We have everything PAT tested every couple of years. Otherwise we get things fixed when they break. We keep a couple of spare flash heads to pull in when another has to go off for repair, and a spare Nikon body in case one of the shutters goes. Repair turnaround for most equipment is pretty fast these days.
On a health and safety front I did create a safety sheet for anyone using the equipment (multiple people use the photography set ups at Fellows not just the photographers), so they could read the do's and don'ts about photographic equipment. As well as ensuring that people didn't electrocute themselves it also covered the company should someone do something silly.
Hope this helps.