In much the same way that the water coming through a faucet often needs to be filtered or purified in some fashion before use, electricity coming from wall sockets can often be optimized by passing it first through a filtering device. Though they do not do exactly the same thing, a power conditioner or a surge protector are two of the common products used to filter electricity. Whether to use a power conditioner or a surge protector depends on the exact qualities of the electricity coming in from the grid, and the real-world needs of the user.
Specifically, the decision surrounding whether to use a power conditioner or a surge protector, or both, depends mainly on the quality of electricity coming in through the sockets of a house. So-called dirty electricity can occur for a number of reasons, from obsolete or damaged wiring to interference from nearby high-drain electronics or lights. Essentially, it is power that suffers from wildly fluctuating voltage. Depending on the device plugged in, this can result in poor performance from a computer, random humming or static in audio players, and lights dimming or burning out prematurely.
In situations where this fluctuation is the case, a power conditioner is beneficial. These devices regulate input voltage and output it at a stable level, most commonly either 50 Hertz (Hz), 60 Hz, or 400 Hz. These are the three most common frequencies used by consumer and commercial electronics. If an outlet, and its associated wiring, is supplying power that is fluctuating from 25 to 70 Hz — something easily tested with a voltmeter — that electricity can be conditioned to a stable voltage before passing it on to a sensitive device.
A surge protector, by comparison, is useful in almost all cases as a preventative device against the damage that can be caused by power surges. Surges can occur as a result of lightning strikes or electric grid malfunctions. Uncontrolled voltage briefly surges through wiring and outlets, many orders of magnitude beyond what most electronics are designed to handle. As a result, computer parts, lights, and almost all other electronic equipment plugged in at the time of a surge may be permanently damaged or destroyed. A surge protector, in such a situation, has redundant circuitry designed to handle the overload, sparing vital components.
So, while at first blush buying a power conditioner or a surge protector may seem like a binary choice between one or the other, they are, in fact, complementary pieces of equipment. Surge protectors should be part of any electronics setup, protecting against dangerous spikes in voltage that can damage sensitive devices. In situations where power is unstable, a power conditioner helps level it out, working in concert with a surge protector to offer the safest, most effective electricity possible.