SLC vs LED Tubes

Another option for converting fluorescent to  LED is to replace the fluorescent tube with ballast compatible, tubular LED tubes (aka UL Type A T-LED).  How does this retrofit technology compare against SLC?

T-LED Advantages:

  • Low upfront cost. Short payback period
  • Quick installation if you already have the compatible ballast – simply remove the fluorescent tube and replace it with the T-LED of the same length.

T-LED Disadvantages:

  • Lower efficiency. Actual energy savings are only about 21% for a single tube fixture to about 33% for a 4-tube fixture after taking into account the ballast losses. (For more info please read the energy calculations in this document )
  • Non dimmable. You must size your wattage carefully to prevent overlighting or underlighting problems after the retrofit.
  • Shortened lifespan due to heat trapped within the LED tubes cooking the electronic components all the time. Lifespan is also limited due to fully ON without possibility of dimming.
  • Most T-LED are not compatible with magnetic ballast
  • Most T-LED are not compatible with every kind of e-ballast technologies: e.g. Instant start, rapid start and programmed start. You most likely need to hire an electrician to open the ballast cover and examine if your ballast is compatible with the LED tubes that you have purchased.
  • Require regular replacement of the electronic ballast in the fluorescent fixture which typically last only about 20,000 hours.


Comparison:  Retrofitting a 2-tube 4 ft fluorescent fixture

Hours of operations: 24/7 = 8760 hours per year.
% of time space is occupied: 10% (e.g carpark, stairwell)

Two Retrofit options:

  1. Type A LED Tubes (ballast compatible): 2 x 17W per tube = 34W. Ballast power loss = 5W.
    Total input power = 39W.
  2. SLC: Working brightness @50% = 20W. Vacancy brightness @10% = 4W.
    Average input power for 10% space utilization = 4 x 0.9 + 20*0.1 = 5.6W

Adjustable Working Brightness No Yes
Automatic Dimming when vacant No Yes
Automatic Dimming with Daylight No Yes
Ease of Installation Yes, but only if the ballast is known to be compatible and the lamp holders are still in good conditions Yes – totally bypass ballast and lamp holders
Installation time < 10 minutes < 10 minutes
Tube Lifespan < 50,000 hours 50,000-100,000 hours
Energy used per year =0.039 x 8760 = 342kwh 0.0056 x 8760 = 49kWh
5-year Electricity Cost
= 342 x 0.20 x 5= $342 = 49 x 0.20 x 5 = $49
5-year Additional SAVINGS @$0.20/kWh = $342 – $342 = $0 = $342 – $49 = $293


  1. Compared to 2 x T-LED, retrofitting a 2-tube fluorescent fixture using SLC will save you extra $293 in electricity after 5 years in operation (based on electricity rate @$0.20 / kWh).
  2. LED tubes are either dead or nearing the end of their useful life after 5 years in operations and will need to be replaced, whereas the SLC still have many more useful years ahead due to the fact that 90% of the time the LEDs are operating in dim mode.



For more information about how SLC compares against T-LED with computation details and charts, please download this document: