Senior Member
A study was proposed by our field engineer modifying a conventional 1x11W CFL mirror optic fitting to LED using 36 nos.

0.2W (SMD 2835) strip LEDs (white) that was procured from open market.

The payback calculation for the same is shown below:

Details11 W36 x 0.2 W
Type of lamp usedCFLStrip LED
Cost of modification using 36 x 0.2W strip
LEDs including LED driver ** (L)-136
No. of Fittings11
Wattage (W)117.2
Operating Hours/ day (h)1414
KWH per day0.1540.1008
KWH per year for 285 days usage4429
Cost per KWH (Rs.)8.48.4
Energy Cost Per Year (Rs.)370244
Lamp Replacement Cost (Rs.)700
Annual Savings per fitting196
No. of fittings that can be modified (n)66
Total savings per year12936
Investment (L x n)-8976
Payback Period0.69years

** Note: Since the modification was done by the maintenance staff at site no separate labour cost is added.


  1. The average service life of CFL is about 8000-12000 hours. As far as 0.2W LED is concerned, the manufacturer claims that it is more than 30000 hours.

1. Partial replacement (in group of 3) is possible in strip LED whereas CFL needs total replacement.

  1. The average LUX measured (@1m above floor level) was 43 for CFL lamp while for this modified LED fixture it is 30.

  1. However, in locations such as restrooms, Toilet lobbies, Fire escape staircase, basement parking areas and all Lift lobbies (except CCTV covered areas) where the lumen requirement is not so critical, this modification can be done.

  1. To assess the reliability of the strip LED, it's driver and the modification work itself, a reasonable observation period of about 3 months may be required.

  1. A study on similar lines will be conducted on 2x11W CFL luminaire also.

Kindly furnish your views.



Senior Member
New York
Master Elec./JW retired
Why the cost for the CFL and $0.0 for the hand made LED?
I always said about 20% savings LED vs CFL and that was a wag.
How can the man power to "make" the lamp not be part of the cost? Compared to open fixture remove, insert new, disposals?
I think if I was looking at a proposal it would need more specific info., my men could be used elsewhere over making fixture/ lamp cobbles with no warranty. Bring me a ready made (in house) lamp with pin ends.LED G23 PL Lamp - 2-Pin
4.5 Watt - 9W CFL Replacement - 450 Lumens - 4000 Kelvin - Plug and Play or Ballast Bypass - PLT 91331
LED G23 PL Lamp - 2-Pin ImageLED G23 PL Lamp - 2-Pin ImageLED G23 PL Lamp - 2-Pin ImageLED G23 PL Lamp - 2-Pin Image
LED G23 PL Lamp - 2-PinLED G23 PL Lamp - 2-Pin