ANSI/BHMA A156.31: Electric Strikes
Grading, wiring, and fire rating requirements for commercial electric strikes
Last updated: March 22, 2026
Contents
What is ANSI/BHMA A156.31?
ANSI/BHMA A156.31 is the performance standard for electric strikes and frame-mounted electric actuators. It covers the hardware that lets you remotely release a locked door without changing the lock itself. When someone buzzes you into an office lobby or badges into a hospital wing, an electric strike is doing the work.
The standard is maintained by the Builders Hardware Manufacturers Association (BHMA) and sets requirements for durability, strength, and operational performance. It applies to strikes used with cylindrical locksets, mortise locksets, and rim-mounted exit devices.
If you are specifying access control hardware for a commercial building, A156.31 grading tells you how long the strike will last and how much abuse it can take. Building codes and spec writers reference this standard to set minimum requirements for schools, hospitals, offices, and other occupied buildings.
BHMA Grading: Grade 1 vs Grade 2
A156.31 defines performance grades based on cycle testing and dynamic strength. Grade 1 is the top tier. Most commercial specs call for Grade 1, and manufacturers like Von Duprin and HES build the majority of their product lines to that level.
| Requirement | Grade 1 | Grade 2 |
|---|---|---|
| Cycle testing | 1,000,000 cycles | 500,000 cycles |
| Dynamic strength | 70 ft-lbs | 50 ft-lbs |
| Typical use | High-traffic commercial, institutional | Light commercial, interior doors |
| Fire-rated assemblies | Yes, when UL listed | Limited |
Cycle testing simulates years of daily use. At 100 operations per day, a Grade 1 strike rated for 1,000,000 cycles would last roughly 27 years before the mechanism wears out. Grade 2 at 500,000 cycles gives you about 13 years at the same rate.
Dynamic strength measures how much impact force the strike can absorb while staying functional. The 70 ft-lb Grade 1 rating accounts for someone slamming a heavy commercial door or applying force during an emergency. Grade 2 at 50 ft-lbs handles normal commercial traffic but is not suited for high-abuse locations like stairwells or emergency exits.
Tip: When a spec says "BHMA Grade 1 electric strike," it means A156.31 Grade 1 specifically. Do not confuse this with the A156.4 grading for door closers or A156.3 grading for exit devices. Each standard has its own grade definitions and test criteria.
Fail-Safe vs Fail-Secure
Every electric strike operates in one of two modes. Picking the wrong one can create a life-safety problem or a security gap. This is the single most important decision when specifying an electric strike.
Fail-Safe (Fail-Unlocked)
The strike stays locked when power is applied and unlocks when power is cut. During a power outage, the door is free to open.
- Required on fire-rated doors in most jurisdictions
- Meets fire and life safety egress codes (IBC, NFPA 101)
- People can always exit during an emergency, even without power
- Used on stairwell doors, exit corridors, and assembly occupancies
Fail-Secure (Fail-Locked)
The strike stays locked when power is cut and unlocks when power is applied. During a power outage, the door remains locked from the outside. The lever or knob on the inside still allows free egress mechanically.
- Maintains security during power loss
- Common on perimeter doors, server rooms, and restricted areas
- Mechanical free egress from inside is still required by code
- Not allowed on fire-rated doors unless specifically approved by the AHJ
Warning: Installing a fail-secure strike on a fire-rated door assembly can violate NFPA 80 and local fire codes. The authority having jurisdiction (AHJ) must approve any fail-secure application on a rated opening. When in doubt, specify fail-safe.
Voltage and Wiring
Electric strikes typically run on low-voltage DC power. The two most common options are 12V DC and 24V DC. Some models accept a range (12-24V AC/DC), but DC is preferred for new installations because it allows the use of battery backup.
| Specification | 12V DC | 24V DC |
|---|---|---|
| Typical inrush current | 300-600 mA | 150-300 mA |
| Typical holding current | 150-250 mA | 75-125 mA |
| Max wire run (18 AWG) | ~200 ft | ~400 ft |
| Common power supply | 1A @ 12V DC | 1A @ 24V DC |
| Battery backup | 12V sealed lead-acid | 24V sealed lead-acid |
Power Supply Sizing
Size your power supply for inrush current, not holding current. If you are running multiple strikes off one supply, add up the inrush current of all strikes that could fire simultaneously. A good rule of thumb: use a power supply rated at 150% of your calculated peak draw.
Tip: Use 24V DC for long wire runs. Voltage drop over distance is the most common cause of electric strike issues in the field. At 200+ feet, a 12V system may not deliver enough voltage to reliably actuate the strike. Check the manufacturer's voltage drop tables before finalizing your wire gauge and run length.
Fire Rating Compatibility
An electric strike installed on a fire-rated door must not compromise the fire rating of the assembly. This means the strike itself must be tested and listed as part of a fire-rated assembly per UL 10C (positive pressure fire test for door assemblies).
- UL listed: The electric strike must carry a UL listing for the specific fire rating (20-min, 45-min, 90-min, or 3-hour)
- Assembly tested: The strike must be tested as part of a complete door/frame/hardware assembly, not just individually
- Fail-safe required: Fire-rated openings almost always require fail-safe operation so the door can close and latch during a fire
- No hold-open: Electric strikes on fire doors must not hold the door open unless connected to the fire alarm system for automatic release
- NFPA 80 inspection: Fire-rated electric strikes must be included in the annual fire door inspection per NFPA 80
Common fire-rated electric strike applications:
| Fire rating | Typical location | Strike requirement |
|---|---|---|
| 20-minute | Corridor doors, residential | UL listed, fail-safe |
| 45-minute | Corridor doors, business occupancy | UL listed, fail-safe |
| 90-minute | Stairwell doors, exit enclosures | UL listed, fail-safe, Grade 1 |
| 3-hour | Fire walls, occupancy separations | UL listed, fail-safe, Grade 1 |
Warning: Swapping in a non-listed strike on a fire-rated door voids the entire assembly rating. The door, frame, and all hardware must be listed together. Always check the manufacturer's fire listing documentation before installation. Your firestop inspector will flag this.
