What does the Alwar oil mill manual say a 28 watt T5 tube saves over a 40 watt tube with a choke?

The Bureau of Energy Efficiency (BEE) Alwar manual puts a 40 watt (W) tube on a choke at 55 W and a 28 W T5 tube at 28 W. It prints a saving of 25 W: 125 kilowatt hours (kWh) and rupees (Rs) 600 a tube a year. A Rs 600 to 700 tube repays in 12 to 14 months.

What the manual compares

• Old: a 40 W tube with an electrical choke. The manual says the choke loses 15 W and puts the pair at 55 W a tube.
• New: a T5 tube of 28 W with an electronic choke, 28 W in all. The manual says it gives 2,900 lumens against more than 2,000 for the 40 W tube.
• Running hours 5,000 a year, tariff Rs 4.8 a kWh, price Rs 600 to 700 a T5 tube. The manual suggests replacing on failure.

The sum, and where it slips

• Printed saving 25 W: 0.025 kilowatts (kW) x 5,000 hours = 125 kWh, x Rs 4.8 = Rs 600 a tube a year.
• The manual's own table gives 55 W and 28 W, which differ by 27 W. At 27 W the saving is 135 kWh and Rs 648.
• One tube at Rs 600 to 700 repays in 12 to 14 months on Rs 600 a year.

The cluster totals do not tie to one tube count

• For all units the manual prints 42,660 kWh, Rs 1.9 lakh, a cost of Rs 3.0 lakh and a payback of 18 to 19 months (3.0 / 1.9 x 12 = 18.9).
• 42,660 kWh at 125 kWh a tube is about 341 tubes. 341 tubes at Rs 600 to 700 cost Rs 2.05 to 2.39 lakh, not Rs 3.0 lakh, and 42,660 kWh at Rs 4.8 is Rs 2.05 lakh, not Rs 1.9 lakh. Rs 3.0 lakh would buy about 430 to 500 tubes.
• So the 18 to 19 month cluster payback and the 12 to 14 month single tube payback come from different counts. Use the single tube sum with your own tube count.

Before you buy

• Count the tubes that burn 5,000 hours or more a year. A tube lit 1,000 hours saves a fifth of the figure above.
• Our note, not the manual's: light-emitting diode (LED) tubes now compete with T5 tubes. Compare total watts including the driver, and the lumens, before choosing.

One tube, the manual's way

• Old 55 W, new 28 W. Printed saving 25 W (the table's difference is 27 W)
• 0.025 kW x 5,000 hours = 125 kWh a tube a year
• 125 x Rs 4.8 = Rs 600 a year. Payback: Rs 600 to 700 / Rs 600 = 1.0 to 1.2 years
• Carbon dioxide (CO2) at 0.675 kg a kWh, the financial year 2025-26 grid factor: 125 x 0.675 = 84 kg a tube a year
• Cluster: 42,660 x 0.675 = 28,796 kg, about 28.8 tonnes

Watts, hours, tariff and prices are the manual's, at its date.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so last year's monthly kWh from your bills is on file to set against the year after a swap. It does not split out lighting, count tubes or measure lux. A lighting sub-meter is custom, on request.

• Alwar 250 and 150 watt HPSV lamp reports
• Bulb and halogen swaps in an Alwar mill
• Translucent roof sheets in an oil mill
• Which grid factor BEE's old reports use
• Carbon calculators

Sources: Bureau of Energy Efficiency and Confederation of Indian Industry, Manual on energy conservation measures in the Alwar oil mill cluster (SAMEEEKSHA), Central Electricity Authority, CO2 Baseline Database for the Indian Power Sector (grid factor 0.675 kg CO2 per kWh, financial year 2025-26)

Last reviewed 2026-11-06. Figures are the manual's, from the Bureau of Energy Efficiency Small and Medium Enterprises (SME) programme, at its tariff and lamp prices. Get a current quote and check your tube count and hours before you rely on a payback.