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For those that don’t know, a power strip is a type of AC electrical outlet that allows plugging multiple devices into one wall outlet. They could be thought of as a glorified cube tap often coming with added features. Essentially, they have rectangular housing with multiple AC outlets to plug devices into. A power cord comes out of the housing to allow plugging it into an AC socket. Power strips can be found locally at home and hardware stores.
Some of the features that a power strip may come with include AC-line noise filtering, AC-line surge suppression, phone-line surge suppression, cable-television coax surge suppression, ground-fault indicator, and ports for charging USB devices. However, one of the big advantages of a power strip is that it can add a circuit breaker to the AC line, although every model does not have one.
A circuit breaker is a device that automatically switches the AC line off if an electrical current over a specified threshold is detected. Laws in many regions require wired structures to have built-in circuit breakers. And most are probably familiar with the bank of them in the breaker box in their own home. Each breaker in the box services a separate circuit in the home such as the kitchen or basement.
One shouldn’t think of the circuit breakers in their home’s electrical system as being so unreliable that a backup is needed. Even in a home with old wiring, a breaker is probably more likely to fail as an open circuit rather than not opening at all when needed. However, as a safety measure, using an additional circuit breaker in a power strip may not hurt. In the unlikely event that the home breaker fails to open a circuit when it should, if a power strip with a breaker is in place, then it would be the last line of defense against what might be a fire catastrophe.
But what’s even more helpful for safety is if the circuit breaker in the power strip trips at a lower current than the circuit breaker of the AC line that it is plugged into. Assuming one doesn’t need the added amount of current for the devices plugged into it, the power strip adds a margin of safety in this case by ensuring that the current drawn from the line is zeroed at a lower threshold should some fault cause this current to rise uncontrollably. The more current that is allowed to flow, the more likely it is for the line to overheat and combust under some fault condition. So in some rare cases, this may prevent a high-level current, such as due to a short circuit, from persisting and causing a fire.
Typically, circuit breakers in power strips trip at 15 amps. Many home circuits also trip at 15 amps. However, some home circuit breakers may trip at 20 amps, or even higher. And even if the circuit breakers in a home with old wiring can be assumed to still work properly, one must do some checking to determine what the circuit-breaker trip current is for each wall outlet needed, assuming one wants to reduce usage of outlets that have a higher trip current. But this may also reduce use of several conveniently located outlets leading one to use longer extension cords, which can be a fire hazard. One could instead plug a power strip with a 15-amp circuit-breaker trigger into any grounded outlet and be assured of a 15-amp current limit for that outlet.
Another issue is that for any home circuits found to trip at a higher current than the power strip, one would still not be certain of the gauge of the wire between the outlet and the home’s breaker—short of inspecting behind the walls. And does the wire meet or exceed electrical code? Is the cable diameter large enough to handle loads up to the home’s breaker trip current? Is the wire insulation worn? Is the cable crimped or routed in a way that might increase heating or cause arcing under a heavy load current? Again, if using a power strip with a breaker that trips at a lower current than the home’s breaker, one is at least reasonably certain that the current limit is no higher than that of the power strip. In some cases, this extra safety margin may be the difference that prevents a fire.
Use of a power strip also has the advantage that if its breaker trips, then only the devices connected to the strip will be powered off rather than the larger AC circuit in the home that the strip is plugged into. This may prevent additional problems depending on what else is plugged into the same wall circuit. As a rather extreme example, suppose a homeowner is ironing clothes or perhaps soldering a broken battery cable back onto their smoke detector. The power then goes out due to a device on another outlet in the same room, which is seen to be emitting a light plume of smoke. The failed device is immediately unplugged and the ironer heads to the basement to reset the home’s circuit breaker.
On the long trip back from the basement, the poor ironer is distracted. What’s not distracting in a modern household connected 24/7 to telephone, radio, television, and world-wide-web networks? For about a half hour, the ironer keeps smelling smoke and wondering why it hasn’t yet dissipated. Luckily, they finally realize that, in the haste of the initial emergency, they left the iron in a precarious position against some flammable material. And when the power was turned back on it began to smolder. Now they were calling 911 and reaching for the fire extinguisher!
