From the Wirecutter: The best surge protector for your home electronics

This post was done in partnership with The Wirecutter, a buyer's guide to the best technology. Read the full article with more details and background information here.

Surge protectors don't last forever. Like lightbulbs, they need to be replaced every few years when they wear out. Just because your old surge protector passes power to your devices doesn't mean it's still actively protecting them—in fact, you probably need a new one. After assessing more than 30 hours of research, and 32 hours of testing by an electrical engineer, we found that most surge protectors that cost just above $20 will provide adequate protection from surges. Our extensive research and testing showed that more-expensive units didn't provide enough additional benefit to be worth their higher cost. And of the units we tested, our top pick is the 10-outlet Tripp Lite TLP1008TEL, because it stops passing power when it's no longer effective at blocking surges.

Most surge protectors rely on an easily ignored LED indicator to tell you when they've ceased protecting your gear. We picked the TLP1008TEL because when its ability to block surges wears out, it cuts the power off entirely. So long as your devices are energized, you know that surge protection remains in place and have no ambiguity as to when it needs to be replaced.

If this Tripp Lite is unavailable, the Belkin PivotPlug is also a capable surge protector and has an excellent design that offers more outlets at a similar price. But, unlike the Tripp Lite, it still provides power even after the protection ceases being effective, alerting you by the failure of an indicator LED. You might prefer a unit that functions this way if you're plugging in hard drives or other sensitive electronics that you fear might be harmed by a sudden shutdown, but for most people this won't be a concern. With a total of 12 outlets, the Belkin model includes eight tilting outlets along its sides that allow you to fit all manner of power blocks at myriad angles.

For lighter duty, like under night stands or side tables, the Accell Powramid D080B-015K is the way to go. It has two USB ports and six outlets that are usable even with larger plugs, all in a comparatively small package. The USB ports put out a combined 2.1 amps, enough to charge one smartphone or tablet at high speed or two devices at low speed. Due to the Powramid's small size, Accell used a compact circuit that might not last quite as long, but offers a great deal of protection. Even at their lower price, Accell products safely prevent power from passing through when the protection fails—you'll know when it's time to replace it in a few years.

Tripp Lite's SpikeCube is perfect for traveling in areas with spotty grids. It covers just one outlet, but has performance comparable to that of the bigger picks squeezed into a pocketable package. If you want something on the go with more outlets than the SpikeCube and you are less concerned about surge protection, check out our full travel USB surge protector guide.

Who this is for

A surge protector offers peace of mind when you're concerned about sudden power spikes that could fry your expensive electronics. You may live where severe weather regularly causes power fluctuations (though a surge protector won't help you in the event of a direct lightning strike), or be on an electrical utility's system that can't provide good, consistent power. You may also just want figurative insurance—more about actual insurance later—against an unlikely event that requires a small investment to forestall.

Because a surge protector is a "better safe than sorry" device, experts recommend getting one that stops providing power the moment the internal circuitry that protects against surges stops working. For most people, that isn't a problem, because most modern hardware can cope with the sudden loss of power—and better the loss of a power strip than the destruction of hardware that could cost thousands of dollars to replace.

However, if you have equipment that could be damaged by a sudden loss of power or mission-critical gear that can't ever go down or that needs a specific shutdown or power-up sequence (a hard disk drive, for example), you shouldn't be looking at a surge protector at all. Instead, you want a uninterruptible power supply, or UPS. A UPS is basically just a big battery that you place between your outlet and your gear, and most of them have surge protection built in.

If you live in an area with a stable power grid and a mild climate, you can probably skip the surge protector without too much risk. Ultimately, though, the low cost of surge protectors makes them worthwhile for a vast majority of people looking to stave off this one type of catastrophe.

How we picked

Many home office and home theater surge protectors come with ports that promise to protect your cable or phone lines, but we feel comfortable without them on our main pick. Though phone and cable lines certainly can carry surges into your home, many technicians and Internet providers discourage running data lines through surge protectors because, they say, it can introduce noise and degrade performance—a claim we weren't able to prove or disprove. In any case, our testing and tear-downs showed many manufacturers put wimpier protection (if any at all) on these auxiliary ports, so skipping them probably puts your modem or cable box at only slight risk.

