Calculate Arc Flash Boundary and Arc Flash Incident Energy with the Free Arc Flash Calculator. Supports IEEE 1584-2002, IEEE 1584-2018, and the Ralph Lee Method.
See Also
- 5 Minimum Arc Flash Label Requirements NFPA 2018.
- Cable sizing calculator AS/NZS3008
- Maximum demand calculator AS/NZS3000
Parameters for the IEEE 1584 2018 Arc Flash Calculator
- Standard: Select IEEE 1584-2018 or IEEE 1584-2002.
- Unit of measure: Imperial (in) or Metric (mm). Note that Conductor Gap is always in metric.
- Voltage (Vac): Enter an AC voltage between 208 V and 15,000 V.AC voltage levels outside of this range, and DC voltage levels, are not supported by the IEEE 1584-2018.
- Fault current (kA): Three-phase bolted prospective fault current in kA.
- Arcing time for Iarc (ms):
- The fault clearing time for the calculated normal arching current.
- Include the protection relay and circuit breaker clearing time.
- Follow a three-step process to specify the arching time:.
- Step 1: Leave the default time value, and click on Calculate.
- Step 2: Use the calculated arcing current Iarc to determine the actual fault clearing time for your protection system,
- Step 3: Click on Calculate again, to calculate the Incident Energy and Arc Flash Boundary.
- Note that the time does not affect the magnitude of the acing current.
- Arcing time for Iarc_min (ms):
- The purpose of this is to calculate the Incident Energy and Arc Flash Boundary for a scenario where the fault clearing time may be longer due to a reduced arcing current.
- This is the arcing time for the calculated reduced arcing current.
- Follow the same steps as explained above for the arcing time for the normal arcing current.
- Working distance (inch or mm): The working distance from the arc location. This field is pre-populated with typical distances from IEEE 1584 2018, which is based on the Equipment Type.
- Equipment Type:
- The Equipment Type is used to pre-populate the following distances and sizes with typical values from the IEEE 1584 2018:
- Working Distance.
- Enclosure Sizes (width, height, and depth).
- Conductor Gap.
- You can change these values after you have selected the equipment type.
- The Equipment Type is not used in the calculations. Only the values are used.
- The Equipment Type is used to pre-populate the following distances and sizes with typical values from the IEEE 1584 2018:
- Enclosure width, height and depth (inch or mm): You can change the typical enclosure (box) sizes here.These values are pre-populated with typical values from IEEE 1548 2018, based on the selected Equipment Type.
- Electrode configuration: Choose from the following:
- VCB: Vertical conductor (electrode) in a box.
- VCBB: Vertical conductor (electrode) in a box terminated in an insulating barrier.
- HCB: Horizontal conductor (electrode) in a box.
- VOA: Vertical conductor (electrode) in open air.
- HOA: Horizontal conductor (electrode) in open air.
- Conductor gap (mm): The distance between the conductors (electrodes).This value is always in mm.It is pre-populated with typical values from IEEE 1548 2018, based on the selected Equipment Type.
Parameters for the IEEE 1584 2002 Arc Flash Calculator
- Standard: Select IEEE 1584-2018 or IEEE 1584-2002.
- Unit of measure: Imperial (in) or Metric (mm). Note that Conductor Gap is always in metric.
- Voltage (Vac): Enter an AC voltage between 208 V and 15,000 V.AC voltage levels outside of this range, and DC voltage levels, are not supported by the IEEE 1584-2002.
- Fault current (kA): Three-phase bolted prospective fault current in kA.
- Arcing time for Iarc (ms):
- The fault clearing time for the calculated normal arching current.
- Include the protection relay and circuit breaker clearing time.
- Follow a three-step process to specify the arching time:.
- Step 1: Leave the default time value, and click on Calculate.
- Step 2: Use the calculated arcing current Iarc to determine the actual fault clearing time for your protection system,
- Step 3: Click on Calculate again, to calculate the Incident Energy and Arc Flash Boundary.
- Note that the time does not affect the magnitude of the acing current.
- Working distance (inch or mm): The working distance from the arc location. This field is pre-populated with typical distances from IEEE 1584 2018, which is based on the Equipment Type.
- Equipment Type:
- The Equipment Type is used to pre-populate the following distances and sizes with typical values from the IEEE 1584 2002:
- Working Distance.
- Conductor Gap.
- You can change these values after you have selected the equipment type.
- The Equipment Type is used in the calculations.
- The Equipment Type is used to pre-populate the following distances and sizes with typical values from the IEEE 1584 2002:
- Grounding: The grounding type is used in calculations.
- Conductor gap (mm): The distance between the conductors (electrodes).This value is always in mm.It is pre-populated with typical values from IEEE 1548 2018, based on the selected Equipment Type.
Ralph Lee Method
The calculator also supports the Ralph Lee Method,which is one of the proposed methods in theNFPA 70E standard.
PPE Categories in NFPA 70E 2018
There are two official Arc Flash Analysis (Study) methods defined by NFPA 70E:
- Incident Energy Analysis Method
- Arc Flash PPE Category Method
You can read more about it in What is an Arc Flash Study? Two Official Methods Described
This calculator is based on the Incident Energy Method.
