Corbin Russwin ML20987 ASN SEC Electrically Controlled Mortise Lock - Double Cylinder - Fail Secure - ASN Lever

The ML20987 SEC does not allow free egress from inside. A key is required to operate the inside lever. Installation is restricted to applications where applicable codes explicitly permit control inside egress. Confirm with the Authority Having Jurisdiction before specifying this product on any opening. Failure to comply with code requirements for egress can create hazardous conditions and constitutes a life safety violation.

The Corbin Russwin ML20987 SEC is the most restrictive configuration in the ML20900 ECL electrified mortise lock series: double cylinder, fail secure, key required from both outside and inside at all times. The outside lever unlocks only when the access control system energizes the lock. When de-energized, either by access control logic or by power failure, the outside lever locks. The inside lever is always rigid. At no point does either lever operate without a key. This function is not a standard commercial specification. It's designed for licensed, inspected, and approved institutional applications where staff-controlled egress is a clinical or security mandate.

For all Corbin Russwin electrified mortise locks, browse our Corbin Russwin lever locks catalog. For access control hardware and power supplies, view our electronic hardware catalog.

ML20987 SEC Function: Every State Explained

State one, access control energized (power on): Outside lever unlocks and operates the latch freely. Inside lever is still rigid. Key from inside is required to exit. The access control system has granted outside entry; exit from inside still requires a key.

State two, access control de-energized or power failure (fail secure): Outside lever locks rigid. Inside lever remains rigid. A key is required from either side to retract the latch bolt. No one enters from outside and no one exits from inside without a key. This is the fail secure behavior: the door stays fully locked on power loss.

State three, key operation: Key in the outside cylinder retracts the latch for outside entry regardless of electrical state. Key in the inside cylinder retracts the latch for inside egress regardless of electrical state. Both cylinders are always active and never disabled by the electric function.

Corbin Russwin ML20987 NSA SEC Technical Specifications

Series: Corbin Russwin ML20900 ECL. Function: SEC, Fail Secure, Double Cylinder. Outside grip: unlocked when energized (power on); locked when de-energized (power off, fail). Inside grip: ALWAYS RIGID. Key both sides required at all times. Auxiliary latchbolt: deadlocks latchbolt when door closes. Trim: NSA, NS Lever (Newport), A Rose, 626 Satin Chrome. Trim restriction: NOT available with L, R, or V escutcheon trim. Voltage: 12/24 VDC. Continuous current: 15mA. Peak current: 0.5A maximum; maximum 2 locks per 1A power supply. Monitor switch rating: 2A at 24VDC. Door thickness: 1-3/4" (44mm) standard. Backset: 2-3/4" (70mm). Handing: quick reversible without disassembling lock case. Lockcase: heavy-gauge chrome plated steel, 5-7/8" x 4" x 15/16". Latchbolt: 2-piece with anti-friction insert, 5/8" x 1" x 3/4" throw (19mm). Auxiliary latchbolt: 9/16" effective throw, 3/8" effective deadlocking. Cylinder: 6-pin, L4 keyway standard; 7-pin optional; IC available. Both inside and outside cylinders. Keys: two nickel silver standard. Keying: KD standard; Keyed Alike (+$20); Master Keyed (+$30); Construction Master Keying. Monitor options: M91 latchbolt monitor; M92 REX monitor. Warranty: 10-year limited.

Where This Function Is Code-Permitted

The ML20987 SEC is permitted only in specific code-approved applications. These typically include licensed psychiatric facilities and behavioral health units operating under applicable state mental health codes, correctional and detention facilities under NFPA 101 Chapter 23 provisions for use condition III or higher, and certain government and military facilities with AHJ-documented security requirements. In every case, the building's fire authority, life safety code compliance officer, and licensing board must approve the installation in writing before the lock is specified. This is not a lock that can be installed based on the customer's preference alone.

ML20987 SEC vs. ML20907 SEC vs. ML20906 SEC

The three fail secure options in the ML20900 ECL series differ in cylinder configuration. The ML20906 SEC is single cylinder with mechanical cylinder override: key from outside can retract latch even when electrically locked; inside lever is always free for egress. The ML20907 SEC has no cylinder override: electric access only from outside when locked; inside lever is always free for egress. The ML20987 SEC (this product) is double cylinder: key from either side at all times; inside lever always rigid; no free egress from inside in any state.