How Do I Know if My Surge Protector Is Still Working?

Look at the indicator. Almost every surge protector made in the last two decades, whether it sits at your panel or under your desk, has a light that tells you whether it is still protecting anything. The catch is that a dead protector keeps passing power normally, so nothing about the outlet or the lights will tell you it has stopped doing its job.

That happens two ways. A single large event, a nearby lightning strike or a utility fault, can finish one instantly. More often it is gradual: the small surges that come from motors starting and stopping inside your own house, and from switching out on the network, each take a little of the protector’s capacity until there is none left.

When it is spent, the protection ends but the power does not. Devices plugged into it still run. The lights on that circuit still work. This is the part people find surprising, and it is why the indicator exists.

So the answer is: check the light. On a whole-house unit at the panel it is usually a small green LED, sometimes with an audible alarm. On a plug-in strip it is normally marked “protected” and sits next to the power light, which is a different light entirely and is not the one to read.

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What is usually causing it

If the indicator has changed, something used up the protector. The useful question is what.

What you see	What it means	What to do
Green or “protected” lit	Still working	Nothing
Indicator off, power still on	Protection spent, device still passing power	Replace
Red, amber, or an audible alarm	End of life, varies by maker	Read the legend, then replace
Scorching, discolouration or a smell	A serious event, or a failure	Stop using the circuit, call an electrician
No indicator at all	Older or basic unit, condition unknown	Treat as unknown and have it assessed

After a storm or a known event

If you had a strike nearby, a utility outage with a hard return, or several devices in the house died at once, check the indicator afterwards rather than assuming. That is exactly the kind of event a protector is bought for, and exactly the kind that ends one.

The quiet kind of wear

Most protectors do not die dramatically. Compressor motors, well pumps, furnace blowers and air conditioning all put small spikes onto your wiring every time they start, and a protector takes a little damage from each. A house with a lot of motor load consumes protectors faster than a quiet one, with nothing visible happening along the way.

Grounding decides whether it works at all

This is the part that gets missed. A surge protector works by diverting excess energy to ground. If the grounding and bonding at the service are poor, corroded, or were never right, the path the protector needs is compromised. It can still clamp between the line and neutral, but the diversion to ground that handles the largest events is the part that suffers, and the device will show a healthy green light either way.

That is why a competent installation checks the grounding first rather than simply fitting the device.

What is safe to check yourself, and what is not

Safe, and worth doing twice a year: reading the indicator on the panel-mounted unit, reading the “protected” light on plug-in strips, noting the age of anything plugged in, and checking again after any significant electrical event. Reading the label on the unit to find out what its indicator colours mean is also a homeowner task, and the legends differ between manufacturers.

Not a homeowner job: anything involving the panel. A whole-house protector is wired into the service equipment, and even with the main breaker off the service conductors and the main breaker’s line-side lugs stay live until the utility disconnects them. Fitting, replacing or inspecting one is licensed work carried out under a permit from the municipality. In Milwaukee, Wauwatosa and across Waukesha County that falls under Wisconsin SPS 316, which adopts the 2023 NEC and took effect on September 1, 2026.

If a protector, outlet or panel is discoloured, scorched, buzzing, or smells of hot plastic, stop using that circuit and call. Do not judge it by touch.

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When it points to a bigger problem

A protector that has quietly expired is routine. A pattern is not.

Protectors that keep failing. If you are on your second or third in a few years, something is producing more surges than a typical house. That can be the utility supply, equipment inside the house cycling hard, or a loose connection generating disturbances of its own. Replacing the protector again treats the symptom.

Electronics dying in clusters. Several devices failing in a short span, especially after storms, suggests either that the protection is already gone or that it was never adequate for what arrives. Smoke alarms are worth including in that count, since they contain electronics too and a run of early failures is a signal. A detector behaving oddly has its own explanations, covered in a smoke detector’s green light.

Nuisance tripping alongside it. A surge can trip a GFCI or AFCI device outright, and repeated tripping afterwards can reflect damage the surge left behind rather than a new fault. A circuit that starts tripping around the time the protector changed state is worth looking at as one problem rather than two. What trips a GFCI outlet covers the overlapping causes.

No protection at the panel at all. Plug-in strips handle small local spikes near a device. They are not designed for what arrives from outside, and a house relying only on strips is only partly covered.

What an electrician does about it

The work begins with the ground, not the device. An electrician checks the grounding electrode system and the bonding at the service, because a protector on a poor ground is decoration. Where the grounding needs attention, that comes first.

Then the existing protection gets assessed: what is fitted, what its indicator says, whether it is sized sensibly for the service, and whether it has simply reached the end of its life. Replacement is usually a short visit once the panel is accessible and there is breaker space, carried out with the cover off and the circuit isolated, then verified before the panel is closed.

Where protectors have been failing repeatedly, the conversation widens. That means looking at what inside the house generates surges, whether connections at the panel are sound, and whether the problem is arriving from the utility side, which is coordinated with them rather than worked on directly.

Lehmann Electrical & Design is led by master electrician Jacob Lehmann and works across Milwaukee, Wauwatosa and Waukesha County from 12012 W Fairview Ave, Wauwatosa. Work carries a 12-month workmanship warranty, and the company holds 4.9 stars on Google.

You can see what whole-house surge protection involves, or request an estimate and call 414-207-0109.

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