How Load-shedding Affects Your Geyser
What's actually happening inside the tank, and how to stop it costing you an element.
Load-shedding can wreck your geyser element without any obvious warning sign, and it's the callout we field most often at Pretoria East Plumbers across Pretoria East homes.
The moment the power comes back on is often riskier than the outage itself. Here's what's happening inside your geyser during an outage, and what to do about it.
What actually happens inside your geyser during load-shedding
Your geyser's element just stops when the power cuts.
The tank keeps losing heat slowly while the power's out. That part's harmless on its own.
The problem starts if hot water gets drawn from the tank during the outage, for a shower or dishes. As the tank empties and refills with cold water, the element can end up partially or fully exposed to air instead of water.
When the power comes back, that element switches straight back on. An element heating against air rather than water is what burns it out. It's a specific, mechanical failure mode, and it's one reason geyser issues cluster so heavily around load-shedding periods.
Geysers commonly account for up to 40% of a household's total electricity use. That's why geyser behaviour matters so much to both Eskom's load-shedding math and your own bill.
Why the power coming back on is often riskier than the outage itself
Two separate risks show up right at the moment your power returns, and they're often confused with each other.
The first is comeback load. When power comes back to a neighbourhood, every geyser that was off switches on at once to reheat. It's a documented, named phenomenon.
In a Project Smart Geyser pilot run by Plentify with the City of Cape Town and Hessequa Municipality (funded by GIZ/EEP Africa and verified by UCT), this synchronised reheating pushed peak geyser energy use up by as much as 90% in some areas, and cost affected households roughly R1,300 per geyser per year extra under some tariffs. That pilot measured Cape Town and Hessequa specifically. The same mechanism applies anywhere geysers share a grid with scheduled outages, Pretoria East included.
The second risk is voltage surges. Older installations without surge protection are especially exposed to spikes when supply resumes.
This can damage thermostats and wiring on its own, separately from the element-exposure problem above. Two different faults, one moment.
Which Pretoria East load-shedding group are you in, and does it matter?
Yes, and more than most homeowners assume.
City of Tshwane runs named load-shedding groups down to suburb and extension level.
Faerie Glen sits in Group 2, for example, while Moreleta Park is split across Groups 7 and 8. Two houses a few streets apart can be on completely different schedules.
Knowing your group matters for exactly the mitigation steps below: you can plan around a scheduled outage far more effectively than an unplanned one. Check your specific group and current schedule directly on the City of Tshwane's official load-shedding page.
What to do before, during, and after an outage to protect your geyser
A few habits make the real difference here:
- Before a scheduled outage: if you know load-shedding is coming, avoid running a bath or big load of hot water right before it starts. A fuller, hotter tank going into the outage means less chance of the element being exposed by the time power cuts.
- During the outage: avoid drawing hot water if you can. This is the single biggest factor in whether the element ends up exposed to air.
- When power returns: if your home doesn't already have surge protection on the geyser circuit, this is worth having a plumber or electrician install, particularly for older installations.
- For repeat comeback-load spikes: ask a plumber or electrician about a geyser load control timer. It's one of the smart-device options built around managing this kind of demand spike, worth discussing based on your specific setup.
They're low-cost habits and one-off protective steps, well short of replacing the geyser.
The compliance and insurance angle most homeowners don't know about
This is the part that catches people out after the damage is already done.
If a geyser fails and causes water damage, insurers commonly send an assessor before paying out. That assessor checks first for SANS 10254 compliance and a valid Certificate of Compliance (COC). A non-compliant installation is grounds for the claim being rejected outright.
Here's the nuance: as of 24 June 2022, the legal requirement for a COC specifically on electric geyser installations was removed from SANS 10254. COCs are still legally mandatory for solar geysers and heat pumps, just not standard electric ones anymore.
The Plumbing Industry Registration Board (PIRB) and IOPSA still recommend issuing and auditing COCs regardless. In practice, insurers and municipalities still routinely ask for them too.
When it's a load-shedding symptom, and when it's time to call a plumber
A geyser that's stopped heating properly right after a run of outages is very likely the element-exposure problem described above. That's a targeted, known fix.
A geyser that's leaking, tripping the breaker repeatedly, or making banging or popping noises is a different problem, separate from the element-exposure pattern described above. That's worth a plumber's assessment.
If you're not sure which one you're looking at, that's worth a call to a plumber. Our geyser installation and repair page has more on what to expect.
Load-shedding and Geysers — Common Questions
Does load-shedding damage geysers?
Yes. If hot water is drawn from the tank during an outage, the element can end up exposed to air, and reheating against air rather than water once power returns is what burns it out.
Does switching off the geyser during load-shedding help protect it?
Yes, turning the geyser off at the breaker before or during a scheduled outage removes the exact risk described above, an element left exposed to air as the tank empties, and it costs nothing to do.
Does load-shedding damage other appliances too, not just the geyser?
Yes, voltage surges when power is restored can damage thermostats and wiring in older installations without surge protection, a separate risk from the element-exposure issue that specifically affects geysers.
What kind of damage does load-shedding actually cause to a geyser?
The main damage is a burned-out element from the exposure mechanism above, plus a secondary cost hit from comeback load, where a documented Cape Town area pilot recorded peak geyser energy use spiking by as much as 90% and costing households roughly R1,300 extra per geyser per year.
Does insurance cover geyser damage caused by load-shedding?
It depends on compliance. Insurers commonly send an assessor to check for SANS 10254 compliance and a valid Certificate of Compliance before paying out, and a non-compliant installation is grounds for the claim being rejected.
What is a geyser load control timer?
A geyser load control timer is a device built to help manage comeback load, the neighbourhood demand spike that hit as much as 90% in one documented pilot. Ask a local plumber or electrician whether it's a fit for your installation.