Why the Granny Cable Is a Bad Long-Term Plan
Every EV ships with a portable cable that plugs into an ordinary socket. It works. Manufacturers include it for a reason. But it was designed as a get-you-home option, and using it every night for three years is a different proposition entirely.
The problem is duration rather than current. A kettle pulls a big load for four minutes. A car pulls 8 to 10 amps continuously for eight or ten hours, night after night. Socket outlets, their terminals and the wiring behind them were sized on the assumption that nothing does that. Where the connection is slightly loose or the contacts have aged, resistance turns into heat, and heat concentrates at exactly the point you cannot see.
We have opened up a scorched socket in a Garsfontein garage where the homeowner had been trickle charging off a twenty-year-old outlet on a shared circuit. The plug top had discoloured. Nothing had tripped, because nothing was faulty in a way earth leakage or a breaker would notice. It was simply running hot for longer than it was ever meant to.
If you are using a granny cable in the meantime
- Plug directly into a wall socket. Never through an extension lead, multi-plug or adaptor.
- Use the lowest current setting the car offers, usually 8A, and accept the slower charge.
- Feel the plug and the wall plate after an hour. Warm is tolerable. Hot means stop.
- Uncoil the cable fully. A coiled cable under continuous load traps its own heat.
- Do not run it under a closed garage door or across a wet driveway.
Charger Speeds, and Which One You Actually Need
Most people over-buy here. The right question is not how fast the charger can go, it is how many kilometres you drive in a day and how many hours the car sits at home.
| Output | Supply | Roughly adds | Suits |
|---|---|---|---|
| 2.3 kW (granny cable) | 10A socket | 10 to 15 km per hour | Emergencies and plug-in hybrids |
| 3.7 kW | 16A single phase | 20 km per hour | Plug-in hybrids, low-mileage drivers |
| 7.4 kW | 32A single phase | 40 km per hour | The right answer for most Pretoria households |
| 11 kW | 16A three phase | 60 km per hour | Three-phase homes, two EVs |
| 22 kW | 32A three phase | 120 km per hour | Rarely justified at home, and few cars accept it |
A 7.4 kW unit puts about 320 km back into the car over an eight-hour overnight window. The average Gauteng commute is nowhere near that. Unless you are running two electric cars or doing serious daily distance, paying for 22 kW buys you capability you will use twice a year, and it triples the demand on your supply.
One thing worth checking before you buy: your car's onboard AC charger sets the ceiling. Several popular models cap at 7.4 or 11 kW regardless of what you plug them into. A 22 kW wallbox feeding a car that accepts 7.4 kW charges at 7.4 kW.
Can Your House Actually Take It?
This is the part that determines your quote, and it is the part most online cost guides skip. A large number of Pretoria homes sit on a 60A single-phase supply. A 7.4 kW charger takes 32A of that on its own.
Add a 3 kW geyser element, an oven, a pool pump and a tumble dryer on a winter evening and you are past the limit. The main breaker or the municipal fuse decides the argument, usually at the least convenient moment.
Load management on the charger
The best-value fix. A charger with a current transformer clamped on the main incomer watches total household demand and throttles the car down when the rest of the house wakes up. Costs a few thousand rand more than a dumb unit and usually removes the need for a supply upgrade entirely.
Scheduled charging
Simplest option. Set the car or the charger to start at 22:00 when the geyser cycle is done and the house is quiet. Free, and it fits how most people actually use their cars.
Apply for a larger supply
Going from 60A to 80A, or to three phase, is a municipal application with its own cost and timeline through the City of Tshwane. Worth it if you were already tight before the car arrived. Not worth it purely for charging.
Shift the geyser instead
Often overlooked. Putting the geyser on a timer or a heat pump frees up meaningful capacity and lowers the bill at the same time. We look at this before recommending a supply upgrade.
The board itself
Beyond capacity, there is physical space. A charger circuit needs a breaker and dedicated earth leakage protection, which is two to four modules. Plenty of older Pretoria boards have nothing free. If yours still has rewireable fuses or no earth leakage at all, the charger is not the first problem to solve. Our DB board upgrade guide covers what that involves.
What SANS Requires, in Plain Terms
EV charging is covered under SANS 10142-1, with the current edition being 3.2, released in August 2024. Four requirements do most of the work.
