Power Reducers

Power reducers are a panel-mounted retrofit option for cutting energy costs in a fluorescent or high-intensity discharge (HID) lighting system. They control the voltage supplied to all the fixtures on a given lighting circuit. When voltage is reduced, both energy consumption and light levels are reduced as well. One of the devices' main attributes is that they are panel-mounted and therefore easier to implement than many other alternatives—one need only install a single device at the panel for each lighting circuit rather than, for example, install a new ballast at each fixture.

Power reducers can deliver energy savings, but lighting retrofits often produce greater energy savings with only slightly higher first costs. Potential users should be wary of exaggerated claims for these devices, such as having the ability to cut energy use by up to 50 percent with little or no noticeable loss in light levels. Energy savings of this magnitude will usually be accompanied by reduced lighting levels that are quite noticeable and may affect productivity. However, there are still some niches in which power reducers might provide good value, such as when users desire to shed load in response to utility requests and for overlit spaces with either HID or fluorescent lighting with difficult retrofitting conditions that preclude fixture access.

Manufacturers of power reducers recommend them for illuminating generally wide-open areas in large facilities. These buildings might include large retail outlets, parking garages, warehouses and distribution centers, and large manufacturing plants that use fluorescent or HID lighting systems. The manufacturers also recommend their devices for outdoor lighting in areas such as parking lots or parks. Power reducers are not recommended for individual offices or for lighting circuits with few fixtures.

In addition to energy savings, manufacturers make claims for benefits such as longer lamp and ballast life. Because less power runs through ballasts that are linked to a power reducer, they run cooler and therefore are likely to last longer, although no independent tests have confirmed that effect. Manufacturers also claim that power reducers can lengthen lamp life, but in practice a power reducer might lead to increased or decreased lamp life, depending on specific conditions. For example, in a case where line voltage is higher than nominal or a ballast with a high ballast factor is being used, the power reducer might bring the system closer to its optimum operating conditions and lamp life would be expected to increase (as long as voltage was not decreased too much). In a low-voltage, low-ballast-factor case, the operation of a power reducer might be expected to decrease lamp life. No published data are available about the effects of reduced voltage on the life of HID lamps; however, low voltage can cause a color shift in HID lamps, and specifiers should contact HID lamp manufacturers for information on the effects of low voltage for a given lamp.

What are the options?
How to make the best choice
What’s on the horizon?
Who are the manufacturers?