What is a surge protector ǀ Do You Need One?
Surge protectors are used to protect electronic equipment, like computers, TVs, and stereos. While most of us are probably familiar with these devices, few really understand them. Protecting your appliances has become essential, since just about all modern electric equipment can be damaged by a power surge. This article will empower you with the information you need to understand the topic of electric power surges and how to prevent damaged devices, so you can have the assurance that your expensive equipment is properly protected.
One of the most common questions would be: what is a surge protector? How does a surge protector work? How do you know if your equipment is really protected from an electric surge or, to use a more technical term, transient voltage? I guess the best place to start would be to explain what a surge is.
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What is a surge?
All electric appliances are designed to operate at a particular voltage. In the United States, most of the equipment we use in our homes require a nominal 120V electric supply. There is a tolerance of about 10% that allows for minor changes in voltage. Hence, US appliances are typically rated for 110V – 125V. When the voltage exceeds this tolerance, it is known as a surge.
A power surge can cause permanent damage to electric equipment that is sensitive to high voltage (more than it was designed for). While the increased voltage may not always cause a computer, or similar device to stop working, it will inevitably cause some damage. It will shorten the lifespan of just about any appliance, even if the damage goes by unnoticed.
To truly understand what a surge is, and the effect it has on our electrical equipment, we need to gain a better understanding of what voltage is. In all my articles explaining how electricity works, I use the comparison between electric current and the water supply to our homes. It’s easier to understand water, since we can see it, opposed to electricity which is an invisible (often mysterious) force.
Electricity is basically the movement of electrons from a point of high energy to a point of neutral energy. This is known as potential difference. Voltage measures the difference in energy at the point of supply (a generator) and the point of use – our electrical appliances and lights.
Like electrons flowing through a conductor, water flowing through a pipe has potential energy. Essentially, you can use the water pressure from a faucet to turn a wheel which can be connected to a small generator that will convert the potential energy of water pressure into electricity.
Voltage can be compared to water pressure. The potential difference of electricity, between the point of supply and the point of use, is basically the same as the difference between the water pressure in a pipe and the atmospheric pressure at the other end of the faucet.
When the water pressure inside a pipe is too high, the pipe will burst. Similarly, when the voltage in a conductor is too high, it will “burst”. Extremely high voltage can melt the metal conductor or semiconductor.
When the voltage is high enough to damage appliances, it is referred to as a surge. High voltage for a shorter period is called a spike. To be classified as a power surge, the voltage increase lasts at least 3 nanoseconds. A spike lasts for 1 – 2 nanoseconds.
What causes a surge?
An electric surge is usually caused by changes in electric demand, usually during high peak times. It may also be caused by faulty equipment supplying the utility power. Voltage increases along the supply grid are common.
The surge could be minor or excessive, depending on a number of factors. A less common cause of surges is lightning. While lightning seldom causes a surge in the grid electricity supply, it is the most dangerous, sending millions of volts through a conductor supplying electrical power. Because the surge created by lighting is so great, there is no method of protecting equipment from a lightning surge. The only thing we can do to prevent lightning damage is to disconnect our appliances by unplugging them.
Surges resulting from problems in the grid are fairly common but not always dangerous. It will depend on the how high the increase is in voltage, and for how long this increase lasts.
Electrons move incredibly fast, about 90% the speed of light. Alternating current oscillates between hot and neutral at a frequency which, like voltage, should be within 10% of the rated frequency. In the US, standard AC frequency is 60 Hz. This means that the AC sine wave oscillates 60 times per second. Because electricity moves so fast, there is very little time for it to adjust to changes in demand.
If you’ve ever used a portable generator, you would have noticed how the engine tends to labor for short periods as we switch equipment on. This is because the engine cannot increase speed as fast as the electricity is able to move from the alternator to the point of use.
The electricity grid utilizes several large power generation plants, all producing megawatts of power. This electricity is transported over great distances. In order to conduct electricity over hundreds of miles, the voltage needs to be much higher than the power we use in our homes, which travels over a relatively short distance. High voltage is essential for the efficient distribution of electricity over long distances.
There are various points of distribution between the power generation plant and our homes. At each step in the supply of electricity from the grid to the point of use, the voltage is decreased, depending on how far it is from the end user. The final step in the chain would be the transformer that supplies electricity directly to the consumer. These supply the 120V/240V electricity to our electric panel which is distributed through the home.
Monitoring and managing the voltage at every stage of the electricity supply process is complicated and not always reliable. Just like the portable generator that experiences difficulties when the demand increases rapidly, the power grid may not always remain stable. This just happens on a much larger scale when we’re dealing with an electricity grid that is supplying megawatts of electricity to millions of homes, businesses, and factories.
