Why did my electronics get damaged in a storm even with a surge protector?

Most of the time, electronics are damaged despite a surge protector because the surge did not come through the path the protector guards, or because the event was bigger than any typical protector can handle. A spent protector, weak grounding, or a device plugged in on another circuit explain most of the rest. Working out which one happened tells you what to fix before the next storm.

The surge came in on another wire

A power strip only watches the power cord. The National Weather Service explains that lightning can enter a structure by a direct strike, through wires or pipes that extend outside it, or through the ground,^[2] and once inside it can travel through the electrical, phone, plumbing, and radio and television reception systems.^[2]

NIST's homeowner guide makes the same point about appliances: each of the power, telephone, cable and antenna connections offers a path for a surge to come in, something that might be overlooked when the cause of damage is explained as a power surge.^[1]

Devices with two connections are hit hardest. NIST says a surge coming in on either system can damage the appliance because of the difference in voltage between the two, and that this can happen even when there are surge protectors on each system.^[1] It adds that insurance company statistics put video systems and computers with a modem connection at the top of the list of appliances most often damaged during a lightning storm.^[1] A TV on cable, a modem and router, or a computer on a wired network are the usual casualties.

The fix NIST describes is a combined protector that carries both the power and the phone or cable line through the same box,^[1] like the one in the photo above, with coax and phone jacks beside the outlets.

The strike was too close

There is a limit to what any protector can do. The National Weather Service says: "Lightning generates electric surges that can damage electronic equipment some distance from the actual strike. Typical surge protectors will not protect equipment from a lightning strike."^[2] NIST notes that even appliances with simple mechanical controls might be damaged in extreme cases, such as a direct strike to the building or one very close to the utility.^[1] If a tree, the house or the pole outside was hit, damage despite protection is not a sign the protector was faulty.

The protector was already spent

Surge protectors wear out as they absorb surges, and some fail quietly. NIST explains that some protectors cut off power when their protective element fails, while others disconnect the failed element and keep powering your equipment.^[1] With the second kind, everything keeps working with no protection left. On one APC model the user guide is plain: "If the LED is not illuminated the surge suppression circuitry has been compromised."^[3] Check the light on every strip, especially old ones behind furniture. Our answer on how long a surge protector lasts covers the signs.

The grounding or bonding is poor

NIST reminds readers that your surge protector works by diverting surges to ground, and the best surge protector can be useless if grounding is not done properly.^[1] One common problem is the separate services not being tied together: NIST says cable TV service that is not bonded to the power service ground is a clear violation of the National Electrical Code, but not so rare, and the result can be severe damage.^[1] For whole-house units, Siemens's installation notes say neutral-to-ground bonding not done to the NEC is the leading cause of surge device failures.^[4] These are things only an electrician should open up and check.

The device was on another circuit, or an ungrounded outlet

A protector in one room does little for another. NIST says a plug-in protector may help other receptacles on the same branch circuit, but that benefit is much less on other branch circuits.^[1] Each sensitive device needs its own.

The outlet matters too. NIST warns that some combined protectors might not work very well if plugged into a two-slot receptacle with a cheater plug,^[1] and APC's guide tells users to plug the unit into a 3 wire, 120 volt, grounded outlet.^[3] In an older Virginia house with two-prong outlets, that may be the whole story; see what replacing two-prong outlets involves.

It was not really a surge

Storms also bring downed lines and utility faults. NIST notes that most of the rare catastrophic failures of surge protectors are caused by excessively high line voltage that can occur when there is a fault on the power system.^[1] A longer rise in voltage is what NIST calls a swell, and it can damage appliances if it is a very large or very long swell.^[1] If many things failed at once and lights brightened or flickered, tell your power company as well as an electrician.

What to do after the storm

Wait it out first. The weather service warns: "Do not unplug equipment during a thunderstorm as there is a risk you could be struck."^[2]

Afterwards, look at every protector's lights. On the APC model, a Ground OK light that goes out signals a wiring fault, such as a missing ground, a hot-neutral polarity reversal or an overloaded neutral circuit, and the user should stop using the unit and have a qualified electrician correct the building wiring.^[3] Keep damaged equipment, the protector and receipts in case a connected equipment warranty applies.

When to call a licensed pro

Call right away if the panel or any outlet shows the warning signs CPSC lists: sizzling or buzzing sounds, parts that are hot to the touch or discolored from heat, and an odor of hot insulation.^[5] Call too if several devices failed at once, a protector reports a wiring fault, or you want a whole-house unit added. Virginia defines an electrician as a tradesman who does the construction, repair, maintenance, alteration or removal of electrical systems regulated under the building code,^[6] and no individual may work as a tradesman unless licensed.^[7] Ask the electrician to check the grounding and bonding of the power, cable and phone services, and whether a panel device makes sense; our answer on whether you need a whole-house surge protector helps with that.

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