Noise filtering is a common "premium" feature on the more-expensive surge protectors, but because most models performed similarly last year, we didn't test it on this year's models. In any case, all power supplies, whether internal or external, have noise filtration built in—in most cases, enough already to prevent any noise coming in on the AC line from interfering with the operation or performance of your electronics. Noise filtration probably isn't something you need to worry about unless you're having some sort of noise problem (usually manifested as static) in your audio or video gear or computer peripherals.

Though many surge protectors are sold with "connected equipment coverage," we didn't consider that in making our selections. We suggest you read the fine print because often you'll have to leap through a bunch of hoops to collect in the event of disaster. If you want financial protection you can count on, don't get it from a tech manufacturer. Just make sure to double-check that your electronics are covered by your homeowners policy or renters policy.

If your home theater costs more than a compact car, series mode protection may be worth investigating, but the technology isn't worth the huge price tag for most people. These surge suppressors are made by companies like Brickwall and Torus Power, and came on the market much more recently than the metal oxide varistor (MOV)-based protectors that we considered. Series mode protection is superior to MOV-based protection on pretty much every point, except for one big one: cost.

It would cost more than 10 times as much to replace our MOV-based pick with a similar number of series mode protected outlets from a reputable manufacturer. Though the series mode protector will theoretically pay for itself after 30 to 50 years (depending on how surge-prone your abode is), the upfront cost is simply too high to bear for most people. Spending $300 on a device to protect $2,000 worth of equipment from a rare disaster scenario is not worth it. We think it makes more sense to spend roughly $20 for a device that stops passing power when it's kaput and then replace it every few years.

Once we had a good idea of what features we could leave out, we surveyed 835 of our readers to learn about their expectations and narrow the criteria. Most of our respondents have six to seven devices plugged in, but wanted between eight and 12 outlets in a full-featured new unit, and were willing to spend up to $50. Features like USB outlets were less important than designs that accommodate bulky power supplies.

For lighter-duty use, our survey respondents generally had just three or four devices in use and the desire for a couple more, so we focused on units with six outlets that sell for less than $30. The smaller, lower-powered chargers used in a bedroom are less likely to have huge power bricks, so outlet spacing is less important than useful perks like USB ports.

We reached out to the manufacturers to verify clamping voltage, response times, and failure behaviors on top models, and after all that our final test list comprised the Belkin Conserve, the Belkin PivotPlug 12-Outlet BP112230-08, the APC P11VNT3 3020J 11-outlet SurgeArrest, the Tripp Lite TLP1008TEL, and the Tripp Lite Isobar HT10DBS for office and home theater use; and the Accell Powramid, the Accell Power Genius, and the Belkin PivotPlug 6-Outlet for bedroom and light-duty use.

How we tested

Lee Johnson, an electrical engineer with more than 10 years of experience, help set up our testing parameters and meticulously dissected our units for comparison, simulating surges and analyzing the results. He relied on a Solar 7054-1 600V transient spike generator and ATTEN ADS1062C digital oscilloscope to inject spikes into each surge protector on each circuit leg. He tested using a series of surges, from 100 volts through 600 volts at 100-volt increments until the surge protector began restricting or "clamping" the voltage. He repeated testing at this clamping voltage five times for each leg on each unit and recorded the whole process. We followed the same procedure on auxiliary ports for cable and phone, though starting at zero volts.

The difference between the ostensibly top normal AC voltage of 170 volts and where clamping begins (at 330 volts or higher) is called the "let-through voltage," and that is our baseline for comparing surge protector performance. If a protector clamps voltage exactly at 330 volts, the let-through amount would be 330 minus 170—that's 160 volts. The real-world let-through voltage we tested has a direct impact on how much damage electronics might incur.

Whenever we refer in this guide to let-through voltage on AC power legs, we're using the voltage above 170 volts for consistency, including in our charts. With auxiliary ports, where clamping should be at zero volts, we subtract nothing. We didn't want to see more than 160 volts in net let-through voltage.

We often rely on UL's certification, and all the devices we picked have passed UL testing. However, UL certifies surge protectors at multiple levels, and some, like the Tripp Lite TLP1008TEL, are certified at a less stringent 400-volt let-through rating. Tripp Lite's own specs for this model, however, list 150 volts of let-through (320 volts total) as its actual clamping voltage level, and we were able to confirm that in testing. Though we'd prefer the UL rating to be in line with the claimed clamping voltage, we're comfortable that our testing confirmed it. The other picks all have a 330-volt UL rating.

