Load-shedding doesn't just cut your power — every switching cycle sends transient surges into your board that quietly kill electronics. Here's the fix.
title: "Load-shedding switching surges: why electronics die" description: "Load-shedding doesn't just cut your power — every switching cycle sends transient surges into your board that quietly kill electronics. Here's the fix." date: "2026-06-11" author: "EBB South Africa" tags: ["load-shedding", "surge protection", "Type 2 SPD", "South Africa", "SANS 61643"] draft: false
If you run electronics anywhere in South Africa, you already know the routine: the lights drop, you wait out the stage, and a couple of hours later everything comes back on. What most people never see is what happens in the milliseconds around each of those switching events. That invisible moment is where a surprising amount of equipment quietly dies.
Surge damage from load-shedding rarely looks dramatic. There's no bang and no smoke. A geyser element fails a week early, a TV stops waking from standby, a variable-speed drive throws an over-voltage fault, an inverter's control board goes dark. Each gets written off as "it was old" or "bad luck". In aggregate, across millions of switching cycles a year, it's neither — it's a predictable electrical phenomenon called a switching transient, and it is exactly what a Type 2 surge protective device (SPD) is built to stop.
What actually happens when the power switches
We tend to picture load-shedding as a clean on/off. Electrically, it's anything but. When a large load is connected or disconnected — a substation feeder re-energising a suburb, a generator transfer switch closing, a big motor or transformer dropping out — the current can't change instantly. The energy stored in the inductance of the cabling and the connected equipment has to go somewhere, and it does so as a fast, short-lived voltage spike riding on top of your normal 230 V supply.
These spikes are called switching transients (or switching overvoltages). They are typically much shorter than a lightning surge (microseconds rather than the longer impulse of a direct strike) but they happen far more often. A single thunderstorm might hit your area a handful of times a season. Load-shedding, by contrast, can subject the same distribution board to switching events twice a day, every day, for months. It's not the size of any one transient that wears equipment out — it's the relentless repetition.
Two things make the South African situation worse than a stable grid:
- Repeated re-energisation. Every time a feeder comes back, the inrush as transformers, motors and capacitive loads all wake at once produces a transient. More stages means more cycles means more transients.
- Backup-source switching. Homes and businesses now run inverters, UPS units and generators. The transfer between grid and backup, and back again, is itself a switching event, often closer to your sensitive electronics than the utility's switching ever was.
Why electronics are the first to fail
Modern electronics are efficient because they run on tightly regulated low-voltage rails — 3.3 V, 5 V, 12 V — derived from the mains by a switch-mode power supply. Those supplies, and the semiconductors behind them, have a hard ceiling on the voltage they can survive. A transient that's harmless to a kettle element can punch straight through the insulation of a control IC or the input stage of a power supply.
The damage comes in two flavours. Sometimes a large transient kills a device outright. Far more often, a smaller transient does cumulative damage: each spike degrades the silicon and the supply's input components a little more, until one ordinary switching event finally finishes the job weeks later. That delay is exactly why the cause is so easily missed: the failure rarely lines up with a memorable event.
The equipment most exposed is the equipment South Africans have bought because of load-shedding: inverters, battery management systems, solar charge controllers and the smart loads connected to them. The irony is sharp: the kit installed to ride out load-shedding sits right in the firing line of the transients that load-shedding generates.
How a Type 2 SPD protects the board
A surge protective device works by doing nothing almost all the time, then acting in a fraction of a microsecond when it matters. Under normal voltage it's effectively invisible to the circuit. The instant a transient pushes the voltage past a set threshold, the SPD's metal-oxide varistor becomes conductive and diverts the surge energy to earth, clamping the voltage that reaches everything downstream to a safe level. When the transient passes, it returns to its standby state.
For switching transients on a distribution board, the right tool is a Type 2 SPD. The classes matter, so it's worth being precise:
- Type 1 (Class I) devices are tested against the direct-strike lightning waveform (the longer 10/350 µs impulse) and belong at a building's main entry where a lightning protection system is installed.
- Type 2 (Class II) devices are tested against the induced-surge and switching-transient waveform (the 8/20 µs wave) and are rated by their nominal discharge current (In) and maximum discharge current (Imax). This is the class that lives on your distribution boards and handles the day-to-day switching events from load-shedding.
EBB's certified Type 2 device for South African boards is the PZ-C 275/40. It's a single-pole, 18 mm DIN-rail module with a continuous operating voltage (Uc) of 275 V (matched to standard SA 230 V single-phase supplies), a 20 kA nominal discharge current, a 40 kA maximum discharge current, and a voltage protection level (Up) of ≤1.2 kV. In plain terms: it sits quietly on your board, and when a switching transient arrives it clamps the let-through voltage low enough that your electronics never see the spike that would have shortened their life.
If the jargon on the marking plate is unfamiliar, our number decoder breaks down every symbol (what Uc, In, Imax and Up actually mean) in plain English.
Practical guidance for contractors
A few field notes for electricians and panel builders specifying protection on load-shedding-prone installations:
- Protect each phase. A Type 2 SPD like the PZ-C 275/40 is per-phase. On a single-phase board that's one module on the live; on three-phase, fit one per phase. The remote-signalling variant (PZ-C 275/40R) adds a dry contact so end-of-life status can be reported to a BMS or alarm panel.
- Coordinate, don't substitute. A Type 2 device protects against induced and switching surges, not direct strikes. Where a structure has a lightning protection system, a Type 1 (or Type 1+2) device belongs at the main entry, with the Type 2 downstream. The two classes work together. They aren't interchangeable.
- Install per the wiring code. SANS 10142-1 governs where and how SPDs are fitted on South African boards. Keep connecting leads short and straight: every extra centimetre of conductor adds inductance that raises the voltage your equipment actually sees, undoing part of the SPD's job.
- Plan for end-of-life. Varistors wear down with every surge they absorb — that's the device doing its job. EBB's modular range lets you swap the worn cartridge (the PZ-C 275/40 MODULE) without rewiring, so a board protected today stays protected after a heavy storm season.
- Quote the compliance, not just the part. Specifying for a tender or a QA file means proving the device is legal to sell and fit in South Africa. EBB's PZ-C 275/40 family is covered by NRCS Letter of Authority ZAF-RCC-0029482 under VC 8055 and tested to SANS 61643-11. The documents are downloadable on our compliance page, not "available on request".
The bottom line
Load-shedding's real cost isn't only the hours without power — it's the slow attrition of the electronics on the other side of every switching event. The transients are invisible, repetitive and cumulative, which is exactly why the damage gets blamed on age or bad luck instead of the grid. A correctly specified, NRCS-certified Type 2 SPD on the distribution board is the single most cost-effective defence: a quiet module that pays for itself the first time it clamps a spike your inverter would otherwise have taken on the chin.
If you're a contractor or wholesaler specifying protection for South African conditions, get in touch through our onboarding form and we'll match the right certified device to your installation.