An automatic sliding door lock keeps an entrance secure after hours without anyone having to bolt the leaves by hand. On a powered door, locking is part of the operator: an electric lock engages when the door is switched to lock mode. This guide explains how an automatic sliding door lock works on the MC-125, how it ties into access control and escape routes, what happens in a power cut, and the parts and prices.
In this guide
How an automatic sliding door lock works
The MC-125 operator is electric-lock ready. When the door is set to lock mode on its mode switch, the leaves close and the electric lock engages, holding them shut. When the mode is changed back to automatic, the lock releases and the door opens for people again. See automatic door operating modes.
The lock and the other modes
- Automatic: lock released; the door opens for people on both sides.
- Exit only: used at closing time so people can leave but not enter.
- Lock: door closed and locked after hours.
Access control
An automatic sliding door lock can be combined with access control, such as a card or code reader, so staff can enter after hours while the door stays locked to the public. The MC-125 also supports two-door interlocking, where two doors in an airlock entrance are never open at the same time. See automatic door access control.
Escape routes and safety
A locked door must never trap people. How a locked automatic door behaves in an emergency is set by the building’s fire and escape strategy, confirmed by the fire consultant or local authority. Two options help on escape routes:
- Breakout: on the MC-125, an option that lets the leaves be pushed open outwards. See automatic sliding door breakout.
- Exit only mode at closing time, before switching to lock.
We set the door up to match the approved design; we do not issue compliance statements. See automatic door compliance.
Power cuts
With the optional battery backup, the MC-125 keeps running through load-shedding. How the lock behaves when power is lost depends on how it is set up, so discuss it at commissioning, especially on an escape route. See automatic doors during load-shedding.
Parts and prices
Prices for automatic sliding door lock parts are excluding VAT, at the time of writing (October 2026).
| Item | Price |
|---|---|
| MC-125 lock (replacement) | R1 257 |
| MC-125 complete automatic sliding door system | R27 590 |
| MC-125 control board | R6 966 |
The complete system is installed by MC Automations, Coetz™’s parent company, in Gauteng at that price; outside Gauteng, installation is quoted per project. See automatic door spare parts.
When the lock will not engage or release
Most faults with an automatic sliding door lock come from something simple:
- Check the mode switch is set to lock or automatic as intended.
- Check the leaves are fully closed; something in the track or floor guide can stop them meeting.
- Check the power and battery if the door has been through a power cut.
- Call a technician if it still will not lock; never force the leaves.
In Gauteng, call-outs are attended within 24 hours, at R1 450 excluding VAT within 60 km, then R7 per km. See automatic door troubleshooting guide.
Choosing the right locking set-up
| Entrance | Suggested set-up |
|---|---|
| Shop on a street | Lock mode after hours, exit only at closing |
| Office reception | Lock mode with card or code access for staff |
| Clinic or pharmacy | Lock mode plus access control; breakout if on an escape route |
| Airlock entrance | Two-door interlocking with the lock |
Tell us how the entrance is used, and the automatic sliding door lock is set up to suit it at commissioning.
Servicing
Service automatic doors every six months; the technician checks the lock, sensors, belt and rollers. The MC-125 carries a 24-month warranty on the operator and is tested to 1,000,000 operating cycles. The South African Bureau of Standards publishes the national standards framework.
Automatic sliding door lock: frequently asked questions
How do you lock an automatic sliding door?
Switch it to lock mode; the leaves close and the electric lock engages.
Can staff get in when the door is locked?
Yes, if the lock is combined with access control such as a card or code reader.
How much is a replacement MC-125 lock?
R1 257 excluding VAT.
Can people get out of a locked door in an emergency?
Escape behaviour is set by the building’s fire strategy. Breakout is an option on the MC-125 for escape routes.
Why will my automatic door not lock?
Usually the mode switch, something stopping the leaves closing fully, or a power issue. If not, call a technician.
Coetz™, Unit 2, 84 Ridge Road, Laser Park, Johannesburg. Call 010 412 0062, WhatsApp 076 613 4418 or use our contact page.
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