Choosing the best surge protector for your home

What does a surge protector protect against?

The main task of the network filter is to smooth out the consequences of very sharp voltage drops and eliminate extraneous interference in the network so that the equipment works in the proper normal mode. Where do strong voltage pulses and high-frequency interference come from in the home electrical network? No, they are not supplied by the local power company. They usually occur in our homes themselves, when turning on and off powerful household appliances and power tools — hammers, drills, refrigerators, air conditioners, washing machines and dishwashers, pumping stations, etc. Also, filters, even inexpensive ones, have an automatic fuse that turns off the power to all devices connected through the filter if the voltage / current surges are too strong. This helps to protect household appliances from damage.

How does a surge protector protect

Even inexpensive filters have an automatic fuse, disconnecting power to connected devices

To protect against voltage surges, a varistor is provided in the line filter. The varistor dissipates the energy of a powerful high-voltage pulse, turning it into heat. Usually, the energy of the pulse absorbed by the varistor is indicated in the filter characteristics and is measured in joules, J. The more energy the varistor can absorb, the better. For inexpensive filters, this is usually hundreds of joules, for high-quality and expensive models — several thousand J. And what happens if the pulse is too powerful? The varistor can burn out from overheating. To prevent this from happening, good network filters have a thermal switch that prevents the varistor from burning out. Therefore, when choosing a filter, pay close attention to the maximum allowable energy of the filter input pulse and the presence of a thermal switch, if it is possible to check these technical parameters of the device. Also, if possible, make sure that non-flammable plastic is used for the housing of the device, so that if the filter overheats, there is no fire hazard. This is especially true of inexpensive Chinese filters of unknown origin.

At the same time, the surge protector does not replace the voltage stabilizer! It eliminates very short voltage pulses (on the order of a few thousand volts) and filters relatively high frequency noise. However, the filter does not save with a long-term constant deviation of the voltage up or down from the limits allowed for the operation of the equipment. In this case, the equipment will either work in abnormal mode or turn off.

Do not forget that the filter characteristics claimed by the manufacturer are valid only if the sockets are grounded! Therefore, in old houses where there is no such grounding, the protective characteristics of the filter may deteriorate significantly.

What to look for when choosing a filter

When choosing a filter, you need to pay attention to the power of the permissible constant load.

The first sign by which surge protectors are usually selected is the number of sockets. The more of them, the more various appliances and household appliances can be connected through the filter. Surge protectors are available with 1 to 8 outlets. Single outlet filters such as APC P1-RS, Belkin Home MasterCube 1, Sven UNO, etc. usually inserted directly into the outlet, representing a kind of "adapter". However, usually the "average" filter has 5-6 outlets. This is enough to connect a computer and accessories to it, and there will also be one or two in reserve. The more outlets the filter has, the better. But! When connecting electric kettles, heaters and irons to the filters, remember that filters have a limit on the permissible load!

Permissible short-term impulse noise current passing through the filter varistor can be on the order of several thousand amperes. For example, even an inexpensive surge protector Sven Optima Base 3/3m has protection against current impulses up to 4500 A. However, this value has nothing to do with the rated load current!

The criterion that you need to pay attention to when choosing a filter is the power of the permissible constant load. The active power of the load is usually indicated in kW, apparent in VA (you can learn more about active and passive power from our article "Choosing a Voltage Stabilizer"). Make sure that the total power consumption of the equipment connected to the filter does not exceed its capacity! For typical domestic use, a surge protector with a permissible rated load current of 10 A is enough, which makes it possible to connect up to 2.2 kW of resistive load to the device. These include surge protectors Sven Optima Base 5/2m, Defender DFS 601, Gembird SPG6-B-15 and others. consumes a lot of energy and does not have strong starting currents. Such filters include, for example, the Greenwave Basic 3-5 model.

To make it convenient to use the filter, when buying, pay attention to such an important parameter in everyday life as the length of the power cord. This length is usually 0.5, 1.2, 1.5, 1.8, 3, 4 or 5 metres. Consider this nuance so as not to run later for an extension cord. If you plan to connect the filter to an uninterruptible power supply that has specific C14 sockets, then you will need a filter with a suitable C13 socket, for example Gembird SPG5-X-10G.

By the way, there are filters that can be mounted on a wall or other vertical surface. If this option suits you to save space, pay attention to the presence of mounting holes on the device case.

Additional security features

The surge protector does not replace the voltage stabilizer, it eliminates very short voltage pulses

Some surge protectors have additional equipment protection features. For example, they are able to protect communication lines — network, telephone, television. These filters include APC P5BT-RS, Monster MDP 800, APC PH6VT3-RS, etc. Why do I need to filter interference in communication networks? For example, if lightning strikes nearby, a strong impulse can come through a telephone or television network that can disable equipment. In a computer network, power surges are likely when using equipment or power supplies of low quality, which is not uncommon in our country. There are filters with USB ports, which makes it possible to connect devices via charging via the USB port on the filter without fear of “burning” the ports on the PC board from overload, short circuit, or for other reasons.

Protective shutters on the openings of sockets seem to be a trifle, but they bring undoubted benefits. First, small children will not stick anything into the outlet. Secondly, if the filter is used somewhere in the country, in a country or village house, insects will not be able to enter the device through sockets. Well, in a city apartment, thanks to the curtains, the ubiquitous dust will not be able to get into the filter. Filters with useful protective shutters are Eaton Protection Box 1, Belkin Conserve 2, Eaton Protection Strip 4, EnerGenie SPG5-U-5, Legrand 694614, etc.

Another useful feature of some filters is separate individual on / off sockets. If with a conventional filter all sockets are turned on together with one switch, then everything is much more rational here. You can, for example, disconnect passive equipment from the network that consumes too much in standby mode, while other devices connected to the filter are actively working. There are quite a few filters with separate switching on of sockets: these are Maxxtro PRO-PWS-05K-10F, REAL-EL RS-6 Extra 1.8m, Sven Fort Pro 5m, etc.

Finally, there is such an exotic as surge protectors with remote control. At first glance, this seems like an unnecessary luxury. But for people with limited mobility or disabled people, such filters are a real find.

Filter the interference!