Does this calculate incident energy?

No. It calculates a relative pre-screening index from entered values and does not replace an arc-flash study.

What does study referral mean?

It means at least one user-defined triage threshold was exceeded and the row should be reviewed with a competent arc-flash study basis.

Where should fault current come from?

Use the project fault-current source for the equipment location, such as a study, measured basis or upstream calculation record.

Why include working distance?

The relative index increases when the same current-time product is considered at a shorter entered working distance.

No. PPE selection and task controls remain outside this calculator.

Arc flash pre-screening calculator

working_distance_m = working_distance_mm / 1000; fault_current_time_product_kA_s = fault_current_kA x clearing_time_s; screening_index = fault_current_time_product_kA_s / working_distance_m; threshold_margin = entered_threshold - screening_index; index_utilisation_percent = screening_index / entered_threshold x 100

The screening index is relative and user-threshold based.
The calculator does not calculate incident energy.
Fault current, clearing time, working distance and thresholds are entered by the user.
Study referral means the row should move to competent arc-flash review.

Formula variables
Variable	Meaning	Unit	Use
Ifault	Prospective fault current	kA	Entered project fault-current basis.
tclear	Clearing time	s	Entered protection clearing-time basis.
Dmm	Working distance	mm	Entered working distance.
Dm	Working distance	m	Working distance converted to metres.
IkAt	Fault current-time product	kA.s	Fault current times clearing time.
Sindex	Screening index	kA.s/m	Fault current-time product divided by working distance.
Slimit	Entered screening threshold	kA.s/m	User-entered review threshold.
Smargin	Threshold margin	kA.s/m	Entered threshold minus screening index.
Uindex	Index utilisation	%	Screening index divided by entered threshold times 100.

Arc flash pre-screening calculator technical guide

User-defined triage worksheet for Australian arc-flash records using entered fault current, clearing time, working distance and thresholds.

Arc flash pre-screening calculator technical guide

Use this calculator when a protection record needs a user-defined triage worksheet before formal arc-flash review. It combines entered prospective fault current, clearing time and working distance into a relative screening index, then compares that index with a user-entered threshold.

The result is narrow and internal to the entered worksheet criteria. It does not calculate incident energy, select PPE, interpret device curves, apply a recognised incident-energy method or set a work method. It helps keep a high-current or slow-clearing combination visible before the record is carried into work planning.

Field Use Cases

Arc flash pre-screening use cases
Work setting	Useful input	Output to record
Switchboard review	Fault current, clearing time and working distance.	Relative index and review handoff state.
Protection setting change	Revised clearing time from a protection record.	Whether the longer time exceeds the entered triage threshold.
Working-distance check	Shorter entered working distance.	Higher index for the same current-time product.
Work package planning	Entered threshold from a project review basis.	User-defined triage record for competent review.

A useful pre-screen names the source of the fault current and clearing time. A weak pre-screen hides those values and leaves the next reviewer guessing whether the row belongs to the same board, device or operating condition.

Input Basis

Input responsibility matrix
Input	Calculator treatment	Outside the calculator
Prospective fault current	Multiplied by clearing time.	Source study, measurement basis or upstream calculation.
Clearing time	Multiplied by fault current and compared with the entered time threshold.	Device curve interpretation and protection setting source.
Working distance	Converts the current-time product into a relative distance-based index.	Task posture, enclosure geometry and work method.
Screening threshold	Used as the user-entered comparison point.	Project procedure and competent study basis.

Every input is a user-entered assumption. The calculator does not verify whether the same fault-current and clearing-time values apply to the same equipment location.

Review Workflow

Enter the switchboard, device or work package reference.
Enter the prospective fault current for the equipment location.
Enter the clearing time that belongs to the same protection point.
Enter the working distance used for the pre-screen.
Enter the screening index threshold and clearing-time review threshold.
Review the threshold margin, index utilisation and review handoff state.
Keep the exported record with the source values and review basis.

This workflow keeps the worksheet out of final arc-flash study territory. It is a user-defined triage worksheet, not a study result.

