How Do Automatic Doors Work: Clear MC-125 Example

How do automatic doors work? It is the question every building owner asks before fitting one. The short answer: a powered operator, a set of sensors and a smart controller work together to open the door as you approach and close it safely behind you. This 2026 guide breaks down exactly how do automatic doors work — the parts, the cycle, and the differences between sliding and swing systems — for entrances across South Africa.

How Do Automatic Doors Work? The Basics

At heart, an automatic door replaces your hand with a motor. A sensor notices someone approaching and signals a powered operator, which moves the door open. The door pauses for a set time, then the operator closes it — gently, and only when the way is clear. A controller manages the timing, speed and safety behaviour, so the entrance feels effortless and stays safe all day.

The Four Parts of an automatic door

Every automatic door system is built from four working parts:

Operator — the motor unit above the door that drives it open and closed.
Activation sensor — a motion or microwave sensor that detects approach and triggers opening.
Safety sensor — a presence sensor that stops the door closing on a person, trolley or wheelchair.
Controller — the brain that sets speed, hold-open time and links to access control or the fire alarm.

Understanding these four parts is the key to understanding how do automatic doors work in any building.

The Opening Cycle, Step by Step

The cycle is the same for every system:

Detect — the activation sensor sees someone approach.
Open — the operator drives the door open at a set speed.
Hold — the door stays open for an adjustable dwell time.
Close — the operator closes the door, reversing instantly if the safety sensor detects an obstruction.

Add battery backup and the whole cycle keeps running through load shedding, failing safe-open on power loss.

How Automatic Sliding Doors Work

In a sliding system like the MC-125, the operator turns a toothed drive belt that glides the glass panel sideways along a track. Sliding doors suit wide, high-traffic entrances — retail, malls and receptions — because they move a lot of people quickly and look premium. Learn more in our sliding door motor guide.

How Automatic Swing Doors Work

A swing system like the MCW-100 uses an arm to push or pull a hinged door open. Swing operators suit single-leaf and accessible entrances — offices, clinics and access-controlled rooms — and retrofit neatly onto doors you already have. See our automatic door opener guide for detail.

How Automatic Doors Stay Safe

Safety is central to how do automatic doors work. Activation sensors open the door before you reach it, while safety sensors hold it open while anyone is in the threshold and reverse it on contact. Adjustable force and speed keep movement gentle, and quality systems follow international standards such as EN 16005 for power-operated pedestrian doors. Sensor choice matters — see our sensor pricing guide.

Activation Options and access control

Automatic doors can be triggered in several ways to suit the building. Motion sensors open them for general foot traffic; touchless wave switches suit hygiene-sensitive areas; and push buttons give an accessible, deliberate open. For controlled entrances, the operator wires into keypads, card readers, intercoms or timers, so the door opens only for the right people at the right times. This flexibility is a big part of why the same operator can serve a shop, an office or a clinic.

Where Automatic Doors Are Used

Once you know how do automatic doors work, it is easy to see where they fit:

Retail and malls — wide sliding entrances for footfall.
Offices and receptions — a premium, hands-free first impression.
Hospitals and clinics — touch-free, hygienic movement.
Estates and access points — entrances tied to access control.

Compare complete options in our automated door systems guide, or start with automatic door systems.

Why Choose Coetz™

Coetz™ Glazing, with MC Automations Entrance Systems, supplies and installs automatic doors across South Africa — operators, sensors, accessories and support in one place, with installation in Gauteng and supply nationwide. Ready to move? Contact our team for a quote.

How Do Automatic Doors Work? FAQ

How do automatic doors know when to open? An activation sensor — usually motion or microwave — detects someone approaching and signals the operator to open. Do automatic doors work during load shedding? Yes — with battery backup they keep operating and fail safe-open on power loss. Are automatic doors safe? Yes — safety sensors stop and reverse the door on a person or obstruction, in line with standards like EN 16005.

The same sensors are what make a door touchless — opening hands-free on approach or a wave.