Because of its vast size, the electricity grid is able to absorb a lot of the changes in power demand. However, the closer we get to the point of supply, the less this is possible. A transformer that is supplying 10 or 20 homes has a limited capacity to supply a constant voltage. Even the mass electricity supply for an entire city can experience difficulties when large air conditioners and factory equipment switch on and off.
Changes in load within the home, as we switch high-current equipment on and off can also cause a power surge.
Inductive motors, used in everything from washing machines and refrigerators to industrial equipment, require a high current to start, up to 3-times (sometimes more) than they use when running. The inrush current required to start an inductive motor is very brief. For this short time, the transformer supplying electricity to that motor needs to increase the amps rapidly. Once the motor is spinning, the capacitor no longer requires the extra current and the transformer has to reduce the supply amperage just as quickly.
A city electric supply has to contend with thousands of high-current startups constantly. Most of the time, the transformers and capacitors used to supply this electricity are able to adapt to these changes without too much of a problem. There will be times when the demand for electricity increases rapidly and then decreases just as rapidly on a very large scale. This often happens during a heat wave, when every air conditioner in the city is cycling on and off in rapid succession, there is a huge change between peak and normal amperage demand.
Even in normal conditions, domestic transformers (supplying our homes) can be pushed to the limit during peak demand times. In the early evening most people are preparing food, using hot water, and heating the home. This increase in electricity demand can be a strain on the local transformers supplying these homes. Power surges are most likely to occur during these peak demand periods.
Engineers calculate the average and peak power demand for every stage of the electricity grid, with a good tolerance for abnormal increases. For the most part, this works well. In a perfect world, we should always have a good, stable electric grid, without power surges. Though, with billions of electrons darting back and forth 60-times per second with unpredictable regularity, there is a chance that things could become chaotic.
I suppose this may be the best way to explain what causes a surge, chaotic (or abnormal) operating conditions. To keep the voltage stable throughout the electric grid requires a sophisticated system of industrial capacitors, transformers, and computer systems to stabilize the supply. As this equipment gets older, it may not be as effective, especially when the load demand is pushed to the limit. Aging transformers and control equipment will be less capable of maintaining a perfectly stable electrical supply. As a result, the voltage can increase to dangerous levels, causing a surge, especially when electricity demand is high and power usage is erratic because of rapid changes caused by inductive (non-linear) load.
Power surges in large cities are unavoidable. In some areas it may be worse, if the supply infrastructure is old or not correctly maintained. Since we never know when a surge will occur, or with what regularity, we need to protect our appliances using a surge protection device.
What is a surge protector?
A surge protector (or surge suppressor) is most commonly installed inside a power strip. It is also possible to install a surge protector at the point of supply to your home, in your electric panel. These will protect the entire house from surges caused by the electrical supply. A whole house surge protector will not protect against surges that happen within the house as appliances, like air conditioners, microwaves, and washing machines switch on and off.
Because it offers full surge protection at the appliance, most of us will probably be using the more common type of surge protector. This is an extension cord that is plugged into an outlet and supplies a strip with several outlets.
Since I started out by explaining voltage as being similar to water pressure, we’ll continue with this analogy. The principles remain the same.
Just like a pressure valve that keeps water pressure from causing a burst pipe, a surge protector will prevent high voltage from damaging electrical wiring and semiconductors
A water pressure safety valve basically dumps the excess water back into the main supply, only allowing the requisite amount of water to flow through to the point of use. Essentially, most surge protectors perform a similar function. They dump excess voltage to the ground wire, only allowing the correct voltage to flow along the hot wore to the appliance.
How does a surge protector work?
The most common type of surge protector is a strip with several outlets, which is plugged into the wall outlet. When the power surges or spikes, the excess voltage is directed to the ground wire, which is connected through the electrical supply to both the neutral supply and the ground – via a ground spike. The ground acts as a virtual sponge, absorbing the excess voltage. Various methods can be used redirect excess voltage to the ground wire.
Most surge protectors utilize as a Metal Oxide Varistor (MOV), using semiconductors that react to high voltage. A semiconductor will either conduct or resist current depending on the input voltage. The MOV is connected in parallel between the hot wire and the ground wire. When the voltage is normal, the semiconductors controlling the flow of electrons resist the current, preventing them from being conducted to the ground wire. If the voltage increases, the resistance is lowered, causing some of the current to flow to the ground wire, only allowing the required voltage to be conducted along the hot wire to the outlets.
This variable resistance acts like a gate or control valve, redirecting electrons. Only those electrons that are required to supply power to the outlets are allowed to flow along the hot wire. The excess electrons, which cause a voltage increase, are directed away to the ground wire.