According to NFPA 70E, PPE Categories should not be used when the Incident Energy Method is used.However, NFPA 70E allows site-specific PPE requirements on Arc Flash Labels, and in many cases, sites adopt the PEE Categories anyway.
For more information see 5 Minimum Arc Flash Label Requirements from NFPA 70E 2018
Therefore, I have included the mapping to Arc Flash Categories in the calculator.
The PPE in NFPA 70E is defined into 4 categories.
| Category | Minimum arc rating of PPE |
|---|---|
| 0 | 1.2 cal/cm2 |
| 1 | 4 cal/cm2 |
| 2 | 8 cal/cm2 |
| 3 | 25 cal/cm2 |
| 4 | 40 cal/cm2 |
Note that Category 0 is not listed in NFPA 70E.I have included it here when the incident energy is less than 1.2 cal/cm2.In other words, when the Arc Flash Boundary is less than the working distance.
Equipment types with typical distances and sizes for IEEE 1584 2018
Abbreviations used in Table 2 and Table 3:
| Gap | Conductor Gap (mm) |
| WD | Working distance (inch or mm) |
| H | Enclosure height (inch or mm) |
| W | Enclosure width (inch or mm) |
| D | Enclosure depth (inch or mm) |
| Equipment type | Gap mm | WD in | H in | W in | D in |
|---|---|---|---|---|---|
| 15 kV Switchgear | 152 | 36 | 45 | 30 | 30 |
| 15 kV MCC | 152 | 36 | 36 | 36 | 36 |
| 5 kV Switchgear, Large | 104 | 36 | 36 | 36 | 36 |
| 5 kV Switchgear, Small | 104 | 36 | 45 | 30 | 30 |
| 5 kV MCC | 104 | 36 | 26 | 26 | 26 |
| LV Switchgear | 32 | 24 | 20 | 20 | 20 |
| LV MCCs and Panels, Shallow | 25 | 18 | 14 | 12 | 8 |
| LV MCCs and Panels, Deep | 25 | 18 | 14 | 12 | 9 |
| Cable Junction Box, Shallow | 13 | 18 | 14 | 12 | 8 |
| Cable Junction Box, Deep | 13 | 18 | 14 | 12 | 9 |
| Equipment type | Gap mm | WD mm | H mm | W mm | D mm |
|---|---|---|---|---|---|
| 15 kV Switchgear | 152 | 914 | 1143 | 762 | 762 |
| 15 kV MCC | 152 | 914 | 914 | 914 | 914 |
| 5 kV Switchgear, Large | 104 | 914 | 914 | 914 | 914 |
| 5 kV Switchgear, Small | 104 | 914 | 1143 | 762 | 762 |
| 5 kV MCC | 104 | 914 | 660 | 660 | 660 |
| LV Switchgear | 32 | 610 | 508 | 508 | 508 |
| LV MCCs and Panels, Shallow | 25 | 457 | 355.6 | 305 | 203 |
| LV MCCs and Panels, Deep | 25 | 457 | 355.6 | 305 | 229 |
| Cable Junction Box, Shallow | 13 | 457 | 355.6 | 305 | 203 |
| Cable Junction Box, Deep | 13 | 457 | 355.6 | 305 | 229 |
Equipment types with typical distances and sizes for IEEE 1584 2002
| System voltage | Equipment type | Conductor gap |
|---|---|---|
| 0.208-1 kV | Open air | 10-40 mm |
| Switchgear | 32 mm | |
| MCCS and panels | 25 mm | |
| Cables | 13 mm | |
| >1-5 kV | Open air | 102 mm |
| Switchgear | 13-102 mm | |
| Cables | 13 mm | |
| >5-15 kV | Open air | 13-153 mm |
| Switchgear | 153 mm | |
| Cables | 13 mm |
| System | Working distance |
|---|---|
| 15-kV switchgear | 910 mm |
| 5-kV switchgear | 910 mm |
| Low-voltage switchgear | 610 mm |
| Low-voltage MCCs and panelboards | 455 mm |
| Cable | 455 mm |
How to calculate the Arc Flash Boundary with IEEE 1584 2018?
The Arc Flash Boundary is calculated according to IEEE 1584 2018 as follows:
- Calculate the intermediate arching currents Iarc_600, Iarc_2700 and Iarc_14300 at 600V, 2700V and 14300V.
- Calculate the final arcing current Iarc at the specified open circuit operating voltage Voc.
- Calculate the enclosure size correction factor CF for the relevant electrode configuration and enclosure size.
- Calculate the intermediate arc flash boundaries AFB600, AFB2700 and AFB14300 at 600V, 2700V and 14300V.
- Calculate the final arc flash boundary AFB at the specified open circuit operating voltage Voc.
How to calculate the Arc Flash Incident Energy with IEEE 1584 2018?
The Arc Flash Incident Energy is calculated according to IEEE 1584 2018 as follows:
- Calculate the intermediate arching currents Iarc_600, Iarc_2700 and Iarc_14300 at 600V, 2700V and 14300V.
- Calculate the final arcing current Iarc at the specified open circuit operating voltage Voc.
- Calculate the enclosure size correction factor CF for the relevant electrode configuration and enclosure size.
- Calculate the intermediate arc flash boundaries E600, E2700 and E14300 at 600V, 2700V and 14300V.
- Calculate the final Incident Energy E at the specified open circuit operating voltage Voc.
