Arc resistant switchgear,Built to the test report, not the marketing
Type 2B arc resistant LV and MV switchgear tested to IEEE C37.20.7. Fast bus protection, optical arc flash detection, and zone-selective interlocking integrated by default. Documented end to end for the AHJ and your insurance carrier.
- Type-tested standard
- IEEE C37.20.7
- Front, sides, rear
- Type 2B
- 480V through 15kV
- LV & MV
- Bus protection trip
- Cycle-fast
Why It Matters
Arc resistance is a tested rating, not a feature you can claim.
- A rating earned by testing, not by claim
Arc resistant switchgear is a type-tested rating under IEEE C37.20.7. Type testing means a sample lineup, in the exact configuration, was subjected to an actual internal arcing fault and met the criteria for personnel protection. A label without the test report behind it is marketing, not protection.
- Engineered to preserve the rating
Most of the field failures we see in arc resistant switchgear come from modifications that quietly invalidated the rating: a different breaker, a different relay, a venting path that was field-modified. Every lineup we engineer is built to keep the type-tested configuration intact, end to end.
- Fast clearing reduces the energy at the source
Arc-resistant construction contains and vents the fault. Fast clearing keeps it from getting bigger in the first place. We integrate optical arc flash detection, zone-selective interlocking, and fast bus protection to clear the fault in a single cycle where applicable.
- Documented for the next 30 years
Type test reports, qualifying documentation, IEEE C37.20.7 compliance basis, arc flash study, NFPA 70E labels, and the as-built drawings. Everything the AHJ, your insurance carrier, and the next engineer will ask for.
Accessibility Types
Which surfaces and conditions the rating actually covers.
- Type 1
Front only
- Personnel protection on the front of the lineup with the doors closed and latched. Common for installations with restricted access on the sides and rear.
- Type 2
Front, sides, rear
- Personnel protection on all enclosed sides with the doors closed and latched. The common rating for most modern arc resistant installations.
- Type 2B
Type 2 + low-voltage compartment
- Type 2 protection with the low-voltage instrument compartment door open for routine relay and metering access. The most common rating we engineer to because it reflects how operators actually work on the gear.
- Type 2C
Type 2 + adjacent compartments
- Type 2 protection between adjacent compartments inside the lineup. Required for installations where a single fault should not propagate to neighboring breaker cells.
What Goes Into the Design
Six engineered elements every arc resistant lineup includes.
- Pressure-relief venting
Engineered plenums and ducts route fault pressure away from the operator-facing surfaces. The path is part of the type-tested configuration, not field-improvised.
- Reinforced enclosure
Doors, panels, and structural elements designed and verified to withstand the dynamic pressure of an internal arcing fault without door blowout or panel detachment.
- Optical arc flash detection
Light-sensing arc flash relays inside the compartments detect ignition in under a millisecond and trip the upstream breaker in a single cycle. Coordinated with the bus protection.
- Zone-selective interlocking and fast bus protection
Coordination logic that lets the breaker closest to the fault clear first, fast, without waiting for time-graded coordination. Reduces incident energy by an order of magnitude.
- Vent path and stack design
For indoor installations, the venting path runs into a plenum, a chase, or an outdoor stack. Part of the engineering package, not an installer afterthought.
- Remote racking and switching
Operators perform racking and switching from outside the arc flash boundary using remote racking devices and wireless controls. Reduces personnel exposure even further.
Specifications
The technical envelope.
- Standard
- IEEE C37.20.7 Guide for Testing Metal-Enclosed Switchgear for Internal Arcing Faults
- Voltage class
- Low voltage 208V through 600V; medium voltage 4.16kV through 15kV class
- Accessibility ratings
- Type 1, Type 2, Type 2B, Type 2C; configured to the application
- Arcing fault current
- Type tested to the rated short-time current of the lineup
- Arc duration
- 0.5 seconds typical for the type test; coordinated with the protection scheme to clear faster in service
- Fast protection
- Optical arc flash detection, zone-selective interlocking, fast bus protection, configurable per application
- LV breakers
- Drawout low voltage power circuit breakers (UL 1066) in UL 1558 listed assemblies
- MV breakers
- Vacuum interrupters in IEEE C37.20.2 metal-clad assemblies
- Documentation
- Type test report, qualifying configuration documentation, arc flash study, NFPA 70E labels, PE-stamped engineering
The Retrofit Question
Modifying arc resistant switchgear is harder than modifying anything else.
