CraigJ 
When the table is grounded into your electrical wiring, you can damage your equipment in the shop if you forget to attach the ground clamp to the table. I had a metal work light during on my weld table that had a chassis ground, and I forgot the ground clamp and it toasted the light and some cfl bulbs that were on the same circuit. Regular equipment just isn't built to handle the hf start, or low voltage amperage of a welders work circuit.
