Rule No. 1 (Clearance)
Enough Clearance from energized parts should be provided to avoid accidental contact with them. If that can’t be met, live parts should be guarded or enclosed.
Rule No. 2 (Minimum Height)
A minimum height from the ground to any ungrounded part of an electrical installation should be 8’-6”, so a person staying on the ground can’t touch a substation element or its part which may become energized accidentally. For example, the bottom of a post insulator supporting an energized bus does not normally have any potential.
However, if bus flashover to the ground over insulator occurs, touching the bottom of the insulator may become unsafe. That’s why an 8’-6” distance from the bottom of insulator to the ground should be provided.
Rule No. 3 (Illumination…)
There should be sufficient illumination for personnel to clearly see their surroundings and perform any work safely. Required illumination levels are specified in NESC® .
Rule No. 4 (Passage Ways…)
All passageways and stairs should be wide enough for personnel to navigate them safely, adequate railing should be provided, and floor openings should have guard rails.
Rule No. 5 (Evacuation Routes)
Exits should be clearly marked and evacuation routes should be free from obstructions. Depending on the function of the building (for example, control house), it may require several exits to avoid personnel being trapped during equipment fault, fire, etc.
Rule No. 6 (Grounding, as always)
All substation metallic structures, fences, and equipment tanks should be connected to a station ground grid which should be designed to ensure that step and touch potential values are lower than the ones stipulated in the applicable standards.