What Joule Rating for the Surge Protector?

A lot of people ask me this question, and I wish more electricians would know the answer. Many factors go into determining how many joules you need for your surge protector, so it is not as simple as saying “put 8 on” or “4 should be enough”. 

If you are running a small business, then 6 probably will be ok, but if you have a high-end computer system, then 12 may be required. 

The best way to find out what rating is suitable for your needs is by taking inventory of all the different electronics in your office and researching online. You can also call an electrician who has experience with these situations to guide you through the process.

This blog post will explore the different joule ratings for surge protectors and what they mean. Surge protectors are essential to keep your electronics safe from power surges or spikes in electricity. You can use a surge protector with any electronic device-even televisions! 

Finding Surge Protector Ratings

On a listed surge protector, you should find a couple of ratings. Look for:

  • Clamping voltage: Testing the voltage of a MOV reveals how much electricity it can handle. A lower clamping voltage means better protection, and three levels are recognized by UL — 330 V, 400 V, or 500V. Generally speaking, if your clamping voltages are more than 400 volts, then you may be in trouble!
  • Energy absorption/dissipation: Surge protectors should have a high enough rating to prevent catastrophic failures. Ideally, they are rated at 600 joules or more for the best protection available – anything less can result in complete power outages and significant damage to your equipment.
  • Response time: Surge protectors don’t kick in immediately, but there is a very slight delay as they respond to the power surge. A longer response time tells you that your computer or other equipment will be exposed to the surge for a more significant amount of time. Look for a protector with less than one nanosecond reaction times, so it kicks on quickly and protects against surges better!

If you’re looking for a quality power protector, be sure to look for one with an indicator light that will tell you if the protection components are still working. 

All MOVs burn out eventually after repeated surges in electricity from storms and other sources of high voltage. Still, your protectors will continue to work as regular surge-protecting outlets without indicating that they aren’t functioning correctly.

When looking for a surge protector, you may want to invest in one that comes with some guarantee. If the unit fails to protect your computer from an electrical power spike or another issue, then this assures that if it doesn’t work, they will replace your PC altogether! 

This is not total insurance–you’ll still lose all data on the hard drive, and additional costs could be incurred, but it shows confidence by the manufacturer.

If you’re interested in learning more about these issues and finding out all the ways surge protection technology can fail, then check some of the sites listed below. 

Surprising to many is that there has been a great deal of debate on web forums debating if this piece of equipment works or not.

Joules Rating in Surge Protectors

A power surge suppressor is an electrical device that protects electronic devices from voltage spikes, typically on AC mains electricity. 

It can be rated by the number of Joules it absorbs before failing – this rating decreases every time there’s a “blow” to your electronics caused by lightning strikes or transients.

If you never owned one before, the chances are good that you have no idea what Joules means? They’re units for energy (Watt-seconds), and to put things into perspective: 400 joules could mean leaving a vacuum cleaner running for 1 second!

Surge Protector Basics 

A surge protector can protect your appliances and electronics from getting fried during a power outage. But if you buy the wrong one, all that money will be wasted!

A common misconception is that when buying a surge protector, it’s safe to go with any old cheap model because they’re designed similarly anyway, so what difference would there be? 

This couldn’t be farther than the truth: without purchasing an expensive unit made for high-level surges or even more costly models of higher joule ratings which work best on devices like microwaves, computers, televisions, etc., nothing at all will happen in case of extreme weather such as lightning strikes.

Clamping Voltage 

Clamping voltage is the amount of power it takes to activate your surge protector. The lower this number, the better protection you’ll receive from small surges in electrical current. 

Suppose a product has a high clamping voltage and little joules (energy). In that case, even if there’s an average size power surge, these devices still might be damaged because they’re not adequately protected by their system or any other external systems that are supposed to protect them, such as circuit breakers. For example—that would trip off before anything could happen, but alas!


The joule rating of your surge protector tells you how much energy dissipation and prevention it has. But what does this mean? 

The input refers to the amount of power absorbed by the device when a spike or voltage change occurs, such as an event where lightning strikes in close proximity. 

Higher rated protection means more resistance against these surges for more extended periods before they are expended. In contrast, lower ratings will fail after smaller events occur due to less capacity to withstand them.

Surge Protector Joules I Need

A surge protector can save you a lot of trouble if it comes in handy during power outages, but how do you know which are the best ones? The number of joules your device needs will vary depending on what type they are. 

If it’s small devices like phones or laptop chargers, then a few hundred is enough to keep them safe from damage. But when that new $1,500 laptop just arrived home and plugged into an outlet for its first time—well, now we’re talking about needing extra protection!

500 to 1,000 Joules

The best-rated surge protectors are those with joule ratings under 1,000. Those who want to use them without much hassle should consider these smaller devices that can be tucked behind furniture or other items all around the house – from a home office to kitchen countertops.

A surge protector with a small joule rating is the cheapest option. If you’re on a tight budget and only have small devices, this device might be suitable for you.

1,000 to 2,000 Joules 

It is essential to take precautions when it comes to electrical equipment. 

A surge protector with this rating will be able to handle small electronics and other office equipment. At the same time, one rated between 1,000 and 2,000 joules is suitable for protecting cell phones or printers from the surges that may come through your building’s power grid. Protecting yourself from a potential disaster starts at home!

2,000 to 3,000 Joules 

Who could forget the night when you were playing your favorite game, and then all of a sudden, everything turned off? 

If you are not protecting yourself from power surges, this is what can happen. 

With over 2,000 joules in protection for expensive devices like gaming consoles or computers that hold sensitive information such as financial documents or customer data- it’s worth getting one today!

Do I Need High-End Surge Protection Devices?

As home products increase in number and value, more people are seeking ways to protect them. 

According to Credence Research’s forecast that the surge protection market will be worth $3 billion by 2022, it is only logical for consumers with expensive appliances like televisions or computers at home to explore options of whole house surge protector systems capable of protecting their entire homes from harmful power surges and potential fires caused by electrical malfunctions. 

Surge Protector Reviews has compiled reviews on various brands available online, so you can make an informed decision about which one best suits your needs!

If you’re like me, who has invested thousands of dollars into high-end electronics and kitchen appliances, then I’m sure that you will want to invest in a surge suppression system with plenty of joules. This way, they can protect all your prized possessions.

About Blake Sutton

Blake has worked as an electrician for over 10 years, receiving his Journeyman Electrician license in 1998. Looking to take his professional electrical career further, in 2008 he received his Bachelor of Science in Electrical Engineering (BSEE) from the University of Texas in Austin. Blake now works full time as an electrical engineer, specializing in power systems.