Maintenance procedure · Written to ASD-STE100 Issue 9 · Formatted to ANSI Z535

Check a Surge Protector and Know When It Is Spent

Plug-in surge protectors and surge-protecting power strips — the indicator lights, the label, and the day the strip becomes only a strip
ApplicabilityCord-connected and direct-plug surge protectors and surge-protecting power strips in a dwelling
Task time25 min to 59 min editorial estimate, not a measurement
PersonnelOne
Revisionv1 · 2026-08-06
BEFORE YOU BEGIN

Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.

Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.

Summary

A surge protector is the power strip you bought because the box said surge protector, and the thing almost nobody is told about it is that it does not stop working the way a light bulb stops working. The protective parts inside are consumable. They take the hit, they wear, and one day they are finished — and depending on how your particular unit was designed, the outlets may go on delivering power exactly as before. NIST's consumer guide says so plainly: some protectors cut the output power off completely when the protective element fails, and others disconnect the failed element and maintain the power output. You cannot see which of the two you own by looking at the outside, and your equipment will never tell you. What you can do is read the indicator lights, read the label, read the sheet that came in the box, and know what each of them is and is not saying.

This page covers the outside of the unit only. Nothing is opened, nothing is wired, and no meter is used. It will not print a joule rating, a service life in years or a replacement interval, because those belong to your model and to your own documentation — and where the sources disagree, as they do about how long a surge protector lasts, this page prints the disagreement instead of an average. If the ground light on your strip is dark, the page stops and sends you to a licensed electrician, because that light is reporting on the outlet in your wall rather than on the strip. Protection for a whole building is not covered here. What you get is a repeatable check you can run on every strip in the house in one pass, and an answer to the only question that matters: is this thing still protecting anything?

Safety

WARNING

NEVER OPEN THE HOUSING OF A SURGE PROTECTOR.
The parts in the housing can cause a fatal electric shock.

Necessary equipment

ItemNote
The instruction sheet that came with the surge protectorThe instruction sheet gives the meaning of each indicator.
Notebook or maintenance recordRecord the model number and the result of each check.
Flashlight optionalSome receptacles are in a dark space.
Camera or phone optionalA photograph of the label keeps the model number.

Find the surge protectors

Estimated 5 min to 16 min

NOTEA power strip is not always a surge protector.
  1. Find each power strip in the building.
    • Examine the space below a desk, behind a television and behind a bed.
    • Record the position of each unit.
    4m
WARNING

DO NOT USE A SURGE PROTECTOR THAT HAS DAMAGE, MARKS FROM HEAT OR A SMELL OF BURNT PLASTIC.
A fire can occur.

  1. Read the words on the housing of each unit.
    • A unit with the words surge protector on the housing has protective parts in it.
    • A unit without these words is only a power strip and gives no protection.
    <1m
  2. Examine the housing, the cord and the plug of the unit.
    • Damage, marks from heat and a smell of burnt plastic are conditions to refuse the unit.
    • Replace a unit that has damage.
    <1m

Read the label and the instruction sheet

Estimated 5 min to 9 min

NOTEThe label gives the model number and the surge energy rating.
Surge energy rating of your unit
Unverified — do not rely on this value
READ THE JOULE RATING FROM THE LABEL ON THE UNIT

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. Read the label on the bottom of the unit.
    • The label gives the model number.
    • The label usually gives the surge energy rating in joules.
    • The label gives the mark of the laboratory that listed the unit.
    1m
  2. Record the model number of the unit.
    • A photograph of the label is sufficient.
    <1m
  3. Record the surge energy rating from the label.
    • The surge energy rating is a measure of the energy the unit can dissipate.
    • Some units do not give this rating on the label.
    • The rating is a property of your model only.
    <1m
  4. Read the instruction sheet for the unit.
    • The instruction sheet gives the meaning of each indicator.
    • Indicator colors and indicator meanings are not the same for each manufacturer.
    • If you do not have the instruction sheet, get it from the website of the manufacturer.
    3m

Examine the indicators

Estimated 3 min to 7 min

Meaning of each indicator on your unit
Unverified — do not rely on this value
READ THE INSTRUCTION SHEET FOR YOUR UNIT. INDICATOR MEANINGS ARE NOT STANDARDIZED BETWEEN MANUFACTURERS.

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

WARNING

DO NOT USE A SURGE PROTECTOR IN A WET LOCATION.
Water and electrical power together can cause a fatal electric shock.

NOTICE

CONNECT THE SURGE PROTECTOR DIRECTLY TO A WALL RECEPTACLE.
A connection through a second cord can decrease the protection.