A dedicated circuit, all the way back to the board
The charger gets its own way from the distribution board. It does not share with the garage plugs, the gate motor or the outside lights. Nothing else may be connected to it. This is non-negotiable and it is the first thing another electrician will look for.
Earth leakage protection that copes with DC
Vehicle electronics can put smooth DC residual current onto the supply, and DC leakage can desensitise an ordinary Type A or AC device so it fails to trip when you need it to. The circuit therefore needs either a Type B RCD, or a charger with certified 6 mA DC detection built in sitting behind a Type A device. Your existing house earth leakage unit does not satisfy this on its own, and 30 mA remains the residential trip threshold.
Cable sized for the run, not just the current
As a starting point, 6 mm² copper for 7.4 kW, 10 mm² for 11 kW and 16 mm² for 22 kW. Then the run length gets checked for voltage drop. On a Pretoria property where the board is in the kitchen and the parking bay is 35 metres down the side of the house, the calculation, not the table, decides the cable.
Earth continuity that has actually been tested
Verified continuity back to the main earth bar, measured and recorded, not assumed. On a metal-clad charger mounted on an outside wall this is what stands between a fault and the person holding the connector.
There is a fifth item that SANS does not force but Pretoria weather does. An EV charger is an expensive piece of electronics on an outside wall in one of the most lightning-prone regions on earth. Surge protection on that circuit is worth the R900. We wrote about Highveld surge protection separately.
And a COC at the end
Adding the circuit is an alteration to the installation, so a Certificate of Compliance is required. Keep it with your property file. If a fire ever starts anywhere near that circuit, the certificate is the first document your insurer will ask to see, and its absence is the easiest reason for them to decline.
What Installation Day Looks Like
A straightforward installation is a single day. Boards that need upgrading, or cable runs that have to go around a paved courtyard, push it to two.
Site visit and load assessment
Before any quote. We check your supply size, what is on the board, where the car parks, and how the cable will get there. You get a written quote with the cable route described, because that is where surprise costs hide.
Isolate and prepare the board
Power off, new breaker and dedicated earth leakage protection fitted, circuit labelled properly. If the board is full, this is where the upgrade happens.
Run and secure the cable
Conduit or trunking depending on the route, correctly clipped, with proper penetration sealing where it goes through a wall. We do not run cable across a roof void and hope.
Mount and commission the charger
Unit mounted at a sensible height for the charge port, connected, configured on your wifi if it is a smart unit, and load management set up where fitted.
Test everything, including the trip
Insulation resistance, earth continuity, polarity, and a real earth leakage trip test with a proper tester rather than the test button. Results recorded.
Charge the car, then hand over the COC
We do not leave until the car has actually taken charge. You get the certificate, the test results and a walkthrough of the app.
On mounting height, a small detail that saves daily irritation: match it to where the charge port sits on your car and which way you reverse in. A charger mounted at head height on the wrong side of a double garage means dragging the cable around the bonnet every night for the next five years.
2026 Costs, Itemised
Pretoria and Centurion ranges for 2026. Hardware prices move with the exchange rate, so treat those as indicative and the labour lines as ours.
| Item | 2026 range | When it applies |
|---|---|---|
| 7.4 kW smart charger | R12,000 to R18,000 | The sensible choice for most homes |
| 11 kW three-phase charger | R18,000 to R28,000 | Three-phase supply, or two EVs |
| Standard installation | R6,500 to R11,000 | Board within about 15 m of the bay |
| Long or difficult cable run | R11,000 to R15,000 | Over 20 m, trenching, or paving to lift |
| Type B RCD or DC-capable protection | R2,200 to R4,500 | Where the charger has no built-in 6 mA detection |
| DB board upgrade | R4,500 to R8,500 | No space, or no earth leakage on the board |
| Surge protection on the circuit | R900 to R2,500 | Recommended on every Pretoria installation |
| Certificate of Compliance | Included | Part of our installation price |
A typical Garsfontein or Faerie Glen house with a reasonably modern board and the garage close to the DB lands around R20,000 to R28,000 all in, charger included. An older property in Pretoria North where the board needs replacing and the cable has to travel 30 metres can reach R38,000.
Be wary of a quote under R5,000 for installation. At that price something is being left out, and it is usually the dedicated DC-capable protection or the correct cable size. Both are invisible until they matter.
Charging From Solar
Plenty of Pretoria households arrive at an EV having already installed solar, and the combination is genuinely good. Tshwane gets a lot of sun, and a car parked at home during the day is a large, flexible battery you were going to charge anyway.
