Typical in the electrical cabinet of process equipment. There was usually a plexiglass enclosure around the high voltage components so if someone was working inside the energized panel they couldn't bump or short with a tool across the high voltage. It actually seems like a good idea. I have seen people working on the backside of their circuit breaker panels (12 V side) without shutting off the 110 or disconnecting the shorepower cord. They weren't planning on touching the 110 V exposed terminals. I guess the insurance company is trying to minimize their liability. If the system is inherently safe then ask for a reduction in premiums.