  1. Connect the unit directly to a wall receptacle.
    • A dry indoor location is necessary.
    <1m
  2. Set the switch of the unit to ON.
    <1m
WARNING

IF THE GROUND INDICATOR IS OFF, DO NOT USE THE SURGE PROTECTOR.
The receptacle can have a wiring fault that causes an electric shock.

  1. Examine the ground indicator.
    • The ground indicator must be on.
    • A ground indicator that is off shows a possible fault in the receptacle.
    • A surge protector sends the surge to ground and needs a correct ground connection.
    <1m
  2. If the ground indicator is off, speak to a licensed electrician.
    • A bad ground, an absent ground and reversed wiring are the usual causes.
    • Do not use the unit before an electrician corrects the receptacle.
    1m
  3. Examine the protection indicator.
    • The protection indicator must be on.
    • A protection indicator that is off shows that the protective parts are not serviceable.
    <1m
  4. If the protection indicator is off, push the circuit breaker button of the unit.
    • An overload can also cause a dark protection indicator.
    • The circuit breaker button is on the housing or in the switch.
    <1m
  5. Examine the protection indicator again.
    <1m

Decide if the unit gives protection

Estimated 3 min to 6 min

NOTEA unit that gives no protection continues to supply electrical power.
What your unit does when its protective element fails
Unverified — do not rely on this value
CONSULT THE MANUFACTURER DOCUMENTATION FOR YOUR MODEL

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Service life of a surge protector
Unverified — do not rely on this value
CONSULT THE MANUFACTURER DOCUMENTATION FOR YOUR MODEL

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Two named sources answer this differently and this page publishes neither as a value. CyberPower's own article says that each surge permanently destroys some of the joules the unit can absorb and that surge protectors generally last three to five years. NIST's consumer guide answers the same question by saying that electronic components age and have a limited life, but that the prevailing opinion among surge-protection specialists is that the rare catastrophic failures come mostly from an abnormally high supply voltage during a fault on the power system rather than from large surges. The two sources are not the same weight either: the NIST guide is a government publication from 2001 and is old enough that nothing here is published as verified on it, and the CyberPower article is a manufacturer blog post from 2022 and is registered at tier 2. Nothing is averaged. Read the documentation for your own model and, where it is silent, ask the manufacturer.
The electrical load your unit accepts
Unverified — do not rely on this value
READ THE LABEL ON THE UNIT AND THE MANUFACTURER DOCUMENTATION

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. If the protection indicator is not on after the reset, the unit gives no protection.
    • The outlets of the unit can continue to supply electrical power.
    • Electrical power at the outlets is not evidence of protection.
    <1m
  2. If the unit has no indicator, read the manufacturer documentation.
    • The manufacturer documentation gives the method to know the condition of the protection.
    • If the documentation gives no method, speak to the manufacturer.
    2m
WARNING

DO NOT PUT AN OVERLOAD ON THE SURGE PROTECTOR.
An overload can cause a fire.

  1. Count the equipment that you connect to the unit.
    • The manufacturer documentation gives the electrical load that the unit accepts.
    • Do not connect one surge protector to a second surge protector.
    1m

Replace a spent unit

Estimated 7 min to 19 min

Certification mark to look for on a replacement
Manufacturer or standard verified
A LISTING MARK FROM A NATIONALLY RECOGNIZED TESTING LABORATORY, SUCH AS UL, ETL OR CSA

Source: Safety at Home: Extension Cords (NSN-18-062021) · tier 1 · accessed 2026-08-06

NOTICE

STOP THE EQUIPMENT BEFORE YOU DISCONNECT IT FROM THE SURGE PROTECTOR.
A loss of data can occur.

  1. Disconnect the equipment from a unit that gives no protection.
    1m
WARNING

HOLD THE BODY OF THE PLUG WHEN YOU DISCONNECT THE UNIT FROM THE RECEPTACLE.
Damage to the cord can cause an electric shock.

  1. Disconnect the unit from the receptacle.
    <1m
  2. Get a replacement unit that has a certification mark.
    • A certification mark shows that a laboratory examined the unit.
    • UL, ETL and CSA are examples of these laboratories.
    • Do not use a unit that has no certification mark.
    5m
  3. Discard the spent unit.
    • Do not give a spent surge protector to a different person.
    <1m

Keep a record

Estimated 2 min

  1. Record the date of the check and the condition of each indicator.
    1m
  2. Do a check of the indicators again after an electrical storm.
    <1m
  3. Do a check of the indicators again after a loss of electrical power in the building.
    <1m

Terminology

This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.

