Storm damage and control boards

4.1.1 Why this is a local subject

North-east Florida records roughly 68 thunderstorm days in an average year, which is a working figure rather than a headline: it means the supply to a house here is disturbed on something like one day in five through the summer. On top of that sit the named events. St. Johns County lost power for days in places after Matthew in 2016 and Irma in 2017, and again after Helene in 2024.

A modern cooking suite is mostly electronics. A wall oven has a control board and usually a relay board. An induction cooktop has an inverter for each coil group. A gas rangetop has a spark module. A hood may have a speed control and a damper interlock. Those parts cost more than the mechanical components around them, and they are the ones a disturbance on the supply reaches first.

4.1.2 Damage is usually partial

The mental model most owners have is that a surge either destroys an appliance or it does not. In practice the common outcome is a component that survives with less margin than it had — a stressed capacitor, a semiconductor junction that has been through more energy than it was designed for, a solder joint that has been heated hard once.

The appliance then works. It works for a week, or a month, or a season, and then it fails on an ordinary evening with clear skies, which is why almost nobody connects the failure with the storm that caused it. If an appliance changed behaviour on the afternoon of a storm and never quite recovered, tell us. It changes what we look at first.

4.1.3 Outages are two events, not one

The loss of supply is the harmless half. The return is where the damage tends to happen: everything in the house that was switched on at the moment of the outage restarts at the same instant, and equipment on a partially restored network can see voltage well away from nominal while that settles.

The practical advice is the boring kind. During a prolonged outage, switch large appliances off at the breaker rather than leaving them to come back by themselves, and bring them back one at a time once the supply has been stable for a while. It costs nothing and it removes the worst moment from the equation.

4.1.4 What we check, in order

Supply first, always. Both legs of a 240-volt feed measured under load rather than at rest, the breaker itself — breakers age, and one that has tripped repeatedly can trip early or hold badly — and the connections in the box behind the appliance, which loosen with thermal cycling and read as an intermittent fault long before they read as a dead one.

Protective devices next. Thermal cutouts and fuses exist to open, and an open one is a symptom rather than a diagnosis; the question is always what made it open, and refitting one without answering that is how the same repair happens twice.

Then the low-voltage side: harnesses, connectors and the ribbon between a display and its board, all of which suffer from heat and vibration and none of which cost what a board costs.

The control board is last on the list. It is the most expensive part in most of these appliances and, in the calls we take, the least often the actual answer.

4.1.5 Protection is an electrician’s job

Whole-house surge protection is fitted at the panel and it is the only measure that covers a hard-wired appliance, since a built-in oven has no plug to put a strip on. We do not sell or install it. We mention it because we see the consequences of not having it every summer, and because the arithmetic is not close: the protection costs less than one control board for one appliance.

Point-of-use protection still helps for anything that does plug in, and it has a service life — a device that has taken a large event has done its job and should be replaced rather than trusted indefinitely.

4.1.6 When to call the manufacturer instead

If the appliance is still inside the manufacturer’s warranty, take the fault to the manufacturer’s own service channel first. That work is theirs to do and it costs you nothing.

Where a homeowner’s insurance claim is involved, ask what documentation the insurer wants before any parts are changed. A written diagnostic that records what was measured is usually acceptable; an appliance already stripped and repaired is a harder claim to make.