Exactly What Does “Joules” Mean?

f you’ve been reading about surge protectors and saw the term “joules” in the specification section and weren’t exactly sure what that means, you are not alone. I did a little research and wrote this post to give a SIMPLE yet understandable answer for you. Enjoy!

The best and most simplified definition I could find comes from Merriam-Webster. But in my opinion, it’s still a bit technical. So here’s both 🙂

(More Technical)

Definition of Joule:

A unit of work or energy equal to the work done by a force of one newton [Newton- the SI (Standard International) unit of force] acting through a distance of 1 meter.

A joule is energy (dissipated as heat) when one ampere of electric energy passes through a material with a 1-ohm resistance for just one second. The Joule is named after James Prescott Joule, who was an English physicist.


Definition of Joule:

(Regarding- Surge Protection)

Basically, the joule rating is an indication of the amount of energy that can be absorbed by the surge protector before it fails.

The protection provided is higher when the number of joules rating is high. The value and type of the equipment needing protection serve as bases to determining the joule rating needed.

Why Do Joule Ratings Matter in Surge Equipment?

When selecting a surge protector, the most significant factor to consider is the joule rating of the surge protector. Other factors to consider include the number of outlets, the best length of cord and preferences like a coaxial cable connection protection.

With surge protection equipment, joules are the “amount” of protection offered. Think of it as a protection reservoir. For instance, for a product that has a protection of 1,000 joules, it means that it can take 1-1,000 joule hit (or 10-100 joule hits). In general, the higher the joules number, the better.

What Types Of Surge Protectors Exist?

  • is-it-real-surge-protectorPower Strips: this is the cheapest surge protection available which has some ten-cent protection parts, costing about $4. With glorified brand names it may go for $25 or even $150. But if you look carefully at the specifications sheets, they carry very little protection. Remember to read the specs.
    Ask yourself, “How will the product’s 100s of joules absorb damaging surges that are hundreds of 1000s of joules?” Simply put, it won’t. Unless it’s something cheap like a small electronic device or appliance that won’t break your bank if you need to replace, steer clear of using this product completely by itself.
  • electric-saver-1200-surge-protectionWhole House Surge Protection: This type is utilized in many facilities that require superior protection of their equipment against destruction. Typically, lightning requires 20,000 amps.

    A minimally sized “whole house surge protector” should start at 50,000 amps. After each and every direct lightning strike, just about every form of surge protection will gradually deteriorate to the degree that it has been hit with mild or heavy surges. (eventually leaving you unprotected again)

  • uninterruptible-power-supplyUninterruptible Power Supply (with Surge Protection): This type of surge protection is perfect for computers/gaming or other equipment where you need to save your work (or game) 😉 before shutting your equipment down in a storm. Having a UPS isn’t required for EVERY appliance or small electronic in your home, only those systems requiring a few more minutes to properly save work/games before shutdown of all power. This type of protection also helps with brownouts occurring.
    To Read more about brownouts and how they also damage your home- Click Here.

Surge protection is about the energy or surge being diverted before it causes damage to electrical items on your property. Whether the electrical surge comes from inside your home or business or from the outside, the surge protector will attempt to divert it safely and quickly to ground outside.

Since you need to protect all your important electronics & appliances, this list could be long or short depending on what is in your home or on your property.

Most Common Things That Need Surge Protection:

  • refrigerator-washer-dryerAir Conditioner or Heat Pump System (as well as furnace if you live up north )
  • Dishwasher
  • Refrigerator
  • Clothes Washer (many newer model have Electronic Boards in them)
  • Clothes Dryer (same as above on Electronics)
  • Ceiling fans
  • Digital clocks
  • TV, DVD, &/or Home Theater System
  • Other Small Appliances and Electronics

    * Note: With some of the above items, it isn’t realistic to have an individual surge protector installed/wired into it. Having a surge protection system that covers your entire home or business is the best solution.

How Does a Surge Protector Actually Work?

direct-lightning-strikeWhen the voltage upsurges above the normal level, the surge protector prevents the excess voltage from causing damage to your property by diverting it.

Precisely, components known as metal oxide varistors, inside the protector, absorb this excess voltage and then safely divert it to the ground via the neutral/ground wire.

But, the downside is MOV’s are usually only good for 1 surge and then, POOF-That’s it! Now, you have to replace all your surge protection devices. But what if you didn’t have to? If there were a surge protector that came with a lifetime warranty, and used a much better technology than MOVs, would you buy it if it were affordable? Click Here to read more about this top of the line lifetime surge protector.

Do you have a lot of computers or electronic equipment that needs protection? How do you determine if additional individual surge protection should be installed on that equipment? Short answer is… it depends on the equipment. frustrated without surge protection

frustrated-power-billsAnything you don’t have the budget to replace at a moment’s notice (or you are smart and want to avoid the hassle) should be protected. And if you own a business, protecting your computers/equipment and preparing for things like this are important. By doing so, you can easily save thousands of dollars against just 1 occurrence.

How Many Joules of Surge Protection Do I Need?

Are you seeking to protect a $5,000 home theater or a $500 personal computer? Clearly, as the value of the equipment you want to protect increases, the quality of the surge protection should also be higher. We always recommend getting a whole home surge system, as well as protecting your most expensive electronics/equipment on a dedicated system.

Surge Protector Joules Chart…

Generally, the joule rating is a very important factor when it comes to surge protectors. Considering the type of equipment you are protecting, as the value of the equipment increases, the quality of the required surge protector should also be higher. The table below shows a summary of the recommended surge protector joule ratings for various devices.



Up to 1000 joulesLow-priced devices like digital clocks, blenders, lamps etc.
1000 up to 2000 joulesFor office equipment (like routers, copiers, printers) and power tools etc.
2000 joules and aboveFor televisions, gaming consoles, home theater components, computers storing important data etc.

Location Consideration…

lightning-strikeDo you live in a region where lightning storms occur frequently? If so, a higher protection level is required including a higher joule rating. However, not all surges threatening your electronics are created by Mother Nature.

Your utility company’s power grid can experience problems that can also cause huge power spikes on your property. In industrial areas, heavy equipment and tools can cause line interference and damaging surges too.

However, in most residential areas, up to 80% of all small surges come from inside the home. Instances within your home that can cause small surges include:

  • Oven or refrigerator turning on and off.

  • When the air conditioner cycles on…
    (hint hint…. When the lights sometimes dim from it turning on, that’s the same thing as a brown out which is just as damaging as a surge. The surge happens when it now turns off. Read more about brownouts here.)

  • When a large power tool starts up like table saw, compressor, etc.

  • And other large motors or equipment on your property cycles on.

If you suspect that your home has small power surges from 1 or more of the situations listed above, contact your local electrician to check out your electrical system. Sometimes, updating 1 circuit is all it takes to handle a situation. And it’s always a good idea to be safe instead of sorry. Having your electrical system checked out by a licensed professional is the best way to keep your property’s system operating safely.

Is That Surge Protector Still Operating?

In most models an LED indicator lets you know that the device is still in operation. Nonetheless, a person may ignore these lights or they may be out of sight like when the protector is positioned under a desk or behind furniture.

electric-saver-1200-plus-whole-house-surge-protectionAny surge protector that uses MOV technology is a ticking time bomb. If you have been using your surge protectors for a couple of years, or if there has been a major electrical complete whole house surge protector and power saverevent, (like lightning that led to a power failure in your home), NOW is the time to acquire new surge protectors.

Having a top of the line surge protector (like the one I recommend here) will pay for itself in the next few years. However, because of its superior lifetime protection, it also gives you greater peace of your mind… And THAT is PRICELESS.