In our chart, we show let-through voltage for each of our picks Johnson tested and across each leg. Both the best and the worst let-through performance came from Belkin, with its 12-outlet PivotPlug letting through just 126 volts of the surge and its remote-switch-equipped Conserve (not picked) allowing 190 volts through. Our top pick, the Tripp Lite TLP1008TEL, was in the middle, letting through 142 volts on the L-N leg.

We found the largest differences in protection on the N-G leg, where the Accell unit allowed 204 volts through but the Isobar only let through 104 V. Of nine models we put through our tests, not a single one stood out as consistently the worst or the best on all branches.

Four of our tested units had auxiliary ports, which should let almost no power through above 0 volts, but only the Isobar's telephone and Ethernet ports had real protection: those ports blocked 90 percent of a 600 V spike. When we sent the same spike through the coaxial ports, they were basically unprotected, allowing 570 V through. The APC Surge Arrest, on the other hand, let just 52 V through on the coaxial line, but offered no protection on the telephone lines. Some manufacturers claim only to "filter" these ports, others claim to protect them. But the difference is often not clear, and the protection wasn't consistent in our tests. Thankfully, though surges are possible on auxiliary lines, they're far less common than on electrical lines.

Results of let-through voltage tests (above 0 volts) on auxiliary ports

None of the models tested provided worthwhile protection on all three port types.

In addition to our bench tests, we took into account Johnson's feedback after he tore apart our top performers. The Tripp Lite and last year's pick from APC had identical varistor components in slightly different configurations. And just like the more-expensive Isobar unit, they all use the same diameter wiring (14 AWG) and they all have current limit fuses and filtering capacitors on the incoming AC line.

The differences are mostly in how the components are used. For instance, both the APC and Tripp Lite units have eight varistors, but the APC unit has three on the L-N, two on the L-G, and three on the N-G leg, and the Tripp Lite distributes them in a four-two-two configuration. The Tripp Lite model puts 200 V varistors on the critical L-N leg with two 470 V as backups after those burn out.

Overall, the APC had a slightly more robust design, but the differences weren't glaring, nor were they decisive in light of its less-than-stellar performance in testing. Comparing photos from the last teardown, we didn't notice any major component changes in the APC from year to year, so we can only attribute the drop in performance to our test unit being on the opposite side of the manufacturing variances this time around.

If you spend a lot more on the Isobar unit, you will get some internal upgrades, like 10 varistors that are each rated for double the voltage of the eight varistors in our picks, and larger capacitors and inductors on the incoming AC line, which provide greater noise and voltage suppression. Because our tests didn't show a huge gain in performance when hit by individual surges, we suspect that the Isobar may keep protecting you for longer, but it isn't necessarily better on a per-surge basis. Because the Isobar units tend to cost more than twice as much, we'd only recommend them if we could confirm they last twice as long, which requires extremely long-term testing.

Best for home theater and office

We picked the Tripp Lite TLP1008TEL because it offers plenty of outlets for most applications, provided solid protection in our testing, and, most important, has the safest failure state of the top candidates.

Most surge protectors continue to provide unprotected power to your connected electronics after their components are no longer capable of blocking a surge, but they give little warning when they do this—an LED may either light up or go dark. Instead of putting your gear at risk, the Tripp Lite safely shuts down all power, letting you know it's time for a replacement. This might be inconvenient on the day that it fails, but it's better than finding out your surge protector failed only after your home theater has taken the hit.

The Tripp Lite had the most consistent performance on all our tests when clamping surges. When testing let-through voltage, it was at or better than average on all three circuit branches. It shares many of the same components with our prior pick from APC, but arranges them in a slightly different design. It also adds two filtering capacitors on the incoming AC line along with additional voltage-suppressing varistors and current-limiting fuses.

The biggest drawback to the Tripp Lite is the lack of rotating or tilting outlets—you get only four of the 10 outlets spaced out well enough to fit large power supplies. Overall, though, it has enough for most home theater and office setups with an outlet or two to spare.

Best for light duty or small spaces

We like the Accell Powramid for light-duty use around the house, even if we hate saying the name. Like our top pick, the Powramid safely shuts down power once its protection is expended, so you won't put your electronics at risk and you'll know when it's time to replace it. In our tests, the Powramid had the most consistent let-through voltage of any of the smaller candidates, averaging 152 volts. The Powramid uses a three-phase varistor design that covers all three legs of the circuit, which is how it achieves its compact size and impressively consistent performance. However, it won't last quite as long as bulkier, multivaristor designs.

