A second external culprit that can damage or destroy equipment and product is overvoltage. Problems on the utility grid can cause higher than nominal voltages long enough to adversely affect facilities. This situation might happen because of problems with voltage regulation capacitors or transmission and distribution transformers. The utility does have overvoltage protection, but at times these devices do not respond fast enough to completely protect all equipment downstream.

There are two basic solutions to utility-based overvoltage problems, each represents a different philosophy. The first philosophy is to protect the facility from these disturbances at the expense of uptime. In other words, if an overvoltage occurs, shut down the power. This is done through devices that sense the voltage level, and if they exceed a preset limit, they operate, opening the circuit.

The second philosophy is to protect the facility, or at least sensitive parts of it, at the expense of money. This approach maintains uptime while providing controlled voltage regulation. Voltage Regulators are employed to stabilize the voltage under an assortment of power disturbances including overvoltage. Many times, voltage regulation is only one part of a device's capability. An uninterruptible power system, or UPS, is one example. When utility power is available, the UPS regulates the voltage to sensitive loads. Should the source power fail, the UPS provides back up power.

Voltage regulators, or devices that incorporate voltage regulation, may be used at key distribution sites within the facility such as the service entrance, the main distribution panel, or the computer room panel. Typically, however, these devices are small, portable units used to protect one piece of equipment or one sensitive system.