RPV

It`s a disconnect, not transfer switch. Should not have two wires ever under one lug. Front door will not open or should not when energized. Can`t tell what amperage this is by picture but I would say it`s probably 100 amp. The smaller wire is not rated for that size disconnect or breaker that feeds it and is in danger as it is on an overrated breaker. No code violation for not having lock but would never pass an electrical inspection. Obviously homeowner or friend installed with no permit or inspection.