Alternativno pa se dovoli negorljiv vod za izravnavanje zraka, ki poteka med kabino in hodnikom ter je nameščen pod sanitarnimi prostori, če premer vodov ne presega 0,05 m2.
Alternatively, a non-combustible air balance duct routed between the cabin and the corridor and located below the sanitary unit is permitted where the cross-sectional area of the duct does not exceed 0,05 m2.