How does a Surge Protector Work?

A Surge Protector restricts damaging high voltages from entering electrical devices. It also protects against daily unnoticed smaller surges known as ‘electronic rust’, which does not immediately damage your equipment but shortens its lifespan over time as if it were rusting.

So, let’s break down those heavy words and get into the meat of it.

What is a power (voltage) surge or spike?

Power surges and spikes happen all the time, as many as a few thousand times a day. 

According to the NEMA Surge Protection Institute.

A voltage surge is a mild rise in voltage; it takes some time (in microseconds) to reach its peak and usually lasts between 10 to 1000 microseconds. In comparison, a voltage spike is a sudden and immediate extreme rise in voltage that lasts less than 3 nanoseconds and could be in thousands of volts.

For reference, a Second has 1,000 Milliseconds.

Millisecond has 1,000 Microseconds.

And a Microsecond has 1,000 Nanoseconds. 

A mild rise in voltage is up to 35% above the wall outlet voltage. In North America, where nominal voltage is 120v, that would be an increase of up to 162v hence being mild.

The long duration of the peak (up to several seconds in some rare cases) allows heat to set in, which will fry your sensitive electronics. At this point, your surge protector is really taking a hit to protect your connected devices and appliances. 

It is also worth noting that there is no standardized definition for a surge or a spike. For example, reputable companies like Sweetwater have their own definitions. We at ET present to you the National Electrical Manufacturers Association’s definitions as it is the publisher of standards for electrical products, household electrical outlets, and plugs in the US.

Why do electronics need surge protection?

Surges happen all the time from either external or internal sources. You would be surprised to learn that 70% of surges are started internally from your house. A washing machine motor that goes on and off, a vacuum cleaner, or your air conditioner’s compressor are all sources of internal surges and line disturbances that affect sensitive electronics such as TV, laptops, and sound systems.

Electrical and electronic equipment are usually rated to run on a specified voltage. However, a power surge could exceed the safe threshold and causes your equipment to overheat as it absorbs far more energy than it was meant to handle.

Surge Protectors work at rerouting that extra energy away from your valuable equipment.

Surge Protectors use many different technologies like GTD (Gas Discharge Tubes), TVS Diode (Transient Voltage Suppressor Diodes), SAD (Silicon Avalanche Diodes), and many more to redirect that extra energy and save the day for your dear electronics.

Now, the star of all these components is called an MOV (Metal Oxide Varistor).

What is an MOV?  

An MOV is the most commonly used component in surge protectors as it reacts in nanoseconds while surges take a few microseconds. An MOV becomes a conductor in the event of a power surge and redirects the surge’s energy away from your electrical equipment to keep them safe. 

A typical voltage surge will take a few microseconds (1 microsecond is 1,000 nanoseconds) to reach its peak, allowing more than enough time for the MOV to kick in and redirect the energy away from your devices.  

How long do surge protectors last?

A surge protector has a limited life by design. Every time an MOV absorbs a surge, it degrades and becomes weaker. It is, therefore, essential to buy a surge protector with an indicator light to make sure that it is still functioning and able to protect your equipment.  

A surge protector’s lifespan depends on how many surges it is daily subjected to before the MOV sustains irreparable damage. As the MOV absorbs energy to become a conductor that reroutes the surge away from connected devices, it degrades and becomes weaker.

On a side note,

MOVs need to absorb high voltage in order to work and therefore, do not protect your devices from low voltages (voltage sags). Voltage sag protectors are entirely different devices designed for their specific purpose.  

Do surge protectors work?

Surge protectors do work as long as they are UL 1449 certified, have a decent clamping voltage (400v or less), an automatic shut-off (only for sensitive electronics), a high joules rating (2000 and above), and a response time of less than one nanosecond. 

You will find more explanations of these criteria in the sections below on how to choose a surge protector.

Do surge protectors work against lightning?

There is a common misconception that surge protectors are lightning protection. 

Surge protectors DO NOT protect from direct lightning strikes to your house or building, but they protect against Voltage Surges in your wall power outlets. Lightning rods protect your house from lightning. 