Another method of achieving the same result is to use a gas discharge arrestor, which is also called a gas tube, using the same basic principle as a fluorescent light. A tube filled with an inert gas, which is ionized at a high voltage, is connected between the hot and ground wires. When the voltage is normal, the gas will not conduct electricity. When the voltage increases, the gas will become a conductor.
A less common type of surge protector utilizes a shunt which is connected in series along the hot wire. When the voltage is normal, electrons flow through the suppressor unrestricted. As the voltage increases, the movement of electrons is slowed. This prevents the excess electric energy to flow to the outlets. As the voltage decreases, these electrons are released. One of the advantages of using a voltage suppressor connected in series is the instant reaction. A MOV or gas tube will either conduct or resist electron flow to the ground wire in reaction to the voltage, this means that the semiconductors or gas tube are constantly changing the flow of electrons during a surge. There is a delay as the conductivity changes, albeit very short. A shunt never changes conductivity, it only restricts the speed of electrons and, therefore, has no delayed reaction.
Apart from controlling high voltage by suppressing or redirecting it, surge protectors can also include a line conditioner. This is a device that filters line noise, which is small variations in the sine wave. The most basic, and very reliable method of filtering line noise is to use a toroidal choke. This consists of a magnetic ring with wires coiled around it. The hot wire will pass through the center of the magnet and the electromagnetic field around the hot wire will be equalized by the force of the magnet.
It is always a good idea to use a surge protector with a fuse. This provides additional protection, the fuse will break the circuit if it is overloaded, preventing any electricity from flowing to the outlets.
Do all your appliances need a surge protector?
Some electric appliances are more vulnerable than others when it comes to surges. High-watt resistance equipment, like water heaters can withstand most power surges and really need to be protected.
Your refrigerator compressor can, in certain circumstances, be damaged by a surge, though not always. It is not uncommon for a refrigerator to fail when power is restored following an outage. In the first few seconds after a blackout, the electricity grid is incredibly unstable. With all the equipment in the area staring up at exactly the same time, utility surges are almost inevitable and can be severe. If you don’t have a surge protector for your refrigerator, it is advisable to switch it off during an outage and only switch it on about a minute after the power has been restored. This could be an unwanted hassle, and you won’t always be at home to do this. A surge protector is probably the best solution to prevent damage to appliances like refrigerators and air conditioners.
Electronic equipment has the lowest tolerance against surges. Your computer, TV, stereo, router, and similar devices should have local surge protection. This would be a strip with a surge protector or suppressor, plugged into the outlet that supplies these sensitive devices. Some surge protectors include ports for the phone line, providing additional protection from surges that can occur through the phone or DSL connection.
I’d recommend a high amp / high volt whole house surge protector to protect the main utility supply to the home. This would be installed at your electric panel. A whole house surge protector will protect the more heavy duty equipment, like refrigerators, from a surge in the utility power. Though, just like a utility surge after an outage, you may also experience a local surge when all your appliances startup at the same time. Since a whole house surge protector only protects against surges in the power entering your home, not surges that occur within the home, additional protection will be required for the more sensitive electronic equipment. This would mean that, in addition to the whole house surge protector, local protection will be needed for outlets supplying computers and the like.
This may seem like an expensive undertaking but think of it as insurance. Fortunately, unlike insurance, you don’t have to spend this money every month. A once-off installation of quality surge protectors for the house, and additional protection for equipment that is particularly vulnerable, will ensure that you don’t end up with a huge replacement bill when a surge occurs.
The Best Surge Protectors
The temptation exists to buy the cheapest surge protector. Though, a $5 surge protector is not really the best solution. There’s little point paying for something that is not going to do the job that is intended for. Cheap surge protectors may fail completely and usually need to be replaced after a surge. This means that may not get full protection (your equipment may be damaged) and you will probably have to replace the cheap surge protector after every power surge. In my opinion, this is just a waste of money, without much reassurance that your expensive electronic appliances are fully protected.
High-end surge protectors can end up costing north of fifty bucks, with some costing well over $100. If you need several strips to protect equipment all around the home, and a whole house surge protector, this can end up costing way more than you would like. Even if you’re prepared to pay top dollar for the best surge protector, how do you know you’re actually getting what you paid for?
Simply choosing the most expensive surge protector is probably not the best way of ensuring that you’re getting what you need. You may be able to spend less and still get the right protection. You need to know what to look for.
The most important specification, in terms of power surge protection, is the rated joules for a surge protector. This specifies how much energy the surge protector can handle. A surge protector strip that is required to supply a lot of power, should have a higher joule spec.
