Modern home entertainment and audio equipment can be expensive to replace if anything goes wrong with it. Most people probably never give a thought to protecting it from power surges on the electricity supply lines, or worse still, from lightning strikes during a storm. A single surge protection plug that costs on average between 4-7 can protect equipment worth hundreds or thousands of pounds. A 4-way surge strip with 4 AC Outlets can also be bought for as little as 5 or 6, so it makes sense to make a small investment to protect against electrical damage to expensive items.
The function of a surge suppression or surge protection device is to detect and act against harmful surges in voltage on your mains power supply. These sudden increases in voltage are often referred to as voltage spikes, and can occur at any time. Good surge suppression devices will direct any excess voltage harmlessly to ground and away from the connected equipment.
Any surge protection product will have a joules rating to indicate how much energy the device can absorb when a power spike has been detected. Most commercial surge suppression products will have a joules rating measured in hundreds or thousands of Joules, and even with a simple surge plug you should be looking for a rating of at least 200 joules and preferably over 1000 joules.
The common method employed by these devices to absorb the excess energy is by means of an MOV (Metal Oxide Varistor), which comprises two semiconductors that have a variable resistance. When the voltage increases the resistance decreases, thus providing a path of least resistance to ground for voltages in excess of what you would expect from a good power supply.
A surge protection device will be designed to direct energy to earth when the voltage reaches a certain level, and this level is known as the Clamping Voltage. For a 240v supply, this voltage will normally be something over 300 volts. Additionally, the time it takes for the surge suppression device to recognise and act upon a voltage spike is known as the response time, and although some manufacturers quote this time on their product literature and packaging, in reality a surge device utilising an MOV will always have a fast response time because that is the nature of an MOV.
Replacing ageing multi-socket power strips should become a priority if you consider your home entertainment, audio equipment or networking equipment to be important. Surge suppression strips are relatively inexpensive and will give peace of mind that when a power spike occurs, your equipment will provide the necessary Surge protection.