What is the prima facie duty of operators of plants with motor control centres drawing 600 volts at lethal amperages?

Operators of plants with motor control centres drawing 600 volts at lethal amperages would, on an objective assessment, reasonably foresee risks of malfunctions in the motor control centre causing death or serious personal injury. In this case and in most, the persons who would be exposed to the danger would be those required to enter the motor control centre, employees and independent contractors such as cleaners and electricians. The relationship of employer and worker would suggest policies in favour of duty rather than against. Thus, a prima facie duty is established. I see no policy considerations extraneous to the relationship as would reduce or negate the prima facie duty. In particular, this is the kind of activity for which public authorities are ordinarily liable and the foreseen risk is personal injury rather than pure economic loss. If it is true that negligence law will now develop incrementally by analogy, the analogy would be supplied by the kinds of cases where liability was imposed, long before Donoghue v. Stevenson, upon suppliers of electricity.