Many power strips come with built-in surge suppressors. While circuit breakers work to limit the line current, suppression circuits work to limit the line voltage. For example, a nearby lightning strike may cause the voltage on the AC line to spike wildly. In some cases, voltage suppression circuits may prevent equipment plugged into the strip from being damaged. But there is no guarantee. Some power-strip models have surge suppressors capable of handling more energy (usually specified in joules). The more they can handle, the less likely they will be to fail and allow a damaging voltage level through. But there is still no guarantee.
Some companies provide some type of limited insurance policy to cover equipment damaged while connected to their power strip. One must do more research though to determine the true benefits of such policies. The claims of loss may not always be that easy to prove. But some may like the added assurance despite the greater cost.
If you live in an area with frequent surges or thunderstorms, you may need a more substantial unit with more surge suppression or a UPS (uninterruptible power supply). A UPS is a device that looks similar to a power strip, but is usually larger and far more expensive since it includes a battery-backup circuit. They are useful in certain instances such as for computer equipment, but this is beyond the scope here.
One drawback of suppressors is that if they fail by shorting, the power strip may become inoperative. Unless you are handy with a soldering iron, the cost for repair is likely more than that to replace it with a new one. Worse yet, if the suppressor fails in its normal open-circuit state, then the power strip will continue to function normally—minus the surge-suppression feature. Unless the power strip includes an indicator such as an LED to show that the suppressor is functional, one can’t trust that it still is.
Many power strips do have such indicators, but one must seriously consider that the indicator only means that the suppressor has not shorted out without providing any true measure of whether it will clamp the voltage as desired. All circuits are not designed the same. Another option is to employ separate devices that only perform surge suppression and save costs on the power strip. These suppressors could then be replaced separately as needed.
It’s not inconceivable for voltage suppressors to prevent a fire from starting. However, the low-cost suppression method using varistor components is only capable of limiting overvoltage conditions for a brief period. And the more fleeting the period, the less likely it is for a fire to start. More frequently though, they may prevent sparking, charring and equipment damage from a line surge.
Regardless of any suppression circuit, for strips with a power switch, one has the option to easily flip the power strip off such that all devices are disconnected from the line. It’s not impossible for a line surge to still damage the equipment in this case, but it is much less likely, provided one has a power strip with a label that says it was tested by a third-party lab, such as U.L. (Underwriters Laboratories). So if you aren’t planning to use the devices for an extended period, maybe you’d rather just disconnect the devices by turning off the power strip’s power switch. But make sure there aren’t any devices plugged into the strip that may still be needed, such as a fax machine, answering machine or a clock.
The above step can also save electricity since some devices continue to use power even when their own power switch is off. The amount of money saved is typically small. However, disconnecting unused electrical devices also reduces the odds that a short circuit in a device will cause a fire. Any device connected to the line poses some risk. Why add to the risk when the device is not in use?
It should be noted though that the power strip’s power switch should not be used to cycle the power on or off for all devices at once, since this may create a damaging power surge. Instead, the power switch on each device should still be used as usual. The power strip’s power switch should only be turned on or off when all of the switches on all of the devices connected to it are in the off position. The power strip’s switch still prevents having to unplug each device though to create another layer of isolation. If one did routinely unplug all of the devices, they may eventually break one of the cables causing a fire hazard.
Use of power strips is really a personal decision. Some may find them too complicated to use. The main application though is when multiple devices need to be plugged into one outlet. Each device adds to the risk of mishap. A power strip can reduce that risk by adding a circuit breaker into the power line, and by offering the user the option to easily disconnect all devices when not in use by flipping the power switch off as explained above. These measures may also help protect connected equipment that’s expensive and/or contains sensitive electronics, such as computer systems, especially if surge suppressors are also employed. One must take care not to plug in devices that draw more total current than a power strip can supply. However, this is another safety feature since it helps prevent the user from overloading a single wall outlet, which might also cause a fire.
Like anything else, one can overdo it. For example, power strips should not be daisy chained, especially if they have surge suppressors, as this could pose additional hazards. And power strips should not be used to overload a circuit. In short, a power strip should not create a false sense of security. Electricity is still dangerous and must be respected. But used properly, a power strip can enhance safety rather than reduce it.
