terminals in motors, appliances, and electronic equipment may be exposed. Older equipment may have exposed electrical parts. If you contact exposed live electrical parts, you will be shocked. You need to recognize that an exposed electrical component is a hazard.
The risk from exposed live parts depends on your distance from the parts. Three “boundaries” are key to protecting yourself from elec- tric shock and one to protect you from arc flashes or blasts. These boundaries are set by the National Fire Protection Association (NFPA 70E).
The limited approach boundary is the closest an unqualified per- son can approach, unless a qualified person accompanies you. A qualified person is someone who has received mandated training on the hazards and on the construction and operation of equipment involved in a task.
The restricted approach boundary is the closest to exposed live parts that a qualified person can go without proper PPE (such as, flame-resistant clothing) and insulated tools. When you're this close, if you move the wrong way, you or your tools could touch live parts.
Same for the next boundary:
The prohibited approach boundary—the most serious—is the dis- tance you must stay from exposed live parts to prevent flashover or arcing in air. Get any closer and it's like direct contact with a live part.
Electric Shock Boundaries To Live Parts for 300–600 Volts
Power source ➔
3 ft. 6 in.