It is done quite frequently in industrial control electronics where the DC power common is connected to earth ground, this however is commonly done with a star ground point, and/or something called equi-potential bonding, this is ensuring that all metallic parts are bonded to avoid ground loops.
I have a PDF on this by Siemens but it is too large to upload, they used to have it on their site but unfortunately it is no longer there since they revamped the site.
M.