Two practical points. First, a 7.4 kW charger will happily consume everything a 6 kW array produces and then start pulling from the grid or your house battery, which is rarely what you want. Chargers with solar-tracking or surplus-only modes solve this by following what the array is actually exporting. Say so up front, because it changes which unit we recommend.
Second, adding a charger to a solar property means a new COC covering the whole installation, and if your system is registered as embedded generation, the load change is worth flagging. If you are unsure whether your solar was ever properly registered, our guide to solar COC and SSEG registration in Pretoria walks through how to check and how to fix it.
Charging during load shedding
Most hybrid inverters can run a charger off battery, but a 7.4 kW draw will empty a 10 kWh battery in under ninety minutes and leave you with no lights. If you want the car on the essential loads side, it needs to be on a controllable circuit, and honestly, for most households it should not be. Charge overnight instead. Our load shedding solutions guide covers sizing.
Complexes, Estates and Body Corporates
If you live in a townhouse complex in Centurion or an estate in Midstream, the charger is as much a governance question as an electrical one. The parking bay is often common property and the supply route almost always crosses it.
What gets applications approved, in our experience, is turning up with a document rather than a request. Trustees say no to vague ideas and yes to specifics.
Bring the trustees this
- A single-line diagram showing where the supply comes from and how it is metered to your unit
- Confirmation the electrician is registered with the Department of Employment and Labour
- The charger specification, including its current draw and any load management
- A written statement that a COC will be issued and a copy handed to the body corporate
- How the cable will be routed and made good, and who carries the cost if the bay is ever reallocated
Metering is the part that causes arguments later. If the charger is fed from common property supply, the complex pays for your fuel. A sub-meter or a feed taken from your own unit's supply settles it before anyone has to raise it at an AGM. We do this work regularly across Centurion and Midstream and can put the pack together for you.
Questions We Get Asked
Can the dealership install it?
Dealers usually subcontract to an electrical contractor. Ask who is actually doing the work, whether they are registered, and whether a COC is included in writing. The dealer is not the one signing the certificate.
Tethered cable or a socket?
A tethered unit is more convenient day to day. A socketed unit lets you use a different cable if you change cars and keeps the cable out of the weather. If the charger lives outside in Pretoria sun and summer storms, socketed ages better.
How much will it add to my bill?
At Tshwane residential tariffs, a full charge on a typical 60 kWh battery costs roughly R300 to R380 depending on your tariff block. That is around 350 to 400 km of driving.
Does it need its own earth spike?
No, and adding one incorrectly creates a hazard rather than removing one. The charger bonds to the existing installation earth. What matters is that the earthing arrangement is sound and tested, which is part of the COC.
Can I move it if I sell the house?
Physically yes, but the circuit stays and must be either safely terminated or left compliant. Most buyers want the charger left in place. Either way, the seller’s COC has to reflect the installation as it actually stands on transfer.
How long does the installation take?
A straightforward job is four to six hours. Add a day if the board is being replaced or if cable has to be trenched under a driveway.
Do I need permission from Tshwane?
No SSEG-style registration is required for a charger, since it consumes rather than generates. If the added load pushes you past your supply capacity and you need a bigger connection, that is a municipal application.
What about a bakkie or a fleet vehicle?
Larger battery, same principles, longer charge. For two or more vehicles at one property we generally look at three phase and load-shared chargers rather than two independent 7.4 kW units competing for the same supply.
Start With the Load Assessment
Almost every EV charger problem we get called out to fix traces back to a quote given over the phone without anyone looking at the board. Supply size, board capacity and cable route decide the price. Nobody can know those from a WhatsApp message.
We install home EV chargers across Pretoria, Centurion, Midrand and Sandton, on a dedicated circuit with proper DC-capable earth leakage protection and a Certificate of Compliance in your hand at the end. If your board needs work first, we will say so before you buy the charger rather than after.
Call 072 681 4615 or book a site visit. Tell us the car and where it parks and we can give you a realistic range before we arrive.
Written by Andre
Registered Electrician & Founder of INC Unlimited Pty. Ltd
With over 30 years of experience in the electrical trade across Pretoria and Gauteng, Andre and the INC Unlimited team have completed over 500 COC inspections, installations, and electrical projects. SANS 10142 compliant. Based in Equestria, Pretoria.