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.
Consumer
Education & Research Centre (CERC) - Copyrights Reserved 2003.