Surge protectors are a simple way to protect electronics from electrical damage. Power surges can range anywhere from small impulses that gradually wear equipment down to lightning strikes that could fry everything electrical in an entire building. Not all surge protectors are equal and it is important to know the different features offered before selecting one.


Surge Protectors vs. Power Strips


The terms “surge protector” and “power strip” are often used interchangeably, but they are not the same thing. A power strip is anything that plugs into a single wall outlet and gives it multiple outlets. Not every single power strip out there has surge protection built into it. If a power strip is priced especially low, it most likely does not have any form of surge protection. While these can be used for additional outlets, they will do nothing to protect your electronics from electrical surges.

Surge protectors (also called surge suppressors) are designed to stop excess electricity from damaging anything plugged into them. This layer of protection is measured in joules. Electricity can also have signal issues due to electromagnetic interference (EMI) and radio frequency interference (RFI). There are AC surge protectors along with DC surge protectors. For this discussion, we'll talk about AC surge protectors.




What Are Joules? - Joule Ratings


Different surge protectors have different joules ratings, with more joules found on more expensive surge protectors. The joules rating is the amount of excess electricity that a surge protector can block for the entire life of the unit.

Say you have a surge protector rated for 500 joules. That means it could withstand a single 500 joule hit, five 100 joule hits, ten 50 joule hits, etc. If that surge protector, brand-new, took a 200 joule hit, that would mean it can only block another 300 joules worth of damage. Once all the joules are used up, the surge protector is effectively the same as an unprotected power strip.

Unfortunately, there really is no way to tell how many joules a surge protector has left. Most surge protectors make no indication when they stop working. Sometimes it is easy to predict when a surge protector will kick in, like if an electrical overload makes a transformer nearby explode. But little hits during smaller issues with the electrical grid are undetectable and will add up over time. It is a good rule of thumb to replace surge protectors every so often.



How Many Joules Do I Need?


Needing a surge protector and not having it is a lot worse than having one but never needing it. And nothing hits that home like having to replace your TV, computer, refrigerator, and every other electronic in the house during an emergency. For good protection, small devices such as alarm clocks and countertop kitchen appliances should use surge protectors rated from 400 to 999 joules. For appliances like a fridge or bigger electronics like a TV, 1000 to 2000 joules is the best option. For expensive items, like a home theater system, something over 2000 joules is works best.

These are ideal numbers to aim for; having some joules is ultimately better than having none when working on a budget. Options may also be limited depending on what additional features are needed (how many outlets the unit has, are USB ports included, etc.). These high ratings are also what should protect equipment in a worst-case scenario. If the area has frequent thunderstorms or hurricanes, electrical surges are more common and powerful surge protectors are recommended. Industrial areas can experience frequent surges from power tool and heavy equipment usage. Even residential areas can experience small surges when equipment like air conditioners or ovens kick on or off.



Surge Protector Voltage Ratings


Like power cables, surge protectors are rated for a certain amount of voltage. If a cable with a  voltage limit exceeding what the surge protector can handle is used, it will likely damage or even destroy the surge protector. To protect equipment from electrical damage and yourself from electrical fires, always make sure that the surge protector being used can handle the amount of voltage that will go through it.

Common, off-the-shelf surge protectors are generally good to go with common household items like televisions and computers. For something more heavy-duty like power tools, checking the voltage rating is always a good idea. The average surge protector will be rated somewhere between 100 and 330 volts.



Electromagnetic Interference (EMI) & Radio Frequency Interference (RFI)


Devices that use electricity, from small cell phones to big appliances like washing machines, generate electromagnetic interference (EMI). EMI interferes with how well electricity goes through power cables, creating “dirty electricity”. When electricity is dirty, it works your devices harder and shortens their lifespan. On top of that, radio frequency signals put out by cell towers and radio towers create radio frequency interference (RFI) that also makes dirty electricity.

Thankfully, surge protectors have built-in protection that blocks EMI and RFI to keep electricity clean. These EMI/RFI filters are usually found in surge protectors rated for higher joules. Surge protectors rated for 800 joules or higher are typically equipped with EMI/RFI blocking. It should say on the packaging (or description, when shopping online) whether or not a surge protector includes this feature. Some less expensive surge protectors do also include this feature, but it is less common.



Coax Surge Protectors


When thinking surge protectors, power cables are generally the first thing that pops into someone’s mind. However, in the event of a power surge, any cable that transmits electricity can be a risk. Coax cables connected to televisions are commonly overlooked and can easily destroy an unprotected TV during a lightning strike or other disaster. Phone lines can also cause electrical damage on landlines, but wall outlet surge protectors equipped with phone jacks can be found at most stores.

Grounding blocks are commonly used to prevent coax cables from causing electrical damage. Coax cables are screwed in and the main block is connected to something that will send the electricity into the ground, like a grounding rod. Grounding blocks work on the same principle as lightning rods that protect tall buildings from lightning strikes. Different grounding blocks will be rated for different MegaHertz (MHz), so make sure to select the correct kind depending on whether the coax cable is for antenna or satellite TV.

Keep in mind that televisions are not the only device around that uses coax cable. Other devices such as security cameras and CB radios also use coax and can be damaged during power surges. Not all devices use the same type of coax connector as televisions and those will require different lightning protectors. Security cameras, for example, typically use BNC connectors and would need this lightning protector instead of a grounding block.