Corbin Russwin ML20932 NSB SEC Electrically Controlled Mortise Lock - Double Cylinder - Fail Secure - NSB Lever

The Corbin Russwin ML20932 SEC is the double cylinder, fail secure electrified mortise lock from the ML20900 ECL Series. It combines the proven ML2000 Series mortise lockcase with a self-contained continuous-duty solenoid, providing remote electrical control of the locking mechanism from any access control system, door controller, or power supply. If you're searching for "corbin russwin electric mortise lock" or using item references like ai20932 or ai10932 for specification purposes, this is the product.

What "Double Cylinder" Means on This Lock

Standard electrified mortise locks use a single cylinder outside and a thumbturn or free-rotating hub inside. The ML20932 uses a double cylinder configuration: a cylinder on the outside and a cylinder on the inside. When the solenoid is de-energized (locked state), both the outside and inside grips are locked. Neither side operates the latchbolt without a key.

This is specified on high-security doors where controlled egress is required, not just controlled entry. Pharmacies, vaults, data centers, detention facilities, server rooms, and evidence rooms are common applications. If someone inside needs to leave, they need a key. This prevents unauthorized exit as much as unauthorized entry.

Fail Secure: What Happens When Power Fails

SEC designates Fail Secure operation. When the lock loses electrical power, the solenoid de-energizes and the lock remains in the locked state. To unlock, power must be applied to the solenoid. This is the correct mode for applications where maintaining the secured condition during a power outage is the security priority.

The opposite configuration, the ML20932 SAF (Fail Safe), unlocks when power is removed, which is correct for life-safety egress applications where free egress must be maintained during emergencies. Specify SEC when the secured state must hold through power failures. Specify SAF when free egress during emergencies outweighs maintained security.

Solenoid Operation: Fail Secure Function Logic

In fail secure mode, applying voltage to the solenoid unlocks the lock. With voltage applied, the latchbolt operates freely by grip from either side. When voltage is removed (power cut or de-energized), the lock returns to the secured state and both grips are locked. The mechanical key override is always available regardless of electrical state on the double cylinder configuration, allowing authorized personnel with a key to enter or exit at any time.

Electrical Specifications

The solenoid is continuous, meaning it can remain energized indefinitely without overheating or degrading. Voltage options are 12VAC/VDC at 800mA or 24VAC/VDC at 390mA. Operating voltage must remain within plus or minus 10% of rated voltage. Monitor switch rating is 4A at 250VAC.

Optional monitoring modules include M91 (Latchbolt Monitor, SPDT switch for full latch extension), M92 (Request to Exit Monitor, monitors inside trim activation), and M105 (Security Monitor, two switches in series monitoring lock status and auxiliary latch position). Monitoring options are ordered in combinations: M91 with M92, or M92 with M105.

Lockcase and Physical Specs

Lockcase is heavy-gauge chrome plated steel, 5-7/8" x 4" x 15/16". Front is heavy-gauge steel, 8" x 1-1/4" x 3/32", accommodating flat and 1/8" beveled doors. Standard backset is 2-3/4". Door thickness is 1-3/4" standard. Latchbolt is a 2-piece mechanical anti-friction insert with 3/4" throw. Auxiliary latchbolt deadlocks the main latch. Cylinder is brass 6-pin, L4 keyway, 0-bitted standard. Strike is wrought brass or bronze ANSI straight lip, 4-7/8" x 1-1/4".

The ML20900 Series installs in a standard mortise door prep with slight modification by the door manufacturer. The solenoid is self-contained within the lockcase. Patented Quick Reversible latchbolt (Patent #6,349,982) allows field re-handing without disassembling the lockcase.

Certification: ANSI A156.13 Series 1000 Grade 1. Warranty: 5-year limited on the ML2000 mortise lockset, 1-year limited on electronic components.