surge protector
Also called: surge suppressor, surge protector power strip, surge strip, surge bar, surge board, spike protector, spike buster, power surge protector, power strip with surge protection, surge protected power strip
protection indicator
Also called: protected light, protection working light, protection present LED, surge light, diagnostic LED, green light on the surge protector, little green light
ground indicator
Also called: grounded light, ground light, not grounded light, earth light, red light on the surge protector
surge energy rating
Also called: joule rating, joules, how many joules, surge rating, energy absorption rating
power strip
Also called: outlet strip, power bar, extension block, multi plug, trailing socket, plug board
receptacle
Also called: outlet, wall socket, plug socket, power point, plug in the wall
surge protective device
Also called: whole house surge protector, SPD, surge arrester, lightning arrestor

When to use a professional

Stop if the ground indicator is off. Stop if the receptacle has damage or has marks from heat. Stop if the surge protector has a smell of burnt plastic. Speak to a licensed electrician.

Never open the housing of a surge protector. Never remove the cover plate of a receptacle. Never open the service panel. This page does not give a method to repair a surge protector. Replace a spent surge protector. Do not repair it.

Surge protection for a full building is not in this page. A licensed electrician installs that equipment. Speak to a licensed electrician about protection for a full building.

Common questions

How long does a surge protector last?

The published sources do not agree, and this page will not average them. CyberPower's own article says that each time a surge occurs the joules required to absorb it are permanently destroyed, and that surge protectors gradually lose protection and generally last three to five years. NIST's consumer guide answers the same question quite differently: many if not all electronic components age and have a limited life, but the prevailing opinion among surge-protection specialists is that most of the rare catastrophic failures come from an abnormally high supply voltage during a fault on the power system rather than from very large surges. The two are not equal weight either — one is a government guide from 2001, the other a manufacturer blog post from 2022 — and both are named in the sources so you can read them yourself. What survives the disagreement is the instruction both give: watch the indicator, and read the documentation for your own unit.

My surge protector still powers everything. Doesn't that mean it's fine?

No, and this is the most useful thing on this page. NIST's guide says most surge protectors contain some kind of internal fuse that disconnects on failure, but that the disconnect works in one of two ways depending on the design: some completely cut off the output power, others disconnect the failed element but maintain the power output. In the second case the strip goes on working as a strip, with nothing protecting anything plugged into it and no outward sign at all. NIST's own conclusion is that you have to know which of the two designs you bought. Eaton's datasheet for one Tripp Lite model states the first design in as many words — automatic shutoff permanently cuts power to the outlets if the protection circuit is incapacitated — which is the kind of sentence to look for in your own documentation.

What does the 'protected' light actually mean?

It means what your manufacturer says it means, and that is less of a dodge than it sounds. NIST's guide is blunt: manufacturers provide some form of indication, generally by pilot lights, but those indications are not standardized, the meaning can be confusing between one, two, three or four lights, and it is not always clear what a colour means. Its instruction is to read the instructions. CyberPower's support page says the surge light should be illuminated and that a light which is not lit means the unit took a severe surge and needs replacing. Eaton describes its own LED as confirming protection present. Three sensible wordings of the same idea, and no guarantee that your unit follows any of them — so read the sheet before you read the light.

The protected light is off. Do I throw it out?

Not on the first look. Belkin's user guide for one of its surge protectors gives the order to work in: an absent Protected light can mean the sockets are overloaded, so press the circuit-breaker button and reset the unit first, and if the light is still not on after that reset then the surge protector has reached the end of its useful life and should be replaced. Reset, look again, then decide. If it stays dark after a reset, the unit is a power strip now, whatever the housing says.

The ground light is off. Is the strip broken?

Probably not — that light is not reporting on the strip. CyberPower's support page says the ground indicator should be illuminated, and that if it is not there is an issue with the AC outlet that must be resolved before the surge protector is used; it names a bad ground, a missed ground and reversed wiring as the common causes and notes these are typical of housing built before 1980. It also says that using the suppressor with the ground light out will void the warranty. This matters more than the strip does: a surge protector works by diverting surges to ground, and NIST says the best surge protector in the world can be useless if grounding is not done properly. An unlit ground light is a call to a licensed electrician.

What is a joule rating, and what number should I buy?

NIST's guide describes joules as a simplified measure of the surge energy the protector can dissipate without damage to itself, gives typical values as running from about 100 joules up to 1000 joules or more, and adds that the published number is often a total across the three wiring combinations rather than a figure for each one. This page prints no target, because the right number depends on what you are protecting and because one number on a package is not a description of a device. Read the rating off the label of the unit you already own, write it down next to the model number, and keep the paperwork. Then the number means something the next time you compare two of them.

