Restricted Approach Boundary Calculator

A Restricted Approach Boundary Calculator compares an entered project distance with a recorded reference distance for a restricted boundary record. The result is the difference between the two distances after both values are converted to inches.

For the recorded example, the calculator returns an Entered distance of 18 in, a Reference distance of 12 in, and a Distance difference of 6 in. The entered record is therefore 6 in greater than the recorded reference distance.

This calculation supports approach-boundary worksheet review and documentation checks where project records contain a stated distance. It does not establish an approach boundary, authorize entry, determine shock protection requirements, or establish whether a worker is qualified.

Recorded Boundary Inputs

The calculation uses the following worksheet fields:

Field	Example	Electrical record purpose
Method and version	worksheet-v1	Identifies the recorded worksheet method and version.
Voltage basis	Line to line	Records the voltage basis associated with the source documentation.
Nominal voltage (V)	480	Records the nominal system voltage from the project record.
Recorded reference distance (entered unit)	12	Provides the comparison baseline.
Reference unit	in	Defines the unit used for the recorded reference distance.
Entered distance (entered unit)	18	Provides the project-record distance being compared.
Entered unit	in	Defines the unit used for the entered distance.
Qualified-person record	Recorded	Records whether source documentation includes this field.
Source reference	record-c	Identifies the supporting source record.

Voltage basis and Nominal voltage (V) are retained as electrical record context. In this mode, they do not change the subtraction result. The calculation compares the two recorded distances only.

Distance Difference Formula

The worksheet converts both distance values to inches, then subtracts the recorded reference distance from the entered distance:

\(\displaystyle \text{Distance difference} = \text{Entered distance in inches} - \text{Reference distance in inches}\)

For the example:

\(\displaystyle 18\text{ in} - 12\text{ in} = 6\text{ in}\)

Result	Value
Mode boundary type	restricted
Reference distance	12 in
Entered distance	18 in
Distance difference	6 in
Source note	Source recorded
Record note	Entered values comparable

A positive result means the Entered distance is greater than the Reference distance. A negative result means the entered value is less than the reference value. A zero result means both recorded distances are equal after unit conversion.

Calculation Example

The source record identifies a restricted boundary comparison with these entries:

• Method and version: worksheet-v1
• Voltage basis: Line to line
• Nominal voltage (V): 480
• Recorded reference distance (entered unit): 12
• Reference unit: in
• Entered distance (entered unit): 18
• Entered unit: in
• Qualified-person record: Recorded
• Source reference: record-c

Both distances are already expressed in inches:

\(\displaystyle \text{Reference distance} = 12\text{ in}\)

\(\displaystyle \text{Entered distance} = 18\text{ in}\)

\(\displaystyle \text{Distance difference} = 18 - 12 = 6\text{ in}\)

The result is 6 in. The record therefore shows an entered project distance that is 6 in greater than the recorded reference distance.

Record Comparison Limits

This mode is a comparison-only calculation. It converts the two recorded distances to inches and reports their arithmetic difference.

The result does not:

• Determine the required restricted approach boundary for the nominal voltage.
• Confirm that a selected distance is acceptable for the equipment or work condition.
• Permit entry into any boundary.
• Determine whether a person is qualified.
• Evaluate energized-work justification, work controls, PPE, equipment condition, or job briefing requirements.
• Resolve a mismatch between the source record and field conditions.

Use the reported Distance difference to identify and document whether project-entered information matches or differs from the referenced record. The actual boundary, personnel qualification, work authorization, and compliance decision require verification against the applicable electrical safety program, current source documentation, equipment conditions, and AHJ or employer requirements.