There is no set rule for how many power strips a home might make use of or what should and should not be plugged into them. Everything must be considered carefully on a case-by-case basis. But there are some things to keep in mind. For example, some devices such as motorized equipment, compressors, refrigerators, heaters and electric cooking appliances may draw a lot of current and create surges of their own under normal operation. In some cases, this may use up most or all of the power strip’s power budget making use of one impractical. Also, these periodic surges may weaken voltage suppressors, making their use impractical with certain devices.
But there are other factors to consider as well. Suppose you’re in the middle of writing an important spreadsheet document on your home computer for your job and the neighbor’s Saint Bernard, Chewbacca, wanders in and steps on the power strip’s power switch before you pressed the software’s “Save” button. Not only might you lose your work, cutting power abruptly can also permanently damage a computer’s hard drive leaving all of its data inaccessible. Everyone doesn’t have a “Wookiee” in their midst, but mishaps do happen.
In another scenario, suppose your television set is plugged into the same strip as your refrigerator. The television then gets a power surge from the signal feed during an electrical storm and trips the breaker while your asleep. The next day you find that the frig has been off for 12 hours and the gourmet food for your lavish seven-course holiday-wingding later in the day has spoiled.
Even if just the refrigerator is plugged into the power strip, one still has to consider that the power strip’s switch might fail over time causing the unit to thaw. No part is infinitely reliable. Or even more likely, there could be a line surge that trips the circuit breaker and turns the icebox off spoiling your food.
Given the potential for unforeseen problems, one must analyze the advantages and disadvantages in each specific case and decide if the benefits and risks of using a power strip outweigh the benefits and risks without one. Most consumers may not be knowledgeable enough for this task. A power strip may come with additional instructions though to consult on their proper use. The manufacturer may also have a website that provides further guidance. And some may have a customer-support group that can offer additional assistance regarding more-specific situations and applications. Some local fire-departments also offer free home-safety surveys, which typically include checking for overloaded wall sockets.
Generally, regulations have made home electricity safe even without power strips. And one must be aware of the possibility for power strips to fail and be the source of a problem themselves. It is also possible to misuse them. However, it seems that in many cases a power strip could enhance fire and equipment safety with few drawbacks if properly employed. Most consumers may not be capable though of making informed decisions on power-strip usage. But additional education on this and other topics might enhance fire safety.
If you think you might be in the market for a power strip, seriously consider models with a circuit breaker. All are not so equipped. It is also worth considering units whose circuit breaker can be reset. Such units should have a reset button on them for this purpose. Some models have a breaker of some sort but it cannot be reset. This means that if the breaker is tripped the unit is dead and must be replaced rather than just pressing the reset button to restore normal function. Some units may use a fuse instead of a breaker, however, all of these may not allow the fuse to be replaced. And if they do, most consumers may not know how to replace it.
Most may find it a nuisance to have a power strip with a circuit breaker that is not resettable. But one may need to read the package labeling carefully to tell if the model has a circuit breaker and if it can be reset. The cost difference should typically be minimal for one with a reset button.
One must also consider that in the rare event that the breaker trips or the fuse blows, the fault that caused it may still exist. And this would be precisely the time that a breaker or fuse is most needed! Yet most using a power strip without a resettable breaker may choose to do without the strip entirely until their next trip to the store. If instead the unit had a breaker with a reset switch, under a short-circuit fault the user would find that the breaker will not reset thus indicating a potential fire hazard that should be inspected by an expert before any further use of the given wall socket’s circuit or equipment connected to it. So a reset button can enhance fire safety too.
For safety reasons, power strips generally come with a grounded plug and outlets. So there’s not much point in considering models without these safety features. As discussed, a power switch can also enhance safety notwithstanding the Chewbacca scenario described above. But few if any models exclude this, so consumers may not have much choice here.
One should also be wary of the current capabilities of a power strip before use, including the current limit for the breaker or fuse, to determine if it will meet their needs. It is also helpful if the power strip’s cord is six feet to allow some flexibility in placement. At some longer length, cords begin to pose a tripping hazard.
Safety-conscious consumers will probably only want to consider power strips with a third-party rating, such as a U.L. mark, CE mark, or other respected third-party ratings. Due to the potential hazards of fire and electrocution from home electricity, this is not something to casually overlook. If overloaded, a cheap unrated one might melt and cause a fire before it even trips its breaker—if it even has one.
All power strips are not alike. Reach out to the manufacturers for assistance. Do your homework. Reduce your odds of ending up with a setup that lets you down when you most need it.
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