Is a power strip the same thing as a surge protector?

No. A power strip divides one outlet into several. A surge protector does that and also contains protective parts — and a surge protector whose protection is spent has quietly become the first thing. Read the housing and the label rather than the name on the packaging. Whatever you buy, check that it carries a listing mark from a Nationally Recognized Testing Laboratory: CPSC's advice on extension cords is blunt about it, telling you to check whether yours says it is listed by a laboratory such as UL, ETL or CSA, and that if it does not, you should not use it, because unlisted or counterfeit cords can cause fires or electrical shocks.

Are surge protectors ever recalled?

Yes, and it is worth a look while you have the model number in front of you. CPSC keeps a recall listing for this whole product category, cables and surge and power protection, and it is linked in the sources below. On the day this page was researched, 6 August 2026, that listing carried a single recall and it was for male-to-male extension cords rather than for a surge protector. This page therefore carries no recall entry, and that empty list is a finding rather than an omission — a snapshot printed here would be out of date within weeks, so search the listing yourself.

Sources

Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.

  1. Tier 1Surges Happen! How to Protect the Appliances in Your Home (NIST Special Publication 960-6)National Institute of Standards and Technology (U.S. Department of Commerce), author François D. Martzloff · accessed 2026-08-06 · re-verification due 2027-02-02
  2. Tier 1Protect It! 6-Outlet Surge Protector, 6 ft. Cord, 900 Joules, Diagnostic LED, Black Housing (model TLP606B)Eaton (Tripp Lite series) · accessed 2026-08-06 · re-verification due 2027-02-02
  3. Tier 1If my surge protector has a surge light, should it be illuminated?CyberPower Systems (USA), Inc. · accessed 2026-08-06 · re-verification due 2027-02-02
  4. Tier 1If my surge protector has a ground light, should it be illuminated (green)?CyberPower Systems (USA), Inc. · accessed 2026-08-06 · re-verification due 2027-02-02
  5. Tier 2Joules: The key to surge protectionCyberPower Systems (USA), Inc. · accessed 2026-08-06 · re-verification due 2027-02-02
  6. Tier 1Conserve Smart AV Auto-Off Surge Protector User Guide (F7C013uk)Belkin International, Inc. · accessed 2026-08-06 · re-verification due 2027-02-02
  7. Tier 1Safety at Home: Extension Cords (NSN-18-062021)U.S. Consumer Product Safety Commission · accessed 2026-08-06 · re-verification due 2027-02-02
  8. Tier 1Cables and Surge and Power Protection — Recalled ProductsU.S. Consumer Product Safety Commission · accessed 2026-08-06 · re-verification due 2027-02-02
  9. Tier 1Appliance and Electrical Fire SafetyU.S. Fire Administration (Federal Emergency Management Agency) · accessed 2026-07-29 · re-verification due 2027-01-25

Revision history

Current version 1 · updated 2026-08-06 · next review due 2027-08-06

  1. v1 · 2026-08-06First draft, from backlog candidate check-a-surge-protector-and-know-when-it-is-spent. Scope is the outside of the unit only: nothing is opened, no meter is used, and the professional boundary refuses the housing, the cover plate and the service panel. Rests on nine sources, all fetched and read on 2026-08-06 — NIST SP 960-6, an Eaton Tripp Lite datasheet, two CyberPower support FAQs, a Belkin user guide, a CPSC safety alert, the CPSC recall listing for this product category, USFA's electrical fire safety page, and one CyberPower blog post registered at tier 2 because it is marketing rather than service documentation. THE BRIEF'S PREMISE WAS CORRECTED BY THE SOURCES, and the correction is the page. The brief said a spent surge protector keeps supplying power; NIST says that is one of two designs, that the other cuts the output power off completely, and that the owner has to know which one they bought. The page publishes that split rather than the simpler claim, and the Eaton datasheet is cited as a named example of the cut-off design. No number is published: the joule rating, the service life, the load and the meaning of the indicators are all per-model and publish as instructions to consult the manufacturer. The service life carries a conflict_note because CyberPower says three to five years with joules consumed per surge and NIST attributes the rare catastrophic failures to high supply voltage instead; the two are named and nothing is averaged. The only verified specification is the certification mark to look for, from CPSC's extension-cord alert, and it carries no spec_key because writing data/specs.json is refused to a drafting agent. Sources are staged in data/sources-additions-check-a-surge-protector-and-know-when-it-is-spent.json for the same reason. recalls is empty and the CPSC category listing was read on the draft date to prove it.

Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.

Comments and corrections

Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.

Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.

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