is there a requirement to have a ground loop around a building to ensure against touch potential?
(please state rule#)
Or is this only for substations (step and touch)
If the building has voltages lower than 750 volts then no, a ground loop is not required. Section 10 grounding rules apply.
If the building has a vault with voltages exceeding 750 volts then there must be station ground electrode which follows the minimum standards in 36-302.
Most buildings with electrical vaults will have engineered grounding requirements meeting or exceeding the requirements in section 36