The single varistor is also responsible for the near-identical results across all three legs—154 V, 152 V, 152 V. Though the other candidates didn't fare much worse on average, their results were never quite as good, and not nearly as consistent. Accell's Powramid varied by less than 2 V from leg to leg, but the company's PowerGenius Rotating 6-Outlet Surge Protector (with a traditional multivaristor layout) varied by 74 V with a 130 V let-though on the L-N leg and 204 V on N-G. The shorter life of the single varistor in the Powramid is a fair trade for strong, consistent performance in such a small package.

The Powramid's unusual design is actually useful, instead of just a gimmick. All six outlets are spaced and angled in such a way that you could comfortably plug power bricks into all of them at once. Further, it has two USB outlets so you can charge your phone or tablet without needing a power adapter at all. The only flaw in the design is the small plastic cover over the power button that seems made to be lost. But the cover is a bit superfluous anyway, so it's not a deal breaker if it disappears on day one.

Best portable protection

The Tripp Lite SpikeCube is the best protection you can get in a tiny package. It doesn't have a cord and protects just one outlet, but that makes it perfect to plug in behind an appliance or to keep in your bag for when you need to plug your laptop into a strange outlet.

We put the SpikeCube through the same tests as its larger counterparts, and we saw impressive results for such a diminutive gadget. Its clamping voltage across the three legs was just 138 V, 166 V, 156 V—second best on the L-N and N-G lines, and second overall when compared with the other four light-duty surge protectors we tested.

Inside, it's a simple device. Its protective MOVs are about half the size of the ones we found in larger units, providing similar voltage protection but rated to last about half as long. A pair of them protects the main L-N line, and the L-G and N-G lines each get their own. Though our engineer did find a noise-filtering capacitor on the incoming power line, he noted that it was substantially smaller than the one on the Tripp Lite 10-outlet model.

Even though you sacrifice some longevity when you get a surge protector this small, it will still protect your devices from surges just as well as units that are much larger and much more expensive.

For those worried about sensitive electronics

If you want your surge protector to continue passing power even after it fails (like if you have it connected to a device with a hard drive that you don't want to risk damaging with a sudden shutdown), we recommend the Belkin PivotPlug 12-Outlet Surge Protector. Even though it will supply power once the protective MOVs have worn out, it provides above-average protection in an innovative package. You'll just need to check the LEDs on occasion to make sure it's still working, so it's not a great pick if you plan to use it behind a media center.

Our tests showed that in normal use the Belkin's protection was as consistent and as good on average as our top pick—they both averaged 133 V across all three legs. That's likely because each leg uses identical three-phase MOVs, similar to the one inside our other pick, the Powramid.

We especially like Belkin's unique pivot design: Eight of the 12 outlets along the side can rotate up to 90 degrees away from the top plane of the device toward the side. This feature makes it easy to plug power bricks into all eight pivoting outlets, alternating each brick's angle.

The competition

The APC P11VNT3 SurgeArrest 3020J was our previous pick for the best surge protector that supplies power even after the protection has been expended. However, we no longer recommend it for that purpose, as it behaves in a way that doesn't match our criteria. In short, although we still consider it a good surge protector, you may want to replace it if you purchased it believing it wouldn't cut power in the event of its protection failing.

We followed up directly with APC about how the unit behaves once its MOVs have exhausted their ability to block a surge. We found that the device's published specs contradict its manual, and neither correctly describe its behavior: The specs say it cuts off power; the manual says it passes through power.

In truth, it does both. After the MOVs are fried on the main L-N leg—the most crucial power path—the APC will cut power. But if either the L-G or N-G legs' varistors burn out, power continues to flow. This isn't optimal because the device may well leave your sensitive electronics without power—contrary to the reason we recommended it.

We tested the Belkin Conserve because we liked the remote power switch to shut off phantom loads—small amounts of power pulled by supposedly shut-down devices—on six of its eight outlets. However, it performed worse than the three other compact surge protectors we tested and the remote switch proved unreliable in long-term testing and sometimes doesn't respond even after multiple toggles.

The Tripp Lite Isobar HT10DBS costs more than twice as much as our picks and in our 600 V test, the Isobar still let through 144 V, 158 V, and 104 V on the L-N, L-G, and N-G legs, respectively. Overall, this wasn't that different from more basic devices. When we tore it open, we found a few more (and slightly bigger) varistors, along with some upgrades to line filters and related components. In total, the upgrades that you get with the Isobar should make it last longer, but we're still not convinced it's worth an extra $50.