Skip to main content

Wiring Locks

This page covers wiring locking hardware — electric strikes and magnetic locks — to the AccessCore One controller's lock relay outputs.

This is the highest-stakes page in the wiring set. The relay outputs control whether a door is locked or unlocked, and one of these doors is almost always an egress door subject to life-safety code. Read the fail-secure vs fail-safe section before you land a single conductor.

:::danger Life-safety wiring Lock wiring affects egress. Magnetic locks on egress doors must release on a fire alarm condition and on loss of power. Coordinate every lock decision with the local fire code and the Authority Having Jurisdiction (AHJ). See Fire Alarm Integration. :::

Lock relay outputs​

Each door has one lock relay. The four relay outputs are on the top edge of the board, labeled DR1 through DR4.

OutputConnector refDoor
DR1J1Door 1
DR2J2Door 2
DR3J3Door 3
DR4J4Door 4

Each output is a Form C (SPDT) dry contact set — three terminals in silkscreen order COM, NO, NC (see the relay group on the board map in the Controller Overview).

PinSilkscreenFunctionWire to
1COMRelay commonOne side of the lock power loop
2NONormally open — open when idle/locked, closes when the relay energizes (door unlock)Fail-secure lock loop (electric strike)
3NCNormally closed — closed when idle, opens when the relay energizes (door unlock)Fail-safe lock loop (maglock)

:::caution These are dry contacts — the board supplies no lock voltage The relay terminals are dry contacts. The controller does not push any voltage out of COM, NO, or NC. You route the lock's own power supply through the contacts. The relay only opens and closes the circuit; the current and voltage that drive the lock come entirely from the lock power supply you provide. :::

The relay state follows the door:

  • Idle / locked — relay de-energized. COM–NC closed, COM–NO open.
  • Unlock (valid credential, REX, or scheduled unlock) — relay energizes. COM–NO closed, COM–NC open.

Confirm the controller is actually firing the relay during commissioning by the audible relay click and the lock responding.

Fail-secure vs fail-safe​

Choosing the wrong contact silently produces the wrong failure behavior — a strike that won't lock, or a maglock that traps people inside on a power failure. Pick the contact from the lock type and the door's required failure mode, not from convenience.

Lock typeFailure modeBehavior on power lossUse contact
Electric strikeFail-secureStays locked (door still free to exit mechanically)COM → NO
Magnetic lock (maglock)Fail-safeUnlocks (releases for egress)COM → NC

:::caution Match the contact to the failure mode A fail-secure lock (electric strike) is powered through COM → NO. The strike is only energized while the relay is active, so loss of power leaves it locked. Exit is still possible mechanically (lever/panic hardware).

A fail-safe lock (maglock) is powered through COM → NC. The lock is energized while the door is locked and de-energizes to release. Loss of power — at the relay, the controller, or the lock supply — drops the lock and frees the door. This is the required behavior for maglocks on egress. :::

Fail-secure: electric strike (COM → NO)​

Route the lock supply positive through the relay so the strike is energized only on unlock.

Fail-secure wiring — lock power supply through the relay COM and NO terminals to an electric strike

On unlock, COM–NO closes, the strike energizes, the door releases. On power loss the strike de-energizes and the door stays locked.

Fail-safe: magnetic lock (COM → NC)​

Route the lock supply positive through the normally-closed contact so the maglock is energized (locked) at idle and drops on unlock.

Fail-safe wiring — lock power supply through the relay COM and NC terminals to a magnetic lock

On unlock, COM–NC opens, the maglock de-energizes and releases. At idle the maglock is held energized (locked). On any power loss the maglock drops and the door unlocks.

:::danger Maglocks and egress A maglock holds a door shut by electromagnet. If it is wired so it can stay locked without power, it becomes a life-safety hazard. Always wire a maglock fail-safe (COM → NC), and ensure it also releases on fire alarm via the controller's fire input. See Fire Alarm Integration. Confirm the egress scheme with the AHJ. :::

Lock power​

The relay only switches the circuit — you must supply the lock's power.

