Should I use Surge Protection for my Home Appliances?

The question whether or not to protect your home appliances with surge protection devices is a personal one, but it is something you should take seriously, especially if you use sensitive or expensive equipment. The cost of basic surge protection or surge suppression is minimal compared to the price of replacing equipment such as audio or video equipment.

Surge suppression really should be used for all electronic devices such as Computer Monitors, Televisions, Printers and DSL equipment. In fact any equipment that is semi-conductor based. The components in some of these devices are very susceptible to sudden changes in voltage, in particular increases in voltage.

So how does surge protection work?

A surge protector is normally placed in the AC power line between the wall outlet and the device it is intended to protect. Some surge protection devices can also be used to protect telephone equipment by being placed in the telephone line. They are designed to protect against what are known as voltage spikes or transients in an electrical circuit that can be caused by many different actions, some of which include:

• Circuit Breakers tripping
• Short Circuits as a result of poor maintenance of wiring or corrosion.
• Power Outages
• Fluctuations in power caused by the power generating company
• Lightening Strikes

Surge suppression devices will generally protect against most of these eventualities, but lightning strikes can produce huge surges in voltage in the order of thousands of volts. Even with surge protection, if there is the possibility of lightning then the equipment should be totally isolated from the mains supply, including the surge protection device. It is worth noting that the lightning does not have to directly strike the power transmission lines in order affect the consumer supply. Other than lightning, surges in peak voltage are usually in the magnitude of several hundred volts and most commercially available protection devices will be designed to protect against power transients in that order.  

A device designed to protect against voltage spikes will have a rated clamping voltage, sometimes know as the let-through voltage. This is the voltage level at which the device will divert the unwanted voltage away from the line. The clamping voltage should be a little more than the required voltage for the devices being protected. Most surge suppression devices will have a clamping voltage somewhere in the region of 330 – 500 Volts, with 330 Volts being very common.

Another parameter to consider when purchasing voltage spike protection equipment is the protectors Joules rating, where a Joule is a unit of energy. The rating on surge protection devices will define just how much energy can be absorbed when a voltage transient occurs, without the device failing.  A properly designed protection device should only absorb a certain amount of energy before failing because by absorbing energy, that energy is dissipated elsewhere in the system. A surge protection device should be designed to fail at a sensible rating, thus dissipating the energy to ground and away from the sensitive equipment. The higher the rating, the better the protection and typical ratings for surge suppression devices designed for the home should have ratings in the order of 200-600 Joules.

The time it takes for the protection device to respond to the increase in voltage is known as the response time. If the response time is too long then the damage may already be done, so look for devices with response times of around 1 nanosecond, which should ensure adequate protection.

Finally, good surge protectors will have an indicator light to give you a visual representation that the device is providing full protection. Most devices will ‘burn out’ after a number of voltage spikes, particularly if those spikes are of a high magnitude because the Metal Oxide Varistor (MOV) component has a finite life. The majority of multi-socket surge strips will still function as a basic power strip without the surge protection after the MOV has failed, but without the indicator light, you would have no way of knowing.

If you currently have no surge protection or are contemplating buying new computer or video equipment then it would be wise to invest in a relatively inexpensive surge suppression device to protect your investment. 

This article on Surge Suppression was written by David Christie, MD at NSTUK Ltd,  Website http://www.ipexpress.co.uk .