The earthing of intrinsically safe barriers on offshore transportable equipment

The author has been involved during the last two years in the compliance of an offshore coiled-tubing unit which required certification to hazardous-area product standards and installation-standard compliance. As part of this work there was a need to investigate in greater depth the usage of zener barrier on board offshore transportable equipment. The question of earthing zener barriers offshore is reviewed and analysed from various sources - zener barrier manufacturers, international publications, standards and technical papers. This paper explains the difficulty of proper zener barrier earthing on board offshore transportable equipment. It proposes an engineering methodology to solve this issue, When zener barriers are still required, a solution is proposed for their eat-thing and the installation is studied with a hazard analysis and risk control (HARC) approach.