A surge protector is not lightning protection, short-circuit protection, over-current protection, or even ground-fault protection. A surge protector protects against voltage surges caused by many factors. Lightning that strikes the power lines near or far from your house is one of many reasons a voltage surge may happen. 

How to choose a surge protector?

When choosing a surge protector, you will need to look for a few vital pieces of information. 

Remember that the primary purpose of a surge protector is to protect your electronic equipment. So in order of priority, you need to buy a surge protector that will NOT conduct electricity to your equipment if its surge protection is not working anymore (unless it’s a Fridge! no one likes rotten food).

 1. UL Certification: Has the surge protector passed functional testing? 

UL 1449 (3rd edition safety standards) certified surge protector ensures 

  • Quality hardware & build, 
  • Compliant technical design,
  • Compliant Specifications

In plain words: it has passed the laboratory test against voltage surges.

Having a certified surge protector ensures it is built to do what it is supposed to do.

Many surge protectors are NOT UL certified. You should steer clear from any of them as they are just power strips with no protection whatsoever. Regardless of what is written on the packaging. Make sure the UL reflective hologram sticker is on your surge protector:

2. Clamping voltage: When will the surge protector kick in?

Clamping voltage is an essential criterion for a surge protector. Unfortunately, many brands will not clearly state their product’s clamping or clipping voltage in their technical guide due to their poor performance.

The clamping voltage, also known as the “let-through voltage,” is the tipping point at which your surge protector will start working. 

As per the UL 1449 rating (mandatory compliance in the US), the let-through voltage for a surge protector should be 400 volts or less to effectively protect your devices.

It is known as the “let-through voltage” because your surge protector will only ‘let-through’ anything below 400 volts and start routing any extra voltage away from your devices if your wall outlet happens to give out more than 400 volts.

So, 400 volts or less is a good Clamping Voltage which indicates that your surge protector understands when it should start protecting your equipment.

3. Automatic shutoff: Will the surge protector disconnect if it stops protecting my equipment?

Many surge protectors will still act as power strips after they lose their ability to protect against surges. 

A surge protector with an automatic shutoff will stop connecting electricity to your devices and appliances if the MOV protection fails from either a voltage spike or degradation over time.

Suppose the surge protector takes a harsh blow or cannot protect your equipment anymore. In that case, it will automatically shut off and, more importantly, stop conducting electricity to your connected equipment and devices. 

4. Joules Rating: How much energy can a surge protector absorb before it fails?

A surge protector joules rating is the energy absorption/dissipation rating. It tells you how much energy the surge protector can absorb before it fails. 

A surge protector needs to be at least 2,000 joules or higher to protect itself from degrading too fast or frying itself too soon. That is much like making sure that a bodyguard is robust enough to take a few punches. You don’t want to be buying a new surge protector every few months, hence the high joules rating.

5. Response time: How fast will the surge protector respond when the surge occurs?

Not only it is good to know that your surge protector understands when to kick in (clamping voltage), but it’s also good to know that it can jump in and start working as soon as possible (response time) before surges or spikes reach your equipment. 

It is typically expected for surge protectors to have a response time of less than one nanosecond.

6. Power Rating: How many devices can I connect to a surge protector?

What do you plan to hook up to your surge protector? Not all surge protectors have the same power rating and most can only stand a few electronic gadgets.

Make sure your surge protector strip is at least rated for 15 amps which is enough for electronic devices (gadgets like phones, laptops, monitors, etc..). Home appliances and heavy equipment should have their own dedicated surge protectors which only have a single outlet.

7. Indicator Lights: Is the surge protector still able to protect my equipment?

So what does the green light mean on a surge protector? It means that your equipment and electronic devices connected to the surge protector are currently protected from power surges. You should unplug all devices if the light is ever off.

8. Phone line Protection

Surges also come through phone lines. A surge protector with phone line protection is great to plug in your handy and loyal home phone.

9. Coaxial Protection 

The coaxial protection is actually a lifesaver but will slightly slow down your connection (max 100mbs/s)!

10. Ethernet Protection

As surges come through phone lines, they can severely damage your internet router.

