250.32 Buildings or Structures Supplied by a
Feeder(s) or Branch Circuit(s)
(A) Grounding Electrode. Building(s) or structure(s) sup-
plied by feeder(s) or branch circuit(s) shall have a grounding
electrode or grounding electrode system installed in accor-
dance with Part III of Article 250. The grounding electrode
conductor(s) shall be connected in accordance with 250.32(B)
or (C). Where there is no existing grounding electrode, the
grounding electrode(s) required in 250.50 shall be installed.
Exception: A grounding electrode shall not be required
where only a single branch circuit, including a multiwire
branch circuit, supplies the building or structure and the
branch circuit includes an equipment grounding conductor
for grounding the normally non–current-carrying metal
parts of equipment.
I wonder if I should ground a welding shelter. The shelter is like a roofed structure on four columns. It doesn't have any walls. In the center of the shelter is the welding receptacles mounted on a unistrut.