, 3072, 3268), c covers pyrotechnic safety devices of 1.4G (UN 0503) with electrically initiated safety devices of Class 9 (UN 3268), d covers blasting explosives together with ammonium nitrate and certain nitrates.
Class 1 inside itself (7.5.2.2). Explosives in different compatibility groups have their own, stricter table (groups A, B, C, D, E, F, G, H, J, L, N, S). Don’t just trust the Class 1 column in 7.5.2.1 — sub-check 7.5.2.2.
Limited quantities with explosives (7.5.2.4). Mixed loading of dangerous goods packed in limited quantities (3.4) with explosive substances and articles of any type is prohibited, except with Division 1.4 and UN Nos. 0161 and 0499. The LQ regime is not a way around the mixed-loading rules.
Separate transport documents. If two goods cannot be loaded together, they each need their own transport document (5.4.1.4.2, NOTE 1 to 7.5.2.1). One combined waybill for a segregated load is not valid.
Common mistake — loading Class 5.1 oxidizers with Class 3 flammable liquids “because the table shows X.” Correct — but the table is for packages only. Substances in closed containers with complete sides are not counted for the mixed-loading prohibitions on one vehicle, except for the Class 1 prohibitions of 7.5.2.1 and 7.5.2.2, which apply across containers (7.5.2.3). Tank and bulk carriage is not covered by this table at all — re-check the Column 18 CV provisions when the mode shifts from packages to tank.
References — ADR 2025 7.5.2.1 (label table), 7.5.2.2 (Class 1 compatibility groups), 7.5.2.3 (goods in closed containers), 7.5.2.4 (limited quantities with explosives), 5.4.1.4.2 (separate documents).