Fail safe vs fail secure: electric strikes and maglocks

This section and those after it, unless dated otherwise, were checked on 1 October 2026 against the sources listed on this page.

Fail safe hardware needs power to stay locked, so it unlocks when the power goes off; fail secure hardware needs power to unlock, so it stays locked. HES calls the two power to lock and power to unlock. The mode governs the entry side: HES notes that, maglocks excepted, most electrified hardware allows free egress at all times in either mode.

What each mode does at the door

• Fail secure strike: with the power off the keeper stays locked, so the door stays locked from outside while people inside still leave through the lock or exit device.
• Fail safe strike: with the power off the door opens from outside. HES’s surface strike instructions describe fail safe keepers as unlocked without power and locked when power is applied.
• Maglock: HES says electromagnetic locks are only available fail safe. With the power off the M62 lets go completely; Securitron’s instant release circuit leaves no residual magnetism.
• Exit device with electric latch retraction: HES says these are only available fail secure.

HES’s own guidance puts fail safe on doors that must allow free egress on fire alarm activation or power failure, giving stairwell doors that require re-entry as its example, and fail secure where entry security is the concern. Its 1500 and 1600 instructions add that the suitability of fail secure operation is up to the local AHJ and that emergency exit hardware may be required. We supply listed hardware and confirm in writing the part number and options you have chosen. We are not code consultants; your Authority Having Jurisdiction (AHJ) makes the final call.

An electric strike for a mortise lock is one built for the ANSI 4-7/8 in strike prep, with a faceplate matched to the lock’s latchbolt and, where the lock has one, its deadbolt. For a mortise lock with up to a 3/4 in latchbolt and no deadbolt, HES’s selector guide lists its 1006, 1500 and 1600; for one with a 1 in deadbolt, the 1006 and 1600.

• Recapture: HES marks its 1006CS, 1006CDB, 1600 CS and 1600 CDB as not intended for continuous recapture of a 1 in deadbolt and points to the 1006CAS (HES lock cross reference).
• Faceplate by lock series: HES’s KM faceplates (1KM on the 1500 and 1600) fit the Sargent 7800, 8200 and 9200, Corbin Russwin, BEST and Accentra 8800 (formerly Yale Commercial) mortise locks; its KD faceplates fit the Sargent 7700 and 8100, Accentra 8700 and Dorma 9500. The 1500C, 1600 CLB and 1006CLB include both. HES gives these lists as recommendations and refers you to the lock maker’s documents.
• Strike position: HES sets the strike’s centerline 3/8 in above a mortise lock’s centerline; on a cylindrical lock the two line up (HES lock cross reference).
• Frame depth: the strike body is 1-3/8 in deep on the 1500, 1-5/8 in on the 1600 and 1-11/16 in on the 1006 (HES catalogs). Of the three, HES’s comparison chart shows only the 1500 installing in a fire-listed 2 in frame with 1/2 in drywall.
• Door pressure: HES notes that a mortise lock may need a strike with a deeper cavity, deadbolt support or preload capability, depending on latch design and door pressure; preload is pressure on the door that stops a standard strike releasing.

An electric strike or maglock needs a DC supply at its own voltage, 12 or 24 V, sized for the current of every device it runs. From the makers’ sheets: the HES 1500 and 1600 draw 240 mA at 12 V DC or 120 mA at 24 V DC, the HES 1006 480 or 240 mA, the HES 9600 500 or 250 mA and the Securitron M62 250 or 150 mA.

• Fail safe draws power the whole time it is locked. By HES’s definitions a fail safe device needs power to stay locked and a fail secure one only to unlock, so a fail safe strike or a maglock draws its current for as long as the door is locked. That is why a fail safe 1500 or 1600 runs on DC: HES rates them on AC for intermittent duty only. HES’s 2005M3 SMART Pac III cuts the initial voltage by 25 percent in timed or fail safe operation to extend a strike’s life.
• Add up every device. Securitron’s own worked example puts an M62 (0.25 A), a DK-26 access unit (0.16 A), an XMS motion sensor (0.05 A) and an EEB2 timer (0.025 A) on one 12 V DC supply: 0.485 A, rounded up to 0.6 A, which Securitron’s table wires in 18 gauge for a 200 ft run from the supply.
• Wire gauge rises with the run. HES gives minimum gauges by round-trip length: the 1006 takes 18 gauge up to 200 ft at either voltage, and the 1500 and 1600 take 20 gauge at 24 V for the same run.
• Meter the supply first. HES warns that many supplies run above their rating and that input more than 10 percent over the solenoid rating may cause severe damage, and it requires wiring to the National Electrical Code, NFPA 70.

HES lists its 1006, 1500 and 1600 strikes as UL 10C fire rated in fail secure mode only, at 3 hours on a single door and 1-1/2 hours on a pair, and the 9600 as not fire rated. UL certifies the Securitron M62 as an auxiliary lock for fire doors rated up to 3 hours with the B, D, BD or F suffix.

HES’s surface strike instructions say that converting a 9400, 9500, 9600 or 9700 to fail safe negates the unit’s fire rating, and fail safe should not be used in fire rated or windstorm resistant applications. HES’s selector guide lists a fire-rated assembly (NFPA 80 fire doors) among the special requirements to settle before choosing a strike. We supply listed hardware and confirm in writing the part number and options you have chosen. We are not code consultants; your Authority Having Jurisdiction (AHJ) makes the final call.