DC Arc Flash Calculator

Calculator Inputs

Equipment name

Location

Calculation method

System voltage, V

Bolted fault current, A

Conductor gap, mm

Clearing time, ms

Working distance, mm

Arc configuration

Custom multiplier

Boundary threshold, cal/cm²

Correction factor

Assumptions and notes

Reset

Formula Used

This calculator uses simplified DC arc flash equations for screening and documentation support.

Source resistance: Rsource = Vsys / Ibf
Arc resistance: Rarc = (20 + 0.534 × G) / Iarc^0.88
Iterative arcing current: Iarc = Vsys / (Rsource + Rarc)
Maximum power option: Iarc = 0.5 × Ibf
Maximum arc power: Parc = 0.25 × Vsys × Ibf
Incident energy: E = Parc × Tarc × Mf × Cf / (4π × Dcm² × 4.184)
Boundary distance: D = √(Parc × Tarc × Mf × Cf / (4π × 4.184 × Ethreshold))

Vsys is system voltage. Ibf is bolted fault current. G is gap in millimeters. Tarc is clearing time in seconds. Dcm is working distance in centimeters. Mf is the enclosure multiplier. Cf is the correction factor.

How to Use This Calculator

Enter the equipment name and location.
Select the calculation method.
Enter system voltage and available bolted fault current.
Add conductor gap, clearing time, and working distance.
Choose open air, enclosed equipment, or a custom multiplier.
Enter a correction factor if your study requires one.
Press Calculate to view results below the header.
Download CSV or PDF for record keeping.

Example Data Table

Example	Voltage	Fault Current	Gap	Clearing Time	Distance	Configuration
Telecom battery cabinet	125 V	8,000 A	25 mm	100 ms	455 mm	Open air
Industrial DC panel	250 V	14,000 A	32 mm	160 ms	610 mm	Enclosed
Solar combiner study	600 V	6,500 A	50 mm	80 ms	910 mm	Custom

Understanding DC Arc Flash Risk

A direct current arc flash can release heat, pressure, and light quickly. Batteries, chargers, drives, solar strings, and transit equipment can support sustained arcs. The danger changes with voltage, fault current, conductor gap, clearing time, enclosure shape, and working distance. This calculator gives a structured estimate. It is not a final engineering study.

Why DC Arcs Need Care

DC faults behave differently from many alternating current faults. Current may not cross zero naturally. Protective devices can take longer to interrupt. A battery bank can deliver high current until protection opens. A photovoltaic source can also change current during the event. These details make conservative inputs important. Use verified equipment data whenever possible.

What This Tool Estimates

The form estimates arcing current, arc resistance, arc power, incident energy, and arc flash boundary. It also shows joules, watts, and a practical protection level. You can choose open air, enclosed equipment, or a custom multiplier. Enclosures can focus energy toward the worker. That is why the multiplier can increase the result.

How Results Should Be Used

Use the output for early screening, training examples, and documentation drafts. Compare several clearing times and distances. Small changes can move the hazard level. Longer clearing time usually raises incident energy directly. Greater working distance usually lowers exposure by the square of distance. This makes remote racking, insulated tools, and proper barriers valuable controls.

Good Input Practice

Start with the actual system voltage. Enter the maximum available bolted fault current from a study or manufacturer data. Use the real conductor gap when known. Enter total clearing time, including sensing and interruption. Select a distance that matches the worker position. Use the notes field to record assumptions. Export the report for review.

Important Limits

Arc flash studies require judgment. Equipment condition, electrode orientation, enclosure dimensions, maintenance, current limiting behavior, and local rules matter. Standards and company procedures may require different methods. Treat this calculator as an educational aid. Before performing energized work, request a qualified review. Use labels, permits, PPE, training, and safe work practices together. No calculator replaces de-energizing when that option is practical.

Review assumptions often with competent electrical safety leaders. Update studies after major equipment changes or protective adjustments.

FAQs

What is a DC arc flash calculator?

It estimates thermal exposure from a direct current arc. It uses voltage, fault current, gap, clearing time, distance, and configuration to estimate incident energy and boundary distance.

Can this replace an engineering study?

No. It is a screening and learning tool. Final arc flash labels and work procedures should be reviewed by a qualified electrical professional.

Why does clearing time matter?

Clearing time controls how long energy is released. Longer clearing time usually increases incident energy directly, so faster protection can reduce exposure.

Why is working distance important?

Incident energy drops as distance increases. The calculator uses distance squared, so even a moderate increase can reduce estimated exposure.

What is the enclosure multiplier?

It represents energy focusing caused by equipment shape. Enclosed equipment can direct more heat toward a worker than an open air arc.

What does the 1.2 cal/cm² threshold mean?

It is commonly used for arc flash boundary calculations. The boundary is the estimated distance where exposure reaches that selected threshold.

Which method should I choose?

Use the iterative method when you want arc resistance included. Use maximum power when you need a simple conservative screening comparison.

Why export CSV and PDF?

CSV helps with spreadsheets and audits. PDF helps with reports, training files, and review packages for supervisors or safety teams.