11. Circuit Breaker

Surge protectors damage themselves to save our equipment. Overloading a surge protector can damage it and even cause a fire. It is always a good idea to make sure that your surge protector has a circuit breaker.

Below is an excerpt from the owner’s manual of the best surge protector strip I ever bought! 

“DO NOT OVERLOAD the surge suppressor’s outlets. The surge suppressor can accommodate a total equipment load of up to 15 amps (whether plugged into a single outlet or spread out over multiple outlets). If the load on the surge suppressor exceeds 15 amps, the circuit breaker will trip and the outlets will stop providing power. If the circuit breaker trips, reduce the load by unplugging some devices. Depress the circuit breaker to reset.” Link to the full manual here.

12. Replacement Warranty: will the surge protector be replaced if it stops working?

How do you fix a surge protector? You don’t; it is replaced for free by the manufacturer.

13. Equipment Insurance: does the surge protector manufacturer ensure my connected devices?

Most surge protectors manufacturers will have some form of insurance. Yet they are usually contrived with many confusing details. Choosing a reputable brand will save you headaches as you will not only be purchasing a good protector but also honest insurance.

15. Price: How Much Should I Pay For a Surge Protector?

A cheap surge protector is a clear indication that the manufacturer could not have possibly included the right components to offer you the proper protection. In addition, quality products cost more money to be produced as they require more time, design, effort, and expensive raw materials. 

Forty bucks are nothing to protect a thousand or even a couple of thousand dollars tv, sound system, laptops, or any sensitive electronics plugged in your home’s outlets.

What is the safest surge protector?

The safest surge protector is a device that has low clamping voltage (400 volts or less), high joules rating (over 2,000 joules), and a low response time (less than 1 nanosecond). Other safety features such as a light indicator, a circuit breaker, coaxial and phone line protection are recommended. 

Which Household items need surge protection?

All appliances household appliances containing sensitive electronic components (think fancy fridge) need surge protection.

All electronic devices such as TVs, laptops, printers, and sound systems need protection.

A final note for Fridge Protection

Make sure that your fridge surge protector has only one single outlet for the fridge. If your surge protector has a built-in circuit breaker, other connected appliances or electric devices may trip it, leaving your fridge with no electricity and leaving you with rotten food AND possibly an unrecoverable fridge. 

You should also consider buying a surge protector without a built-in shut-off to avoid spoiled food if protection fails, of course, assuming that you keep an eye out and replace that surge protector before the next unexpected surge.

Most portable wall-mount surge-protectors will be 15A devices. Connecting a fridge and a microwave on the same surge protector will already be borderline acceptable. It is better to have your fridge and microwave on different outlets if you can (or even different circuits in case your circuit breaker trips).

What is Energy Trove’s recommendation for a Surge Protector?

Best Single outlet surge protector (Link to Amazon)

Best Power Strip Surge Protector (Link to Amazon)

Does a surge protector protect against low voltage? 

Most surge protectors and even some of the best ones do not protect against low voltages, also known as voltage sags or brownouts. Therefore, you will have to look for a Low Voltage Surge Protector/Suppressor.

Do home insurance companies cover power surges?

According to Worth Ave Group:

Home insurance companies do cover power surges. However, some companies will play with the terms surge and spike for the sake of confusion. Whether or not a power surge is covered by home insurance is based on the policy’s definition of what constitutes a power surge or spike.

Be very careful when buying home insurance and do your due diligence. 

Final thoughts

Remember that 70% of surges and disturbances are internal and start inside of your home. For example, your washing machine, air conditioning, and any heavy equipment with a motor or compressor will cause a power surge on your home electrical circuit. 

Home wiring done adequately by a qualified electrician is essential to avoid ruining your sensitive electronic equipment and decreasing your surge protectors’ lifespan. 

Suppose your TV flickers when your AC goes on, or your PC resets when you put a load in your washing machine, or even your washing machine stops during a cycle. In that case, this is all due to internal line disturbances, and you should contact your electrician to separate heavy equipment from typical household small appliances properly.  

Surge Protectors have a limited life as they degrade every day from unnoticed transient surges.