Welcome to the Mission Environmental Blog

In our business we see a lot of old light fittings – some of them are nearly as old as I am – well ok, not that old! In our experience the major cause of damage to the fittings is heat.

We see wiring that has become brittle and lamp holders that have become so stiff that it’s almost impossible to fit a new tube without a liberal application of WD40.

We recently upgraded a college from T12 to T5 fluorescent lighting. Over 25% of the T12 lamps that we removed separated from the metal end caps as they were being removed from the fitting. The heat produced by the T12 lamps had ‘welded’ the tube end cap into the lamp holder and the glue holding the end cap to the tube had broken down over time. We had to remove the end caps with pliers to get them out of the lamp holders.

It wasn’t a difficult job – just time consuming - and it showed the damage that can be caused by heat. It also meant that each fitting needed to be refurbished, as part of the T5 conversion.

T5 lamps produce a lot less heat than T8 or T12 lamps – at least they do if they have been installed correctly. So one of the major benefits of converting an existing light fitting from T8 or T12 to T5 is the reduction in heat produced and therefore a longer life for the light fitting.

The heat in a wire is caused by the current that is passing through it. The more current that passes through the wire, the hotter it will become. Too much heat and the quality of the wiring will decay and in some cases the insulation on the wire can be ‘melted’ ultimately causing a potential fire risk.

So, as far as we are concerned heat is as much the enemy as power consumption  - we want both to be as low as possible. That’s why its important to know what is happening with regard to power factor correction.

We have seen ‘energy efficient’ products that seem to produce a reduction in the number of watts being used by the fitting, but at the same time, produce a significant increase in the current being drawn. This is being caused by the ‘power factor’ correction.

Most of us learned at school that: Watts = Volts X Amps. The trouble is, like most things, its not quite that simple. The real equation is: Watts = Volts x (Amps X Power factor correction).

The reason that power factor correction tends to be ignored is that its supposed to be as close to ‘1’ as possible. When it is ‘1’ or close to ‘unity’ as it is often described, then everything is fine and watts = Volts x Amps, again.

The problems start when the power factor correction is significantly below 1. If the power factor correction is for example 0.5 – the effect will be that double the current, will be drawn.

This can cause a number of problems. As you know, there is a direct relationship between the current passing through wiring and its temperature – doubling the current will cause a big increase in the temperature of the wire and inside the light fitting itself. The increase in temperature may not lead to a direct fire risk, but it will certainly reduce the working life of the fitting and of the elements inside it.

For a large installation it can also lead to ‘nuisance tripping’ – or the lighting fuses blowing on a regular basis. The solution to this problem is not to fit a bigger fuse – you need to find out what is causing the problem in the first place.

There is a good chance that if you have recently had a lighting conversion carried out and this is happening – that power factor correction is the cause.

We have tested our T5 adaptors in light fittings that don’t have a power factor correction capacitor in the fitting. Typically we measure a power factor of between 0.97 and 0.99 – pretty good!

However, the same T5 adaptor installed in a fitting that has a power factor correction capacitor already will often result in the combined pf value falling to as low as 0.4. Not so good – in fact a major problem.

The solution is simple. If you are using a T5 adaptor check to make sure that there isn’t a power factor correction capacitor in the fitting already. If there is, remove it. It only takes a moment – although obviously the work should be carried out by a properly qualified person.