Getting a quote for an automatic door

If you are asking “How do automatic doors work?” because you are planning one, MC Automations, our parent company, can help: it supplies, installs and services automatic doors. To quote accurately, we need to know:

The opening. The width and height of the clear opening, with photos of the existing frame or shopfront.
Sliding or swing. The MC-125 automatic sliding door system is R27 590 and the MCW-100 swing door operator R15 900, excluding VAT.
Traffic. How many people use the entrance, and whether trolleys, prams or wheelchairs pass through.
Power. Whether there is a power point near the head of the door.
Installation. Installation is included in Gauteng; outside Gauteng it is quoted per project.
Service and warranty. We recommend a service every six months, and the operator carries a 24-month warranty.

Questions about how automatic doors work? Call 010 412 0062, WhatsApp photos to 076 613 4418, or price an automatic door in the online estimator.

What happens in a power cut or during load-shedding

An automatic door needs mains power to run its motor, so a power failure is the moment when the way it was set up really matters. What the door does when the power goes depends on the options chosen at installation:

Battery backup keeps the operator running for a period, so the door carries on opening and closing as normal.
Fail-open settings drive the door open when the power fails and leave it open, so nobody is trapped inside.
Fail-secure settings keep the door closed and locked, with a manual release so that it can still be opened by hand.
A manual release on every door lets staff move the leaves by hand once the operator has been disengaged.

With load-shedding part of daily life, we ask every client which of these behaviours suits their building before the door is installed. A shop that trades through outages usually wants battery backup, while a building that closes when the power fails may prefer the door to lock.

Programme modes and when to use them

Most automatic doors have a selector, often a key switch or a panel behind the counter, that changes how the door behaves during the day:

Automatic: the normal setting, opening for people coming in and going out.
Exit only: the door opens for people leaving but not for people arriving, which is useful at closing time.
Open: the door stays fully open, for deliveries or busy events.
Locked: the door stays closed and locked overnight or when the building is empty.
Partial opening: on many sliding operators the door can open to only part of its width in quiet periods, which reduces draughts and air-conditioning losses.

Setting the right mode for each part of the day is one of the easiest ways to make an automatic door safer and cheaper to run.

What common faults tell you about how the door works

Because an automatic door is a simple chain of sensor, controller and motor, most faults point straight to the part of the chain that needs attention.

The door does not open

The sensor is not detecting people, the door has been left in locked or exit-only mode, or the operator has no power. Check the mode first, then the power supply, before calling for a technician.

The door opens on its own

The motion sensor is usually too sensitive or aimed too far out, so it reacts to people walking past, swaying signage or plants inside the detection field. Re-aiming the sensor normally solves it.

The door closes too quickly or touches people

The closing speed or force has drifted out of adjustment, or the presence sensor is dirty or misaligned. Stop using the door in automatic mode and have it checked, because this affects safety.

The door is noisy or moves in jerks

Worn rollers, a slack belt or debris in the floor guide make the door run roughly. These are wear items that are replaced during a service, long before the operator itself needs attention.

Most of these problems are adjustments rather than breakdowns, which is why regular servicing keeps an automatic door working the way it was designed to.

How the sensor tells someone approaching from someone passing by

A good automatic door opens for people who want to go through it and ignores people who are only walking past. Modern motion sensors do this by looking at direction as well as movement: someone walking towards the door triggers it, while someone crossing in front of it at an angle does not. The size and shape of the detection field are set on site, so a door on a busy pavement can be tuned to react only to people who are clearly heading for the entrance.

The presence sensor works differently. Instead of looking for movement, it watches the opening itself and keeps the door open while anything is standing there, including a person who has stopped to wait or a trolley left in the doorway.

Do automatic doors work in rain and wind?

Yes, but the weather affects the way the door should be set up. Wind blowing against a swing door makes it harder to close, so exposed entrances are usually better served by a sliding door, which moves across the wind rather than against it. Rain can make the floor around the threshold wet, so mats and drainage at the entrance matter as much as the door itself. Sensors are normally mounted under the header, out of the rain, and are adjusted so that heavy rain falling past the opening does not trigger the door.

