THE PORCH LIGHT
Hi there!
Two months ago, a maker called deebuildsthings built a robot desk lamp that could see and hear. Now it talks with more feeling, senses the air in the room, and once noticed the kitchen getting stuffy before its owner did. It's open source, so if you're handy, you can build your own.
It got us thinking about what actually runs in our homes, and what keeps running when the power goes out. Many of us have an inverter by now; plenty don't. Either way, the question's the same: what's worth powering? So we worked it out, appliance by appliance, at this year's tariffs.
We also look at:
A smart plug that shows what each appliance costs you
Why your gate won't open in a power cut
A power-cut alert, straight to your phone
Hackers who heated supermarket fridges
And way, way more…
Got an inverter setup you're proud of, or one that keeps tripping? Hit reply and tell us.
Justin, Kobus and Rowen
THE BIG ONE · POWER
What to put on your inverter and what to leave off
Got an inverter? Then someone already decided what runs off it in a power cut. Most of us never checked.
In April, a viral TikTok list ranked the 20 biggest power users in an SA home at a flat R3.50 a unit. Tariffs went up on 1 July, so we redid the sums at this year's rates and added the part the list skipped: what each one does to your inverter.
What we used
Appliance draws and daily hours from the City of Cape Town's energy cheat sheet
Cape Town's Domestic rate of R4.14 a unit, including VAT
A common home setup: a 5kW Sunsynk inverter and one 5.32kWh battery, which gives you 4.79kWh to use
Appliance | Draws | Per month | On the inverter? |
|---|---|---|---|
Geyser | 2,600W | R1,420 | Leave off |
Stove and oven | 3,000W | R745 | Leave off |
Microwave | 1,200W | R119 | Yes, one at a time |
Kettle | 1,900W | R71 | Yes, one at a time |
Fridge-freezer | 150W | R93 | Yes |
TV | 125W | R93 | Yes |
Wi-Fi router | 12W | R36 | Yes |
Alarm | 10W | R30 | Yes |
Gate motor | 300W | R19 | Yes |
Leave the heaters off
The geyser alone would empty that battery in under two hours. The stove would do it faster. They're also your two highest costs, which is why the geyser and the pool pump typically sit on the non-essential side, the one that goes dark in a power cut.
The kettle is fine, but not with the microwave all at once
A kettle draws a lot, but not for long. A typical day's boiling uses about 12% of the battery. The trouble is everything at once: kettle, microwave and a 1,500W toaster together pull 4,600W, right up against the inverter's 5,000W limit. And one battery is built to deliver about 2,500W comfortably. In a power cut, run one heating appliance at a time.
How long the essentials last
Fridge, TV, router, alarm and ten 12W energy-saver bulbs all on at once draw about 420W. On one battery, that's around 11 hours, and longer in practice, since a fridge's compressor doesn't run all the time.
Work out your own
The label on each appliance gives its watts. For the monthly cost: watts ÷ 1,000 × hours a day × 30 × your rate per unit. Moving a circuit on or off the inverter is a job for an electrician.
The signal
Put what keeps you safe and connected on the inverter: fridge, Wi-Fi, alarm, gate and lights. Leave the geyser and stove off. Use the kettle and microwave one at a time, and one battery gets you through the night.
FIVE SIGNALS
Smart insights, short and sweet
POWER Your extension cord isn't an EV charger. Portable EV chargers draw up to 3.7kW for hours, and a cord rated 16A max can overheat under that steady load. Signal: Charging an EV is an all-night job, so it needs a socket and cable built for that, not a garden cord.
SAFE AND SOUND Hackers heated up supermarket fridges. A cyberattack pushed fridges at about 150 stores in France to 50°C for six hours, and the food was thrown away. The supplier says the hacked units were running outdated firmware. Signal: Old firmware is the open door: check your smart appliances and router for updates this week.
CONNECTIVITY MTN hits 10Gbps on 5G. MTN and Huawei reached 10.35Gbps download speeds in Africa's first 5G-Advanced trial on the upper 6GHz band, run at MTN's Randburg head office on a temporary licence. Signal: It's a trial, not a product, so don't expect those speeds on your router just yet.
SAFE AND SOUND Cash-in-transit industry calls for special courts. Four cash-in-transit guards were killed in attacks in September. The industry's association wants special courts and trained prosecutors, saying almost all the attackers are out on bail for similar crimes. Signal: The ask is to keep repeat offenders off the streets rather than add more armour.
WORK AND PLAY Free AI-made clones of Word, Excel and PowerPoint. The developer who used AI to clone Adobe's apps has released open-source lookalikes of Microsoft Office called WordCraft, GridCraft and DeckCraft. They're earlier in development than his Adobe clones. Signal: Fun to try, but keep your important work in software someone's committed to fixing.
WORTH IT?
CBI Astute Smart Adaptor
R269 at Chamberlain
BUY to see what your fridge, kettle or TV really costs to run. WAIT if it's the geyser or stove you want to measure.
Plug it into the wall, plug an appliance into it, and the CBI Home App shows how much power it's using. It's made by South African electrical brand CBI and handles 16A, so even a kettle is fine. It also works with Google Assistant and Alexa. Measure an appliance for a week, then move the adaptor to the next one. That's the main section's maths, done on your own appliances.
The catch is that your two highest costs, the geyser and the stove, are wired straight into the board, so no plug can measure them. It also needs 2.4GHz Wi-Fi and an internet connection to report anything.
THE FIX
Your gate won't open when the power's off
When the power goes out, your gate motor switches to its own battery, and the mains recharges it when the power comes back. So if the gate dies in a power cut, it's usually the battery, not the motor.
01 Open it by hand. Unlock the manual release with the key that came with your motor, then slide the gate. Keep that key somewhere you can reach from inside the property.
02 Check the battery's age. A gate motor battery lasts two to three years. If the gate runs slowly on battery, or stops before it's fully open, the battery is on its way out. Replace it.
03 Save it in long outages. If the power's out for more than four hours, put the gate on manual so the battery isn't run flat.
ONE AUTOMATION
Get an alert the moment the power goes off at home
WHEN the power goes off at home
THEN the Olarm APP sends you a notification
AND you know straight away, wherever you are
Handy when you're at work with a full fridge, or away for the weekend.
01 Open the Olarm APP, tap the menu icon (≡) in the top-right corner, then App Permissions. Make sure Push Notifications is on.
02 On iPhone, open Settings, tap Apps, choose Olarm, tap Notifications and switch on Allow Notifications. On Android, open Settings, tap Apps, choose Olarm, tap Notifications and switch them all on.
03 On Android, check that Olarm isn't restricted under Battery Optimisation, or alerts can arrive late.
04 Test it: arm and disarm your alarm. If both notifications come through, you're set.
EVENTS
Coming up
Solar & Storage Live Cape Town · 20–21 October · CTICC, Cape Town. Home solar, batteries and EV charging, with a free-to-attend exhibition.
AI Expo Africa · 28–29 October · Sandton Convention Centre, Johannesburg. Africa's biggest AI and smart automation trade show.
THE LIST
4 Deals to consider this week
Item | Where | Price |
|---|---|---|
Bluetti EB70 portable power station | Amazon | R4,999.99 |
Switched 4-way multi-plug with surge protection | Makro | R99 |
Anker 20,000mAh power bank | Makro | R839 |
Solar LED camping light, USB rechargeable | Takealot | R330 |
The multi-plug is now unfortunately pink (probs why it’s marked down so much) if you have the stomach (or some paint) for it. And the biggest saving is R348 off the solar camping light at Takealot.
