Spot Versus Group Relamping
There are a variety of reasons to practice group relamping in which a set of lamps is replaced at a scheduled time rather than spot relamping in which lamps are only replaced when they burn out. Most of these reasons apply to fluorescent and high-intensity discharge (HID) lamps rather than incandescents which have much shorter lifetimes.
- Group relamping requires much less labor per lamp than spot relamping. A worker might take as long as a half hour to retrieve and install a single lamp. If all the materials were on hand for a large number of lamps, a worker could move systematically from fixture to fixture and cut the required time to about 3 minutes per lamp. The process would also be less disruptive because group relamping is usually done outside working hours.
- Group relamping is easy to schedule and delegate to outside contractors who have special equipment and training.
- Group relamping provides brighter and more uniform lighting because lamps are replaced before their output has fully depreciated. Direct energy benefits result if the designer, anticipating group relamping, uses a smaller safety factor.
- Group relamping offers increased control over the replacement lamps reducing the chances of mixing incompatible lamps—such as those with different color temperatures.
Economic Comparisons
Economic comparisons typically show that group relamping has higher lamp costs but lower labor costs than spot relamping. One such comparison in Table 1 indicates a 31% overall savings from group relamping. This type of calculation is heavily dependent on the difference in labor costs between group and spot relamping. For example, if the group relamping cost of $1.50 per lamp jumps to $3.50, the balance tips in favor of spot relamping. Remember, however, the noneconomic benefits of group relamping discussed above when deciding between the two methods.
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Last Modified: May 9, 2009
