It’s easy to get lazy and decide to hop up in your aerial device (bucket) without a harness; it’s also very stupid. Any number of things can happen while in the air and that harness can end up being the only thing between you and a broken back. Make sure your harness fits you. Yes, they have adjustable straps, but they also have sizes. You ever seen a tiny guy with a large harness? There are 3 feet worth of straps dangling at his feet. Not all companies will require this, but they should: get an FR harness. You REALLY don’t want a harness melting on you after an arc flash.