T5, T8 and T12 Flourescent Lamps

by Steve on September 12, 2010

Linear Fluorescent Lamps

T5, T8 and T12 Lamps are linear, meaning that they are straight and not 
curved. Most T5 lamps have an average rated lamp life of 20,000 hourswhich is maybe twice that of standard lamps.

The ‘T’ stands for the shape of the lamp- ‘Tubular’.
The number signifies the diameter of the lamp in units of 1/8 of an 
inch (0.125cm). Therefore a tubular lamp mearuring 5/8 of an inch (0.62cm) is a T5.

T8 lamps are 1 inch diameter (8 x  1/8 inch) and T12 lamps are 1 1/2 inches (12 x 1/8 inch).

Energy Saving
T5 lamps are seen as being an economical alternative to the standard T8 lamp however there are some drawbacks.  They cannot be used as direct replacements because they are a different length and Pin Base from standard lamps.  The lamp end caps for T8 and T12 are the same, using what is called a medium Pin Base whilst the T5 uses a miniature Pin Base.  However there are retrofit kits available which can adapt existing fittings to T5.

Lengths of lamp are 2ft, 3ft and 4ft but the actual lengths differ 
within these ranges as follows:
2ft- T5= 549mm  T8 & T12= 590mm
3ft- T5= 849mm  T8 & T12= 895mm
4ft- T5= 1149mm  T8 & T12= 1199mm

T5 tubes are available in Standard and High Output versions (T5HO) and  a like for like comparison against a standard T8 lamp will give around a 20-50% energy saving, although the T5 currently costs more to buy.  T5 technology is still fairly new and lamps such as the T5 Miser linear fluorescent lamps range are being developed to give an even lower energy consumption.

One of the main benefits of a T5 lamp is it’s relatively high light output for its size.  This makes it ideal for display lighting and desktop illumination applications.

T5 in Emergency Lighting
Some T5 lamps are not recommended for use in emergency lighting applications.

Read more about T5 light output comparisons.


{ 1 comment… read it below or add one }

Colin Phipps April 9, 2012 at 17:52

Thanks for a very good blog T5 is the way forward

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