I'm currently setting up a mobile workshop (aluminum fifth wheel trailer) that will require 480v 3-phase service to power welding machines. The nature of the work the mobile workshop will be used for is underwater ship repair. There will also be a transformer to supply 110/220v for lighting, air conditioning, galley, etc. The 110/220v system will be on a transfer switch that will allow me to switch from the transformer to a portable 220v generator when not connected to shore power (welding machines will not be used and 480v will not be needed for these jobs). My question is should the trailer body be bonded and grounded like a regular structure?

 

I would want the Al body to be bonded to the service entrance. You have the risk of the body becoming charged with lethal voltage and contact, inside or outside, would be a shock hazard.