In this high-bay retrofit application, I will show the cost advantages of removing T-5HO lamps or T- 8 lamps and replacing these
with LED tubes on a one-to-one basis. Replacing a relatively new T- 5
system with LEDs may seem baffling, but when you’re going from
230 watts per fixture to 96 watts – while doubling lamp life and
maintaining brightness – it makes sense to investigate.
If you are unfamiliar with T-bay fixtures, you can find this type
of high-bay lighting in many Sam’s Clubs, Walmarts and Costco
The building in this application had T-bay fixtures mounted over
20 feet high, each with four 54-watt T-5HO lamps per fixture. The
lamps and ballast were consuming about 230 watts per fixture while
providing adequate lighting. The retrofit involved removing all four
lamps and the ballast, which results in an empty fixture with only the
incoming power wires remaining and the empty lamp holders.
Next, the line voltage wires were connected directly to the first
LED tube. Connector whip plugs allow the remaining LED tubes
to be quickly wired in a series. Within minutes you have four LED
tubes mounted where the fluorescent tubes were located. Figure 1
below shows how the LED tubes are connected.
You can also use this installation design to replace 8-foot fluorescent lamps by using a connector whip between two 4-foot LEDs
end to end. In that case, you are going from a minimum of 150
watts (two F96T- 12 lamps) to only two 4-foot LED strips end to
end, which give off enough light and only require 48 watts and no
Aesthetic Benefits, Risks and Downsides
You want to be sure the LED lights aren’t contributing to glare,
although this is not typically an issue in high-bay spaces. You
should test whether a frosted shield or clear plastic is better for
Power whip wires to
incoming line voltage
Plug this end into the LED
unit and it lights up
Jumper whip connects LED
units up to 240;
2" connector whip Magnetize units to fixture –
Ballast-Free LEDs Reduce Energy by 50%
Hole in the middle of the
magnet for a screw if desired
Connect two 4; LED units using the 2; whip to make an 8; and/or a 2; & 4; to make a 6; unit
in High Bays
Existing fixture energy input: 230 watts per four-lamp fixture
LED fixture energy input:
24 watts per tube or 96 watts per fixture
Material cost: $40 per LED tube
Installation: $25 per fixture
Electrical demand cost: $7/k W per month
k Wh cost: 10 cents/k Wh
3,000 operating hours per year
k W SAVINGS PER FIXTURE
= [(0.230 k W/fixture) –
(0.096 k W/fixture)] x [$7/k W x 12 months/year]
= $11.2 per year in demand (k W) savings
k W SAVINGS PER FIXTURE
= [(0.230 k W/fixture) – (0.096 k W/fixture)] x [ 10 cents/k Wh
x 3,000 hours/year]
= $40.20/year per fixture in k Wh savings
The total dollar savings per fixture would be about $50 per year.
However, with such retrofits, you may also want to count the savings
on labor and material for relamping as well as the HVAC savings.
INSTALLATION COSTS PER FIXTURE
= ($40/tube x 4 tubes) + ($25 installation)
= $185 per fixture
= ($185/fixture)/($50/fixture/year in savings)
= 3. 7 years
In addition, there may be current tax and utility rebates that can help
you reduce your payback by 50% or more.
your particular application before doing a whole building retrofit. In
many cases, the LEDs will provide a brighter environment with more
vibrant colors. Some building managers have chosen to retrofit a
six-lamp fluorescent T-bay units with only five LED tubes, which can
maintain the light levels while achieving additional savings.
When the LEDs eventually fail, you will be replacing $40 tubes.
However, material costs for LEDs are likely to be much less in five
years. Even though these LEDs had a five-year unconditional warranty,
it is likely they will last about twice as long as the fluorescent systems.
The ballast-free LEDs also eliminate a potential point of failure.
I am excited about the simplicity that this LED technology provides. It provides good energy savings and short paybacks, as well
as improved lighting conditions. I don’t typically mention brand
names in an article, but if you want to learn about these snap-in
LED tubes, feel free to email me (
firstname.lastname@example.org) and I
will provide the name of the manufacturer. B
Figure 1: Connecting tubes
Connect two 4-foot LED units using the 2-inch whip to make an
8-foot and/or a 2-foot and a 4-foot to make a 6-foot unit.