Most failures we encounter come from modifications that quietly invalidated the rating. Here is how we keep that from happening.
- Modification invalidates the rating
Any change to the type-tested configuration (different breaker, different trip unit, different vent path) means the lineup is no longer running the configuration that was tested. The rating is invalidated until the new configuration is revalidated.
- Revalidation is engineering, not paperwork
Revalidating a modified arc resistant lineup either requires a new type test on the modified configuration, or engineering analysis demonstrating equivalence to the original test. We do both, depending on the scope of the change.
- Fast protection retrofit
Many lineups can be improved by adding optical arc flash detection, zone-selective interlocking, or fast bus protection without modifying the structural configuration. We retrofit the protection layer to reduce incident energy without affecting the type-tested rating.
- Documentation reconstruction
For older arc resistant lineups where the original type test documentation has been lost, we work with the OEM (where available) or perform the engineering analysis required to rebuild the qualification basis. Without that, the rating is not provable.
How It Works
From application review to documented commissioning.
- 01
Application review
Accessibility requirement (Type 1, 2, 2B, 2C), voltage class, fault current, and operator workflow. Sized for what the operators actually do, not the spec template.
- 02
Engineering and qualification
PE-stamped engineering package, IEEE C37.20.7 qualification basis, arc flash study, NFPA 70E labels, and the documentation the AHJ will ask for.
- 03
Build, test, install
Factory build of the type-tested configuration, witnessed acceptance test on request, then field install and commissioning.
- 04
Commission and document
Full functional test, arc flash labels installed at energization, operator training, and the complete documentation handoff. ControlCom Connect activated.
In the Field
What an arc resistant lineup looks like installed.
Arc resistant switchgear lineup with the venting plenum routed up and out, optical arc flash relays visible in the low voltage compartment, and IEEE C37.20.7 Type 2B labeling on the cabinet
1920 × 1080 (16:9)
Who It Is For
Built for the places personnel work on energized gear.
Healthcare
Hospital service entrance, surgical suite distribution, and essential electrical systems where operator safety is non-negotiable.
Data Centers
Critical distribution where remote racking, fast clearing, and personnel protection are required for concurrent maintainability.
Utilities & Generation
Substations, generation plants, and switchyards where worker safety on energized gear is a daily operational requirement.
Industrial & Process
Plants where operator exposure during routine racking, testing, and maintenance has to stay inside Cat 2 PPE without restriction.
Related
Deeper reading and adjacent work.
- 01
Low voltage switchgear
UL 1558 platform that the LV arc resistant lineups are built on.
- 02
Paralleling switchgear
Multi-generator paralleling, often specified arc resistant.
- 03
Custom switchgear
Engineered to your single-line, fault current, and operating modes.
- 04
Switchgear retrofit guide
Standards (IEEE C37.59 and C37.20.7), arc flash, and what zero-downtime really means.
- 05
Switchgear retrofitting service
Zero-downtime modernization with arc-resistant rating preserved.
Common Questions
Answers from our engineering team.
Talk to a Power Systems Engineer
Tell us the accessibility type you need, the voltage class, the fault current, and whether this is new or a retrofit. We will get back within 24 hours.
- Reviewed by a power systems engineer, not a salesperson
- IEEE C37.20.7 qualification documentation included
- Arc flash study and NFPA 70E labels at energization
- Vendor-neutral, fully documented, ControlCom Connect ready
Tell us about your arc resistant project
Accessibility type, voltage class, fault current, and whether it is new or a retrofit.