The amount joules that a surge protector can handle will determine how much energy it can divert to protect your equipment, whilst still supplying all the amps needed to keep that equipment running normally. If the joule rating is too low, it will keep supplying power even if the voltage is too high and may easily fail completely. Cheap surge protectors, rated at around 200 to 400 joules aren’t going to offer much protection, especially if you have quite a lot of equipment plugged into the strip. I’d recommend at least 2,000 joules. Though, more joules, even if it is not really necessary, will be better. A surge protector, like the Tripp Lite ISOBAR6 ULTRA [B0000513US/] (rated for 3,330 joules) will withstand greater surges, supply more watts reliably, and last longer than others with a lower joule rating.
To ensure that you’re actually getting a quality product, look for the UL 1449 safety standard. The UL standard means that the product has been independently tested by an underwritten laboratory (UL).All electrical equipment should meet the UL safety standard for that type of equipment – UL 1449 is the applicable standard for surge protection equipment. I also recommend a fuse or circuit breaker protection as a final line of defense against equipment damage.
Once these basic requirements have been met, you will want to look at practical considerations. Having more outlets than you need is always an advantage. You never know when you may need to plug in more equipment. The spacing of the outlets can also be an important consideration. A bulky charger or power supply, plugged into a strip with outlets that are close together, can easily render several outlets unusable. USB ports and CAT5 connectors, for networking, phone, and DSL lines will provide another layer of protection for your router, modem, or other networking devices.
The Ultimate Solution
Having spent many years in the power supply business, I was faced with the challenge of providing 100% safe electricity for really sensitive equipment, like laboratories, hospitals, and the aviation industry. Not to mention industrial plants that experience massive power surges on a regular basis. As a result, I have a lot of knowledge on the topic of reliable voltage, frequency, and surge protection on a scale that extends way beyond our normal domestic needs.
The very best power protection, for a true sine wave, and 100% surge protection is an online (double conversion) uninterruptible power supply, or UPS. This is the type of equipment I would supply to a hospital or laboratory that needs uninterrupted power, that will won’t shut off when the utility fails, and the cleanest power, usually with less than 1% Total Harmonic Distortion (THD). Though these UPS systems are really expensive and not required for the type of electricity we use in our homes.
I believe the system I installed in my home (after many years of industry experience) is the best and reasonably inexpensive for what it provides. Okay, reasonably inexpensive in this context means around $1,000. A very different league to the average surge protector. Though, I should explain what this system provides, it doesn’t have to be as expensive, depending on what you need.
You’ve probably seen a small desktop UPS. You may even use one for your computer. A standard desktop UPS offers a good deal of surge protection and has a built in battery that will continue to provide power for a short period when the utility power goes down. The problem is that they don’t allow you to keep using power for longer periods and can be damaged by a surge. This means that your computer is probably going to survive a surge, but the UPS may have to be replaced. You typically have enough time to shut your computer down and no more.
If, like me, you live in an area that has regular outages that can last for a long time, a line interactive UPS with a large battery storage capacity is the best solution for protecting your equipment and providing backup power for longer periods. It’s possible to provide enough battery backup for several days with the right UPS.
I installed a top quality 1000 VA line interactive UPS, with a CPU management system, and 2 X 100 AH deep cycle batteries. The UPS is similar to the CyberPower PR1000LCD [B0083TXNPE]. A UPS like this has a sophisticated management system. If it detects any type of abnormality in the utility power supply, it will instantly switch to battery power and keep supplying uninterrupted power using a pure sine wave inverter. Both the UPS, and all equipment plugged into it, is 100% protected from any type of surge or high THD from the utility supply. The UPS will completely disconnect the utility power, if it detects that this may cause damage to the unit, without interrupting the supply to the UPS outlets.
You may not need as much battery backup as I decided to use. Since I experience outages that can last an entire day, I opted for more (rather than less) battery storage capacity. I installed the UPS in my home office. Since I work from home, this investment was worth it. From my office, I installed wiring to my electric panel and connected all the lights in my home. I also installed a dedicated UPS outlet in the living room for my TV, stereo, and satellite receiver. All this power is supplied from the 1000VA UPS in my office. This supplies roughly 800W continuously with a peak capacity of about 1,200W. That’s enough for all the equipment to run simultaneously. I only use LED lighting which means that my electricity consumption for lights is very low. The UPS would not be able to supply high-watt lights, like halogen security lights.
With this system, I not only have complete protection from surges and any other type of abnormality in the utility power supply, I can also keep working when the power fails. It also means my lights, and entertainment system don’t switch off when the power goes down. Even though the expense is much higher than simply installing a few surge protectors, the numerous benefits work for me. The UPS system has been running perfectly for almost 10-years, having replaced the first set of batteries after about 7-years. Well worth the investment for all these years of convenient, uninterrupted power supply, and zero damage to any of my appliances. Unlike a generator, UPS power never goes down, it switches to battery automatically without the equipment shutting down. It’s a win-win solution for complete peace of mind, albeit at quite an expense.