Most South African gates already have a motor and a wall remote. What people want is the phone.
You do not replace a working Centurion, ET, or similar motor for that. You add a relay across the same trigger the wall button uses, put it in a box that does not drown, and you give the family an app button. Hardware we use for that job: the Sonoff gate and garage relay.
If the motor is dying, fix the motor. A smart relay on a dead gearbox is still a dead gate.
What you are actually adding
A momentary trigger. Same as pressing the existing button.
You are not:
- Replacing the control board “so it can be smart”
- Feeding the motor power through a 10 A Wi‑Fi toy
- Trusting the cloud as the only way to get into the yard
Keep the original remote. Keep the lock. Keep the beam. Smart is an extra button, not the safety system.
The steel-box problem
Gate motors live in metal housings at the end of the driveway. Wi‑Fi hates that.
Before you blame the relay:
- Stand at the motor with your phone. If LTE is fine and 2.4 GHz Wi‑Fi is one bar, the Sonoff will be one bar too
- A mesh node closer to the gate beats three “range extender” specials
- External antenna or a different mounting spot beats wrapping the module in the housing and hoping
Protocol chat for later: Wi‑Fi vs Zigbee vs Matter. For this job, Wi‑Fi is normal if the signal is real.
Wiring, in words an electrician can use
- Parallel the trigger / receiver input the wall button already hits
- Do not put the motor live through the Sonoff unless the unit and the amp rating were specified for that, which on this cheap relay they are not
- Isolate before you open the housing
- Use a waterproof box if the module sits outside the motor lid
- Label the extra pair so the next person does not rip it out
If that list is not obvious, this is not a first-time DIY. We do Gauteng installs. Photos of the open motor housing help. About.
Load shedding
The motor battery is the backup, not Home Assistant.
Test the battery with the grid off before you call the system finished. The relay only needs enough power to pulse the trigger. A flat motor battery plus a clever app is how people sit outside their own house.
Hub-side notes: Home Assistant during load shedding.
“Did I close the gate?”
A relay gives you control. It does not always give you state.
If you need open/closed on the phone, add a contact or use a motor that already reports position. Guessing from “I pressed the button” is how automations open the gate at 02:00.
What we tell complexes
Body corporates care about extra holes, extra boxes, and anything that looks like a second intercom. Ask before you drill. A module inside the existing housing with the original remotes still working is an easier conversation than a new pedestal.
FAQ
Will this work with Centurion / MyCentsys? Usually yes, as an extra trigger. We do not rip out the official radio unless there is a reason. Bring the board photo.
Can I use Shelly instead? Yes. See Sonoff vs Shelly. The Sonoff gate relay is the cheap default.
Can Home Assistant open the gate when I arrive? It can. Start with a button. Add geo-fencing after you trust the state sensor. Arrival automations without a contact are how gates open for the street.
What if Wi‑Fi never reaches the gate? Fix Wi‑Fi or run a different plan. Do not stack repeaters in the rose bush and call it done.
