What are approach boundaries?
Shock protection guidance (e.g. NFPA 70E-style tables) defines limited and restricted approach boundaries around exposed energised parts. Distances grow with system voltage and differ for AC vs DC.
This tool returns indicative distances from simplified voltage bands for planning and toolbox talks. Always use the edition and tables adopted by your employer, and a qualified electrical person for work planning.
Electrical Approach Boundary Calculator
Electrical · limited & restricted approach
Look up indicative shock approach distances by voltage for AC or DC exposed parts. Not a substitute for the tables in your adopted standard edition.
Formula: Boundary distances from voltage range tables (limited / restricted approach)
- Distances assume exposed energised conductors or circuit parts.
- Unqualified persons typically need escort inside the limited approach.
- Use the arc flash calculator for incident-energy PPE planning.
Frequently asked questions
Is this the arc-flash boundary?
No. Arc-flash boundary depends on incident energy. Use the arc flash calculator for PPE category / IE planning.
Exposed vs enclosed?
Approach boundaries apply when parts are exposed or when covers are removed. Closed equipment follows different rules.
Metric or imperial?
Results show both metres and feet/inches approximations for field use.
Can unqualified persons cross the limited boundary?
Typically only under escort of a qualified person, per your electrical safety programme — check local rules.
