Seamus,
Just seeing janitorial-skinned versions of these cleaners bearing the same model # as the consumer version makes me think of all those Royal domestic vacuums with 3-wire cords.
In those cases, the commercial equivalents were the model 3-501 Prince hand vacuum (mostly Turbo Groomers for horse grooming) and uprights models 3-153, 3-154, 3-602 and 3-604. Other than the 3-501 "Turbo Groomer" I've yet to see any one of those but I know for certain they do have 3-wire cords.
~Ben