What is the difference between the limited and restricted approach boundaries?

The limited approach boundary is the closest an unqualified person may come without an escort. The restricted approach boundary is the closest a qualified person may come, and only with proper insulated PPE, tools, and a documented plan because of the increased risk of inadvertent contact.

Why is there no prohibited approach boundary?

NFPA 70E removed the prohibited approach boundary after the 2015 edition because it added complexity without improving safety. The restricted approach boundary is now the innermost shock-protection boundary, and direct contact with energized parts requires rated protection regardless.

Does this give the arc flash boundary too?

No. The arc flash boundary is a separate energy-based calculation tied to the incident energy reaching 1.2 cal/cm squared at the worker, which depends on available fault current and clearing time. This tool covers only the shock approach distances from Table 130.4(D)(a).

Why are there two limited approach distances?

An exposed movable conductor, such as an overhead line that can swing, requires a larger limited approach distance than a fixed circuit part that cannot move toward the worker. The table lists both so you can apply the correct one for the hazard present.

Can an unqualified worker ever cross the limited boundary?

Only when continuously escorted by a qualified person and equipped with appropriate PPE. Otherwise the limited approach boundary is the hard line an unqualified worker must stay outside of around energized equipment.

What is the Electrical Safety Clearance Distance Calculator?

Enter a nominal AC system voltage from 50 V to 800 kV and get the limited approach and restricted approach shock boundaries from NFPA 70E Table 130.4(D)(a), with guidance for qualified versus unqualified workers near energized equipment. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Electrical Safety Clearance Distance Calculator

Name: Electrical Safety Clearance Distance Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Working safely near energized equipment starts with knowing how close anyone may get. This tool returns the NFPA 70E shock-protection approach boundaries for a given AC system voltage, distinguishing what a qualified worker may cross from what an unqualified worker must stay outside of, so you can mark out a safe work zone before the job starts.

How it works

The tool matches your voltage to a band in NFPA 70E Table 130.4(D)(a) and returns three distances:

limited approach (movable conductor) → unqualified must stay outside
limited approach (fixed circuit part) → smaller, for non-swinging parts
restricted approach (qualified only)  → innermost shock boundary

The limited approach boundary is the line for unqualified personnel; crossing it requires being a qualified person or being escorted by one. The restricted approach boundary is the inner line a qualified person may cross only with rated insulated PPE, insulated tools, and a documented energized-work plan.

Understanding the two approach boundaries

NFPA 70E defines shock protection in two concentric zones:

Limited approach boundary — The outer perimeter. Unqualified workers (people who are not trained in electrical hazard recognition) must remain outside this line unless escorted by a qualified person and wearing appropriate PPE. There are two limited-approach distances because a movable conductor — such as an overhead service drop that can swing in wind — creates a larger hazard zone than a fixed busbar that stays put.

Restricted approach boundary — The inner perimeter, for qualified workers only. Crossing it requires rated insulated gloves, insulated tools, and a completed energized electrical work permit (EEWP). Contact inside this zone with an energized part causes direct shock, so the standard expectation is that qualified workers always use PPE and insulated tools when within this distance.

Voltage examples and typical distances

Nominal system voltage	Limited approach (fixed conductor)	Restricted approach
120 V	3 ft 6 in	Avoid contact
480 V	3 ft 6 in	1 ft 0 in
600 V	3 ft 6 in	1 ft 0 in
4,160 V	5 ft 0 in	1 ft 5 in
15,000 V	5 ft 0 in	2 ft 2 in

These are illustrative values from NFPA 70E Table 130.4(D)(a); always use the current adopted edition for your jurisdiction and verify against a qualified hazard assessment.

Shock vs. arc flash: they are different boundaries

The distances this tool returns are shock approach boundaries only. They govern proximity to energized conductors to prevent direct electrical contact. The arc flash boundary is entirely separate — it is a calculated distance based on incident energy (in cal/cm²) and the fault clearing time of the upstream overcurrent device, and it is frequently larger than the shock boundaries at medium-voltage or high-fault-current systems. A complete electrical safety analysis requires both: a shock hazard analysis (this tool covers that portion) and an arc flash study performed by a qualified electrical engineer using the incident energy method or the tables in NFPA 70E.

The most important principle in NFPA 70E is that the preferred option is always to de-energize and verify absence of voltage before working. Energized work is justified only when it can be shown that de-energizing would create a greater hazard or is infeasible due to equipment design.