Compatible Locksets
Electric strikes work by releasing the latchbolt, so the strike must match the type of lock installed on the door. Using the wrong strike for your lockset type is a common mistake that leads to callbacks.
Cylindrical Locksets
Standard lever or knob locks with a spring-loaded latchbolt (typically 1/2" to 5/8" throw). These are the most common locks in commercial buildings and have the widest selection of compatible electric strikes.
- Most electric strikes are designed for cylindrical locksets
- Latch throw of 1/2" to 5/8" is standard
- Strike must accommodate the latch lip geometry
- Works with brands like Schlage, Sargent, and Yale
Mortise Locksets
Heavier-duty locks with a full mortise body recessed into the door edge. Mortise locks have a longer latchbolt throw (up to 3/4") and a separate deadbolt. The electric strike only releases the latchbolt, not the deadbolt.
- Requires a strike rated for 3/4" throw latchbolts
- Deadbolt must be retracted separately (usually by thumbturn or key)
- Common in institutional and high-security applications
- Brands include Sargent, Corbin Russwin, and BEST
Rim Exit Devices
Panic bars and exit devices mount on the door surface and use a Pullman-type latchbolt. Electric strikes for rim exit devices are larger and heavier-duty than standard strikes.
- Requires a strike specifically designed for rim exit device latch geometry
- Must handle higher forces from panic hardware
- Often Grade 1 rated for code compliance on exit paths
- Compatible with Von Duprin, Sargent, and Precision exit devices
Tip: Always verify compatibility with the specific lock model, not just the lock type. Faceplate dimensions, latch projection, and lip length vary between manufacturers. Most electric strike manufacturers publish compatibility charts for major lock brands.
Selection Guide by Application
Use this table to narrow your search based on the building type and door function. These are starting points. Always confirm the final spec with your architect or security consultant.
| Application | Grade | Mode | Fire rated | Notes |
|---|---|---|---|---|
| School classroom | Grade 1 | Fail-safe | Often yes | Lockdown capability needed |
| Hospital patient wing | Grade 1 | Fail-safe | Yes | High cycle count, quiet operation |
| Office suite entry | Grade 1 or 2 | Fail-secure | Varies | Card reader or intercom release |
| Retail stockroom | Grade 2 | Fail-secure | Rarely | Lower traffic, security priority |
| Stairwell / exit door | Grade 1 | Fail-safe | Yes | Must work with exit device |
| Server room | Grade 1 | Fail-secure | Varies | Audit trail from access control |
| Apartment lobby | Grade 1 | Fail-safe | Often yes | Intercom or video release |
For exit paths and fire-rated doors, always specify Grade 1 with fail-safe operation. Grade 2 is acceptable for interior doors that are not on an exit path and do not carry a fire rating.
Frequently Asked Questions
Can I replace a mechanical strike with an electric strike on an existing door?
Yes, in most cases. The electric strike replaces the standard strike plate in the door frame. You will need to enlarge the frame prep (the cutout in the frame) to fit the electric strike body, and run low-voltage wiring to the location. On fire-rated doors, the replacement strike must carry the same fire listing as the original assembly.
What is the difference between an electric strike and an electric lock?
An electric strike replaces the strike plate in the frame and works with your existing mechanical lock. An electric lock (like a maglock or electrified mortise lock) replaces the lock itself. Electric strikes are simpler to install and less expensive, but they only control entry from one side. The mechanical lock still provides free egress from the inside.
Do I need a separate power supply for each electric strike?
Not necessarily. A single power supply can run multiple strikes as long as it is rated for the combined inrush current of all strikes that could activate at the same time. Size the supply at 150% of peak calculated draw and keep wire runs within the voltage drop limits for your chosen voltage (12V or 24V DC).
How do I know if my door needs a fail-safe or fail-secure strike?
Check the door's function in the building's egress plan. If the door is on a fire-rated wall, exit path, or stairwell, you almost certainly need fail-safe. Fail-secure is for doors where maintaining lock security during a power outage is the priority, like exterior perimeter doors or restricted areas. When in doubt, ask the fire marshal or the authority having jurisdiction (AHJ).
Will an electric strike work with my panic bar?
Yes, but you need a strike designed specifically for rim-mounted exit devices. Standard cylindrical lockset strikes will not fit the Pullman-type latch on a panic bar. Check the exit device manufacturer's compatibility list. Von Duprin, Sargent, and Precision all publish approved electric strike pairings for their exit devices.
What maintenance does an electric strike require?
Electric strikes are low maintenance. Test the strike monthly by triggering it from the access control system and confirming it releases and re-locks properly. Check wiring connections annually. On fire-rated doors, the electric strike must be included in the annual NFPA 80 fire door inspection. Replace any strike that shows sluggish operation or fails to fully release the latch.
Electric Strikes at US Made Supply
Browse our selection of ANSI/BHMA A156.31 rated electric strikes for commercial access control. All products include manufacturer documentation, wiring diagrams, and compatibility information.
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