Electric-Light
Senior Member
A set of experiment was conducted in an open and a closed fixture with both standard 32W and the 4' 25W EnergySaver that became available recently.
It will likely follow a similar trend, but the extent of variation depends on each lamp-ballast system and the environment fixtures are installed in. I think this is something you really shouldn't ignore.
When you re-lamp with 25W lamps in place of 32W, the simple guess is a 22% saving.
From the ballast specifications, the power usage should be
75W with two full wattage 32W lamps
58W with reduced wattage 25W lamps
In my experimental setup consisting of GE ballast and Philips lamps in a fixture configured for both open and enclosed, these were the actual power usage:
25W lamps are not significantly influenced by open vs closed.
32W lamps:
Open: 79W Enclosed 71W. 10% drop in power(as well as output & efficacy)
25W lamps:
Open 61.5W Enclosed 60W 2.5% drop in power
If you're using 32W lamps, removing cover increases output, but also increases power by as much as 11%.
Test setup was allowed to cold start from ambient temp of 25?C in an enclosed fixture. The wattage is low with room temperature lamps, but it reaches the max, drops and stabilizes after it is fully warmed up. When the cover is removed to simulate simple strip light, it picks up some power.
In my setup, 25W lamps yield anticipated 22% reduction in an open fixture. In an enclosed fixture, the saving drops to 15%, or only 68% of anticipated saving.
If your facility has a large number of fixtures with missing/vandalized covers, just replacing the covers can immediately drop power consumption by about 10%.
It will likely follow a similar trend, but the extent of variation depends on each lamp-ballast system and the environment fixtures are installed in. I think this is something you really shouldn't ignore.
When you re-lamp with 25W lamps in place of 32W, the simple guess is a 22% saving.
From the ballast specifications, the power usage should be
75W with two full wattage 32W lamps
58W with reduced wattage 25W lamps
In my experimental setup consisting of GE ballast and Philips lamps in a fixture configured for both open and enclosed, these were the actual power usage:
25W lamps are not significantly influenced by open vs closed.
32W lamps:
Open: 79W Enclosed 71W. 10% drop in power(as well as output & efficacy)
25W lamps:
Open 61.5W Enclosed 60W 2.5% drop in power
If you're using 32W lamps, removing cover increases output, but also increases power by as much as 11%.
Test setup was allowed to cold start from ambient temp of 25?C in an enclosed fixture. The wattage is low with room temperature lamps, but it reaches the max, drops and stabilizes after it is fully warmed up. When the cover is removed to simulate simple strip light, it picks up some power.
In my setup, 25W lamps yield anticipated 22% reduction in an open fixture. In an enclosed fixture, the saving drops to 15%, or only 68% of anticipated saving.
If your facility has a large number of fixtures with missing/vandalized covers, just replacing the covers can immediately drop power consumption by about 10%.