How quickly should an automatic door open and close?

There is no single right speed. Opening and closing speeds are set at commissioning to balance the flow of people against comfort and safety. A busy shop entrance is usually set to open briskly so that customers never have to wait, while a door in a retirement home or clinic closes more slowly and holds open for longer, so that people who move carefully are never rushed. If a door feels too fast or too slow, the settings can be changed during a service visit without replacing anything.

Servicing, spares and call-outs

We recommend a professional service every six months, with more frequent visits for very busy entrances such as malls. A visit checks and realigns the sensors, inspects the belt, rollers and guides, re-checks opening and closing force, and replaces wear parts before they strand the door. Wear items are replaced as part of servicing rather than under warranty.

We stock the operators, sensors, drive belts and control boards we fit, so a repair does not wait on an imported part. Automatic doors are installed and serviced nationwide, with call-outs within 24 hours in Gauteng.

What changes the price

Pricing for automatic doors? A 2026 Guide follows the opening width, the glass, the sensors and any access control, so a figure quoted without seeing the opening is a guess. Every project starts with a free site measure, which confirms the opening, the power supply and the traffic flow before a fixed price is quoted. Glazing is 6.38 mm laminated safety glass as standard, and frames are powder-coated to suit the building.

How the safety side actually works

Two sensor types work together on automatic doors? A 2026 Guide: motion detection to open on approach, and presence detection to hold the door while somebody stands in the opening. Add safety beams and a force limit and the door reverses rather than pushing. Most call-outs we attend are sensors knocked out of alignment by a trolley or a delivery, not motors that have failed.

We walk the opening with a trolley and at normal walking pace before handover, then record the speed, hold-open and force settings.

Can you automate a door we already have?

In most cases, yes — a swing operator such as the MCW-100 automates an existing hinged door up to 1,200 mm and 150 kg (interdependent).

How long is the warranty?

Two years on the operator, from the manufacturer. Wear parts — belts, rollers, guides and seals — are handled through servicing rather than warranty.

What the entrance is made of

Glass and frame decide how automatic doors? A 2026 Guide looks and how it behaves in use. The standard is 6.38 mm laminated safety glass; performance and tinted glass are options, quoted separately, where heat or privacy are a factor. Frames are powder-coated to the building colour, and slim sightlines keep more of the opening as daylight rather than aluminium.

Retrofit or new installation

Automating an opening that already exists is usually possible, and it is often the cheaper route. The questions are whether the head can carry an operator, whether the opening is square enough to run true, and whether power can reach the header. Where a hinged door is staying, a swing operator automates it; where the frontage is being replaced anyway, a new sliding installation is generally the better long-term answer.

When something goes wrong

Describe what the door is doing and a technician can usually name the cause before travelling: held open points to sensors or a detection zone problem, reversing points to an obstruction or force limit, and noise points to rollers, belt or guides. Because the operators, sensors, belts and control boards we fit are held in stock, most of those are fixed on the first visit.

Can access control be added later?

It can, but cabling into a finished ceiling costs more than specifying it with the door. Readers, push buttons, intercoms and time clocks are all straightforward at installation stage.

Can we choose a different glass?

Yes. The standard is 6.38 mm laminated safety glass, and tinted, obscured or performance glass can be specified, and is quoted separately, where the frontage needs it.

Automatic doors in short

If you are pricing automatic doors, send the structural opening sizes and a photograph and we will specify the system, the sensors and the glass against the traffic the doorway really carries. Automatic doors are supplied, installed and serviced by one team, with spares held locally.

Ask us about automatic doors and we will confirm the opening, the power supply and the traffic flow before quoting a fixed price.

Automatic doors at a glance

Pricing for automatic doors follows the opening width, the glass and the sensor layout.

How Do Automatic Doors Work? Sensors, Operators and Safety Explained