Power spikes and surges

What causes power surges?

A power surge, or transient voltage, is an increase in voltage significantly above the designated level in a flow of electricity. When the increase lasts three nanoseconds (billionths of a second) or more, it is called a surge. When it only lasts for one or two nanoseconds, it is called a spike.

Power surges occur when something boosts the electrical charge at some point in the power lines. This causes an increase in the electrical potential energy, which can increase the current flowing to your wall outlet.

There are several sources of power surges, externally and internally. A common cause of external power surges – especially the most powerful surges – is lightning. Surges can also occur when the power comes back on after an outage, when a tree branch touches a power line, or a small animal gets into a transformer. Cable theft causes frustrating outages and consequent surges. Apparently there is at least one attempt at cable theft each day in Johannesburg. In all cases, thieves get access to a local neighbourhood sub-station kiosk, either by breaking in or just exploiting damaged locks and open doors.

Power surges can enter a home through several pathways. In the case of lightning, it can take the path of the TV or satellite dish cable, through the incoming telephone lines, or through the incoming electrical service line.

Internal power surges happen dozens of times a day, usually when devices with motors start up or shut off, diverting electricity to and from other appliances. Smaller devices like hair dryers and power tools can also cause problems. More than half of household power surges are internal.

Why do power surges cause damage?

Your home is filled with items susceptible to power surges. Anything containing a microprocessor is especially vulnerable - the tiny digital components are so sensitive that even a 10-volt fluctuation can disrupt proper functioning.

Microprocessors are found in hundreds of consumer items, including televisions, cordless phones, computers, microwaves, and even seemingly "low-tech" large appliances like dishwashers, washing machines and refrigerators.

An increase in voltage above an appliance's normal operating voltage can cause an arc of electrical current within the appliance. The heat generated in the arc causes damage to the electronic circuit boards and other electrical components.

Smaller, repeated power surges may slowly damage your electronic equipment, which may continue to function after small surges occur until the integrity of the electronic components finally erode and your television, cordless phone, or answering machine mysteriously stops working. Repeated, small power surges shorten the life of appliances and electronics. Small surges won't leave any outward evidence, so you may not even be aware they're happening - even though they may occur dozens or even hundreds of times each day.

Large power surges, as with a lightning strike, can cause instantaneous damage, "frying" circuits and melting plastic and metal parts.

What can be done to prevent damage and loss?

• Direct lightning strikes are powerful enough to overwhelm even the best surge protection; therefore the ultimate surge protection is to unplug equipment from the wall if you suspect a surge might be coming.
• Get surge arrestors for the plug points in a home or use a UPS system which ensures the power quality to sensitive devices such as computers and TV's. The UPS option is the most effective, but is also the most expensive. A surge arrestor is cheaper and can be very effective, but also have a limited life which is determined by the number of surges it can prevent before it fuses and becomes useless. You can also install a "whole-house" surge arrestor. You generally install these units near your electric meter, where the power lines run to your building. This protects all the circuits in your house or office from a certain range of voltage surges. Units designed for whole-house protection are generally built for outdoor installation. Better surge arrestors can handle surges up to 20,000 volts while standard outlet surge protectors can't handle more than 6,000 volts. Contact your electrician and discuss a plan to combat power surges.
• Adopt a substation. The key to stop cable theft and to protect your electrical equipment is to identify your nearest electricity kiosk, keep an eye on it and report anything suspicious. Walk or drive past regularly. If you note broken locks, open doors, evidence of habitation by vagrants, overgrown foliage, damaged boundary fences and gates, structural cracks or damage to the walls/roof, rotten woodwork or beehives, report it to City’s Power’s risk management control centre on 011 490 7553 or Primedia’s Crime Line on 32211.
• Make sure that your household and homeowner's insurance cover damage caused by power surges. You cannot claim damages from Eskom, the council or your landlord.

Published in: Linprop Newsletter


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