Advances in communication and monitoring technology are expected to increase the numbers of ac- cessories that will be added to the helmets of industrial workers. Unfortunately, no guidelines currently exist for the maximum weight, or weight distribution, that can be safely supported by the head and neck in these contexts. The goal of the current work is to quantify the mass and center of gravity (CG) of helmet systems (i.e., helmet plus accessories) currently worn by underground workers. To this end, a custom measurement device was created using a headform representative of a 50th percentile male. Two different helmets and six cap lamps were investigated. Each helmet had ear protection that was considered in each of four extreme positions. The maximum helmet system mass was approximately 1 kg and the CGs ranged from 56.0 mm anteriorly to -46.5 mm posteriorly relative to the headform origin. Since these existing helmet systems have not been linked to short- or long-term issues, these measures provide a preliminary, conservative definition of a safe design envelope for evaluating for future de- velopments. Further work is needed to expand the measurements to different headform sizes and helmet systems.

Relevance to industry:​ In the absence of rigorous guidelines, the mass and CG information from current systems define a safe design envelope for the development of new helmets and helmet systems.