Surge Protection

Virtually every UPS unit suitable for server use includes surge protection. Thus, it is not necessary to use a separate surge protector on a server connected to a UPS. Surge protectors are designed to absorb the high-voltage transients produced by nearby lightning strikes and power equipment. Such spikes can easily destroy sensitive computer equipment.

Because surge protectors help protect computers and other electronic devices, you should connect devices not attached to the UPS, such as printers, to their own surge protectors.

Surge protectors use several devices, usually metal-oxide varistors (MOVs), that can clamp and shunt away all voltages above a certain level. MOVs are designed to accept voltages as high as 6,000V and divert any power above 200V to ground. MOVs can handle normal surges, but powerful surges such as direct lightning strikes can blow right through them. MOVs are not designed to handle a very high level of power, and they self-destruct while shunting a large surge. These devices therefore cease to function after either a single large surge or a series of smaller ones.

Because MOVs eventually fail, you should make sure that you specify only surge protectors that are designed to stop providing power to the outlets when the MOVs have failed. A protection status light is also useful, so you can tell at a glance if the unit is still working.

UL has produced an excellent standard, UL 1449, that governs surge suppressors. Any surge suppressor that meets this standard is a very good one and definitely offers a line of protection beyond what the power supply in your PC already offers. The only types of surge suppressors worth buying, therefore, should have two features:

• Conformance to the UL 1449 standard

• Automatic shutdown of the surge protector when the MOVs have failed, along with a status light indicating whether the device is working.

Units that meet the UL 1449 specification say so on the packaging or directly on the unit. If this standard is not mentioned, it does not conform. You should avoid any unit that doesn't conform to the specification.

Other useful features include the following:

• Double-sided outlet design If outlets are located at both sides of a surge protector, it's more likely that all outlets will be usable.

• Increased spacing for AC/DC converters Many peripherals, such as broadband and dial-up modems and some types of printers, are powered by AC/DC converters (also known as power blocks, or briquettes). Surge suppressors that provide extra spacing between outlets enable all outlets to be used, even when some are occupied by power blocks.

• Surge suppression for data lines If you have an all-in-one or fax machine connected to a phone line, don't overlook the possibility of phone line surges. Phone lines carry power (enabling the phone to be used during a power blackout), so they can also transmit a damaging surge to the modem or the server. Surge protectors with RJ-11 ports provide protection against phone line surges. A few surge protectors on the market now offer surge protection for RJ-45 Ethernet and RG-6 coaxial cables as well.

• Built-in circuit breaker In a unit that has a built-in circuit breaker, the breaker protects your system if it or a peripheral develops a short.

To protect data lines going directly into your server, such as RJ-11 phone, RJ-45 Ethernet, or RG-6 coaxial for video, you should use surge protectors that connect to the data lines. Some UPS units include this feature, either standard or as an option. If your preferred UPS does not, you should look for standalone units available from vendors such as Black Box Network Services (www.blackbox.com), Connect Technologies (www.connecttech.net), and others.