Maybe what we're discussing are different things.
When I think "steam table," I think of a buffet counter with pans set in it. The bottoms of these pans rest in a pool of water that is kept hot - not true steam; just hot water. No circulating system, just a big tub with water and heating elements.
The elements I'm used to seeing are 240v, and are hard-wired to a control unit. The control unit usually plugs into an appropriate receptacle under the table. The supply wires are usually #8 or #6.
This places the circuits beyond what is usually protected by a GFCI.