  1. Determine the lock's voltage and current draw from the lock manufacturer's spec.
  2. Source the power:
    • You may use the controller's on-board 12 V supply only if the lock's draw fits within the controller's current budget alongside readers, fan, and battery charging. See Power & Enclosure.
    • Otherwise, use a dedicated lock power supply sized to the lock(s). This is the normal choice for maglocks and for multiple/large strikes.
  3. Common the grounds appropriately. When the lock supply and the controller share a logic relationship (or you are using one 12 V source for both), bond the supply grounds at a single point. Avoid ground loops — do not create multiple ground return paths between the lock supply and the controller.
  4. Run the supply through the relay contacts per the fail-secure or fail-safe diagram above. Never wire the lock straight across the supply bypassing the relay.

:::info Lock power is separate from reader power The +12V pin on each reader port is for powering the reader, not the lock. Do not power a lock from a reader port. See Wiring Readers. :::

For a UL 294-compliant installation, drive locking devices through a UL-listed fused relay/output board rather than switching the lock directly with the controller's onboard relay. The AccessCore One relay then provides control only — its COM / NO / NC output operates the listed board, and the listed board switches and fuses the actual lock current.

  • Why: the fused relay/output board carries the output fusing / power-limiting and the lock-current endurance, keeping the high-current, inductive lock load off the onboard relay contacts.
  • Direct wiring of a strike or maglock to the onboard COM / NO / NC relay (as described above) is supported for non-listed installations. For a compliant install, the fused relay/output board is the recommended, code-compliant method.
  • The fail-safe vs. fail-secure decision and the COM → NO / COM → NC choice still apply — they move to the listed board's output.

See Listing & Compliance for the full set of installation conditions.

Inductive spike suppression​

Locks are inductive loads. When the relay opens, the collapsing magnetic field produces a high-voltage spike that erodes relay contacts and can disturb the controller.

The board carries on-board MOV/varistor suppression across each relay. For long cable runs, also fit suppression at the lock, across the lock coil:

  • DC locks (strikes and maglocks): fit a flyback diode across the coil. Wire it reverse-biased — cathode (the banded end) to the positive lock terminal, anode to the negative terminal — so it conducts only when the coil de-energizes and clamps the spike.
  • AC locks: a diode will not work on AC. Fit an MOV (or RC snubber) across the coil instead.

:::caution Diode polarity A flyback diode installed backwards short-circuits the lock supply. Confirm the band (cathode) is on the + side of the coil before you power up. :::

Relay rating​

The relay contacts are dry Form C. Do not exceed the relay's contact rating with the lock load.

  • Keep the switched load within the relay's rating. For a high-current maglock, multiple locks on one door relay, or any load near the limit, drive an interposing relay (a separate power relay) from the AccessCore One contact and switch the heavy lock load through the interposing relay.
  • Always include inductive suppression (above) regardless of load size.

:::note No published amp figure This page does not state an exact contact-current rating because it is load-dependent. Size to the lock manufacturer's spec and the relay's published rating; when in doubt, use an interposing relay. :::

Fire alarm and egress interaction​

On a fire condition the controller drives the door relays to the unlock state so doors release for egress. For a maglock, this frees the door only if the lock is wired fail-safe (COM → NC), so that opening the NC contact de-energizes and drops the lock.

  • Maglocks on egress doors must release on fire alarm and on power loss.
  • Independent egress power-interrupt: the manual push-to-exit and the fire-alarm release must interrupt lock power in hardware at the power supply / relay board, independent of the controller. The controller's relay action is additive, not a substitute — see Listing & Compliance (Condition 4).
  • Wire and configure the fire input per Fire Alarm Integration, including the FIRE_MODE (NO / NC) jumper.
  • The egress release scheme is governed by local code and the AHJ. Do not finalize a maglock install without confirming the egress path.

Verify the door​

After wiring, commission each door before leaving it:

  1. Power the controller and the lock supply.
  2. With the door idle, confirm the lock is in its correct resting state — strike locked, maglock locked (energized).
  3. Trigger an unlock from the management software, or press the REX (see REX & Door Contacts).
  4. Confirm you hear the relay click and the lock physically releases.
  5. Release the unlock and confirm the lock returns to its resting (locked) state.
  6. Test the failure mode directly: drop the relevant power and confirm the lock behaves as designed — strike stays locked, maglock releases.

:::caution Always test the failure mode A relay that clicks proves the controller fires; it does not prove the failure mode is correct. Pull power and watch the lock to confirm fail-secure stays locked and fail-safe releases. :::