Worked Australian Examples

Arc flash pre-screening examples
Situation	Inputs	Output reading	Practical note
Switchboard pre-screen	8 kA, 0.08 s and 450 mm.	1.422 kA.s/m, below a 2.5 kA.s/m threshold.	Keep the source values with the record.
Study referral	20 kA, 0.2 s and 450 mm.	8.889 kA.s/m and clearing-time review.	Move the row to competent arc-flash review.
Working-distance sensitivity	10 kA, 0.1 s and 300 mm.	Shorter distance increases the index.	Check whether the entered distance matches the task basis.

The examples use Australian protection language and metric distance. They are not incident-energy calculations.

Pre-screening Boundary

This calculator only compares entered values. It does not model enclosure geometry, conductor gap, equipment class, electrode configuration, device curve behaviour, task posture, PPE, switching method or detailed study inputs.

Study referral is intentionally broad. It means the entered user-defined triage threshold was exceeded and the row should not be treated as a simple worksheet row until the project basis, protection data and task controls have been reviewed.

Boundary With Related Calculators

Use the short-circuit current calculator when the missing value is prospective fault current. Use fuse let-through comparison when an energy value is being compared with a withstand limit. Use breaker rating comparison when protective-device rating and breaking-capacity values need a separate entered comparison. Use the testing record fields table, fault-current relationship chart and manufacturer-data guide to keep the non-calculator review context visible.

Route boundary matrix
Task	Use this page?	Better route when not this page
Record user-defined arc-flash triage values from entered current, time and distance.	Yes.	Not applicable.
Estimate prospective fault current.	No.	Short-circuit current calculator.
Compare entered device energy with a withstand limit.	No.	Fuse let-through comparison calculator.
Compare breaker rating and fault duty.	No.	Breaker rating comparison calculator.

Australian Safety Boundary

Arc-flash review in Australia depends on workplace electrical safety requirements, site procedure, equipment data, protection settings, available fault current, manufacturer information and competent study methods. This worksheet records entered values and user-defined threshold comparisons only.

Use the result as a triage record. Do not use it as an incident-energy value, PPE category, no-study conclusion, switching instruction or final work method.

Stop Points

The fault-current source is missing or not tied to the equipment location.
Clearing time and fault current do not belong to the same protection condition.
The working distance is guessed or copied from a different task.
The entered threshold is not tied to the project review basis.
The worksheet exceeds the entered user-defined triage threshold.
The row is being used as an incident-energy calculation.

Reference: AF-DB-1
Fault current: 8 kA
Clearing time: 0.08 s
Working distance: 450 mm

Fault current-time product0.64 kA.s
Screening index1.422 kA.s/m
Threshold margin1.078 kA.s/m
Statuspre-screening-record

Pre-screening index1.422 kA.s/m

56.9% of the entered threshold.

The entered values stay inside the user-defined triage criteria, so the row remains a record only and not a safe-work or no-study conclusion.

Prospective fault current is entered from the project source.
Clearing time is entered from the protection record.
The threshold is a user-entered review criterion.

Reference: AF-REVIEW
Fault current: 20 kA
Clearing time: 0.2 s
Working distance: 450 mm

Fault current-time product4 kA.s
Screening index8.889 kA.s/m
Threshold margin-6.389 kA.s/m
Statusstudy-referral

Pre-screening index8.889 kA.s/m

355.6% of the entered threshold.

The index and clearing-time criteria exceed the user-defined thresholds and should move to a competent arc-flash study basis.

The worksheet does not calculate incident energy.
The review threshold is entered by the user.
Site procedures and competent review can override the pre-screen.

Reference: AF-DISTANCE
Fault current: 10 kA
Clearing time: 0.1 s
Working distance: 300 mm

Fault current-time product1 kA.s
Screening index3.333 kA.s/m
Threshold margin-0.833 kA.s/m
Statusstudy-referral

Pre-screening index3.333 kA.s/m

133.3% of the entered threshold.

The shorter working distance increases the relative index and exceeds the entered review threshold.

Working distance is entered in millimetres.
The index is user-defined triage only.
Detailed task posture and equipment arrangement remain outside the worksheet.