Group Relamping & Maintenence vs. Spot Relamping

Posted Friday, December 21, 2001

Group relamping is one of the most important aspects of lighting maintenance. Based on careful planning, scheduled group relamping involves calculating the average rated life and the average output of the lamps in your fixtures.

While spot relamping (one-by-one, as lamps burn out) is an alternative approach, it can be up to five times more expensive than relamping on a regular basis and, it does not offer the efficient utilization of maintenance labor that is standard with group relamping.

With group relamping, all the lamps in a given area are replaced at a scheduled time. This method is actually the most effective and least cost-intensive approach. This procedure often includes the repairing or replacement of defective parts in the fixtures such as sockets and ballasts. It also includes washing and cleaning the reflective surfaces and lenses.

When performed during off-peak hours, group relamping creates less inconvenience and disruption. Your lighting maintenance is a budgeted, controlled and most importantly, predicted expense. And by taking advantage of large quantity lamp discounts, you can save on the unit price of the lamps. And, group relamping ensures that you get the most footcandles for your energy dollar and that your lighting costs always meet your lighting specifications.


Typical Fluorescent Lamp Mortality

Typical Life Expectancy or Mortality Curve for Fluorescent Lamps
Lamp Mortality Graph



Labor cost to group relamp 800 lamps (every 4 years or 2 times over the 8 years). Group replacement time of 5 minutes per lamp (significant gains in efficiency due to replacing all lamps in each fixture in an area at the same time). Utilizing in-house loaded labor rate of $14.00/hour. Labor cost over 8 years will total (includes 4% inflation):


Labor cost for spot replacements after a group relamp 80 lamps over 8 years at the 20 minutes per lamp will cost (includes 4% inflation):


Lamp cost to group relamp (2 times) and spot replacements over 8 years 1680 lamps. Total cost (includes 4% inflation):


Supervision, ordering, inventory, etc. approximately 5% of total labor and material cost (again, efficiencies obtained and lower day-to-day activities and inventories):



$4,890.00 (or $610.00/year average)



Labor cost to individually spot replace 800 lamps (over 8-year period). Replacement time of 20 minutes per lamp (includes time to get ladder and lamp materials from stock room). Utilizing an in-house loaded labor rate of $14.00/hr. Labor cost over 8 years will total (includes 4% inflation):


Lamp cost to individually spot replace 800 lamps at $1.30 each. Total cost over the 8 year period (includes 4% inflation):


Supervision, ordering materials, inventory cost, etc. approximately 10% of labor and material cost (stated above):



$6,045.00 (or $755.00/year average)



Group Replacement Cost (Over 8-Year Period) $4,890.00
Spot Replacement Cost (Over 8-Year Period) $6,045.00
NET SAVINGS (Over 8-Year Period, 20%) $1,155.00

For analysis purposes. The previous comparison is based on a typical medium size retail location as follows;
Typical location: Number of Lamps - 800 ea. F40/CW/SS
Annual operating hours: 5040 hours (14 hr/day x 360 days/year - includes 1 hour before and 1 hour after open.