52. Static electricity: In areas or rooms containing flammable vapours or gases, the following rules must be complied with:(1) any metallic equipment and machine must be bonded together and commonly grounded or be grounded separately to a grounding network with equivalent conductivity so as to prevent the accumulation of static electricity; and
(2) any non-metallic equipment and machine must be built and installed to first limit the accumulation of static electricity under a safety threshold and then to prevent such an accumulation in excess of the safety threshold.