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Surges Happen! How to Protect the Appliances in Your Savvy Consumer: Surges Happen! How to Protect the Appliances in Your Home
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Questions . . . and answers

Among the questions often asked by consumers about surges, here is a selection of typical concerns and simple answers.

Q -When looking at the devices offered in the store, the packages show specifications and claims that puzzle me. Can you explain?

A's - Here are some typical specifications, and corresponding comments:

Joules -A (simplified) measure of the surge energy that the protector can dissipate without damage to itself. The higher the value, the more energy the protector can handle. Typical values range from about 100 joules, up to 1000 joules or more. Because this joule number is often based on the three combinations of the wiring, many specifications show the total joules rather than a breakdown among each of the three combinations. Maximum surge current (below) may give better information.

Clamping voltage -A measure of the voltage-limiting capability of the protector. An oversimplified perception might be that the lower, the better. Many specifications show 330 volts for this voltage. This number is embedded in the UL standard values, but it is not a requirement. Somewhat higher clamping voltages, such as 400 volts or more, may be sufficient for protecting electronic appliances, and will make the surge protector itself less susceptible to damage from "swells".

Maximum surge current -A measure of the ability of the protector to handle surge current without damage to itself. You will find a range of values from several hundred to several thousand amperes. Even the lower values offered by manufacturers are sufficient for most surges, but a higher value will give you (generally for a slightly higher price) a comfortable margin of peace of mind.

Speed of response -This specification appears on some packages, others do not even mention it. Since practically all protectors use the same kind of technology for the protective components, and their speed of response is inherently adequate for power- line surges, there is no need to emphasize a fast speed of response.

Internal protection -Some packages provide a description of what happens on the load side of the surge protector (cut-off or still powered), should the protective element be damaged by an exceptionally large surge or a long overvoltage. See your choice, "Quit and be protected or continue" -but now unprotected. Some packages also provide a cut-off and reset feature in cases of large swells, protecting the protector itself as well as the load.

Indicating lights -See the discussion of their meaning on page 7. Be sure that you will remember the meaning after you have discarded the package. If a card with explanations is included in the package, save it because the meaning of the light - on or off, and what the difference there is among colors -is not always clear on the device itself. If the protector maintains power on the load side, how often will you look under or behind your desk to check and make sure that the "Protection on" light is still on ?

UL 1449 Second Edition -Some packages show "UL listed Second Edition" rather than the simple "UL Listed" found on others. It shows explicitly that the product has passed the most recent, improved tests for safety. Other standard symbols such as ETL or CSA might be present instead of UL. They all represent the latest testing for safety.

Guaranteed protection -A measure of the manufacturer's confidence in the actual performance of the product. As for all guarantees, do read the fine print.

Q -If I install one plug-in surge protector in one room, are the receptacles in other rooms also protected?

A -Yes, but only to some degree. The wiring in your house is split into several "branch circuits" originating from your service entrance panel. If a surge protector is installed on a particular branch circuit, the other receptacles on the same branch circuit might benefit from it, but that benefit is much less on other branch circuits. To be more relaxed about protection in other rooms, it would be a good idea to install a surge protector for each of the sensitive appliances in the house. This is especially true for the multi-link appliances because of the problem explained on page 12. (See the next Q&A on whole-house protection and Figure 3 on page 19.)

Q -Will a surge protector installed at the service entrance be sufficient for the whole house?

A -There are two answers to that question: Yes for one-link appliances, No for two-link appliances. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be No -but that does not mean that a surge protector installed at the service entrance is useless. An important function of the service-entrance protector is to divert large surges coming on the power line, before they enter the house. A service-entrance surge protector makes the protection by plug-in protectors easier but, as discussed on page 8, installation at the service entrance generally requires an electrician, unless you are a do-it-yourself person and your city code allows it.

Q -Why single out two-link appliances as requiring special protection?

A -A first answer to that question is given on page 12, explaining the voltage difference problem for these two-link appliances. A more technical explanation is also given on page 18, intended for your electrician.

Q -I have heard about surge protectors degrading over time: What about it ?

A -Many, if not all, electronic components will age and have a limited life. The question is really how long a useful life can a surge protector have. Today's well- designed surge protectors might reach their end of life prematurely if exposed to some exceptionally high and rare stress but, for those tested according to UL 1449 Second Edition, the way they fail should not be a hazard. The prevailing opinion among specialists on surge protection is that most of the observed (and quite rare) catastrophic failures of surge protectors are caused by excessively high line voltage that can occur when there is a fault on the power system. Failure from very large surges that might exceed the surge-handling capability of the protector is less likely than failure from high line voltage.

And now, the "bottom line" question:

Q -How much money should I spend on surge protection?

A -It depends on too many factors to give a simple answer. Technology can change, additional features beyond basic surge protection vary, stores offer "specials", and how much margin makes you feel comfortable is an intangible factor. This booklet is not oriented toward rating product performance or prices, but rather toward explaining the principles, so that you can make an informed decision that will give you confidence.

Image of an arrow linking to About This BookNot just power-line surges

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