36W Tubelights tested Which is the best?

INSIGHT – The Consumer Magazine (July-August 2007), published by Consumer Education and Research Society (CERS), Ahmedabad, carries the findings of its in-house comparative product testing laboratory on the extended life test of 7 brands of 36W Tubelights. It has recommended Bajaj, Osram, Surya HBT Slimlite as the ‘Best Buys’. All 7 brands tested are sold countrywide.
INSIGHT – The Consumer Magazine (July-August 2007), published by Consumer Education and Research Society (CERS), Ahmedabad, carries the findings of its in-house comparative product testing laboratory on the extended life test of 7 brands of 36W Tubelights. It has recommended Bajaj, Osram, Surya HBT Slimlite as the ‘Best Buys’. All 7 brands tested are sold countrywide.

Tubelights, technically referred to as tubular fluorescent lamps or TFLs, are bought and used by all sections of consumers. They are available easily in most shops selling electrical products and accessories.

Earlier, we had tested the same 7 brands of 36W tubelights as per IS:2418 (Part-1 to 4)-1977 up to a life of 2000 hours. Samples of all the 7 brands had then conformed to the Standards.

Testing Extended
As per the Standards, tubelights should be tested up to 70 per cent of their rated or declared life to assess their rated life. Though it was not mentioned on the tubelights or their packing, CERS’ correspondence with manufacturers revealed that the rated life is 5000 hours. Hence, the lab tested the samples up to 3500 hours as per the “scope” of IS:2418 part-1-1977 (amendment no. 3). Again, to provide information to consumers, the lab tested them right up to their rated life, i.e.5000 hours, which is not prescribed in the Standards. Brands that work up to 5000 hours should last about two-and-a-half to three years at an average use of five hours a day.

Test Parameters
We tested 10 samples each of 7 brands of tubelights for two IS parameters, one BEE parameter and four additional parameters. The tests were in two parts – the first up to 3500 hours and the second up to 5000 hours.

The two IS parameters were : life test up to 3500 hours, i.e. how many tubelights of each brand continued working up to 3500 hours; and average lumen maintenance (light output) at 3500 hours. The light output of a tubelight decreases with its use. It is not enough that the samples continue working, they should also provide adequate light. Lumen (light output) maintenance is a measure of the amount of initial light output maintained by a tubelight during its life.

Efficacy is a measure of energy efficiency and is defined as the light generated in lumen per watt of electrical energy input. Average efficacy at 3500 hours is one of the parameters considered by the Bureau of Energy Efficiency (BEE) in its criteria for star labelling of tubelights (rated up to 40W). The tubelight showing the highest efficacy is one that gives the maximum light and consumes the least amount of power.

With the objective to provide more information to the consumers, four additional tests were conducted on the tubelights. These involved life test up to 5000 hours, i.e. how many tubelights of each brand continued working up to 5000 hours; the average lumen maintenance at 5000 hours; average efficacy at 5000 hours; and the number of tubelights that showed the blackening of the ends.

Life of the tubelights
Out of the 7 brands, all 10 samples of four brands worked satisfactorily up to 3500 hours. One sample each of Wipro Slimlite (3040.57 hrs) and Anchor Slimline (2800 hrs) stopped working before 3500 hours.

Lumen Maintenance
The lumen maintenance was checked at intervals after 2000 hours – at 2800 hours, at 3500 hours and finally at 5000 hours. As per the IS, the average lumen maintenance at 3500 hours should not be less than 80 per cent of the initial lumen. All the brands conformed to this parameter.

The percentage average lumen maintenance at 3500 hours was found to be the highest in Bajaj at 88.11 per cent followed by Anchor Slimline at 87.76 per cent. Wipro Slimlite recorded the lowest at 82.68 per cent

5000 hours
We tested all 10 samples of five brands and nine samples each of Wipro Slimlite and Anchor Slimline for extended life test up to 5000 hours. All 10 samples each of four brands worked satisfactorily up to 5000 hours with the average lumen maintenance more than 80 per cent. These were Surya HBT Slimlite, Crompton Super Saver XLR-36, Bajaj and Osram.

In the remaining two brands, only 9 out of 10 samples each of Wipro Slimlite and Anchor Slimline worked up to 5000 hours.

Both at 3500 hours and 5000 hours, the average lumen maintenance was found to be highest in Bajaj and the lowest in Wipro Slimlite.

Efficacy
The initial ideal efficacy (initial rated lumen divided by initial rated wattage) is 68.05 for 2450 rated lumen and 67.36 for 2425 lumens. Efficacy decreases with age and use

At 3500 hours, average efficacy was found to be the highest in Bajaj with 59.33, followed by Osram at 57.96. Wipro Slimlite showed the lowest average efficacy at 52.81.

At 5000 hours, the result was the same with Bajaj showing average efficacy at 57.16, Osram at 55.66. Wipro Slimlite had the lowest efficacy at 50.94.

Blackening of Ends
The blackening of the ends indicates that the life of the tubelight may gradually come to an end. Besides, the blackening of the ends is not visually appealing.

None of the 10 samples of any brand tested showed the blackening of the ends even at 5000 hours.

BEE’s Star Labelling Programme
The Bureau of Energy Efficiency (BEE) has developed an energy labelling programme which will be used to rate tubelight brands. Under the programme, tubelights would be rated on a scale of 1 to 5 stars with most efficient product carrying a 5-star rating. Many of the tubelight brands are provided with star labelling.

CERS conveyed the test findings to the manufacturers for their views and comments. They received the results of their own products only.

Anchor and Surya thanked CERS for conducting the test. Osram informed us that its internal reports matched our test results. Crompton provided us an explanation on its claim of extra life ring, extra life and extra light and extra efficacy. According to Crompton, an extra metallic ring improves lumen maintenance and lamps having such rings have life higher than the ones without the rings. Moreover, compared to a 40W tubelight, a 36W tubelight consumes 10 per cent less energy. It also claimed that the savings by replacing a 40W tubelight with a 36W one would pay for its own replacement. In response, Insight contends that all the brands tested had a life of 5000 hours and that Crompton has compared light output and efficacy of its 36W tubelights with its 40W tubelights and not with other brands of 36W tubelights. Since efficacy is ratio of rated lumen divided by wattage and as the wattage consumption is less in 36W tubelights with the almost equal light output (compared to 40W), the efficacy has to be more.

Bajaj and Wipro did not respond till the time of going to press.

Before the publication, CERS had conveyed the test findings to the manufacturers for their views and comments. They received the results of their own products only. None of the manufacturers’ responses was received till the time of the magazine’s going to press. Shaan and Ashok did not indicate any contact details.

Date : 23/07/2007
Place : Ahmedabad

Pritee Shah
Editor
INSIGHT — The Consumer Magazine

Annexure : Table on Rating, Ranking and Best Buys

Brands Tested
The 7 brands tested for extended life were Philips Slimlite, Surya HBT Slimlite, Crompton Super Saver XLR-36, Wipro Slimlite, Bajaj, Anchor Slimline, and Osram.

Standards
We tested the brands for extended life against IS:2418-(Part-1)-1977 (amendment no.3).

Neither the Quality Control Order nor the mandatory certification of the BIS covers tubelights. However, all the brands tested carried the ISI mark. Therefore, they were required to comply with all the IS parameters.