Most LED Strip lights, Stick on strips ,Enclosed or Concealed Strips will require 12 or 24 volt dc supply. In most cases this supply voltage is critical of longevity of the strip. A stable power supply will ensure the long life of the strip.
It is wrong to assume that by dimming (lowering ) the 240 volt supply to the transformer/driver will dim (lower) the 12vdc supply to the LED Strip. It is wrong to assume you will achieve dimming of the strip in all cases.
Many LED strip power supplies are switched mode regulated power supplies. By dropping the forward (supply) voltage you will make the power supply work harder to maintain regulated 12 vdc output.
As the forward voltage drops the input amps will rise to maintain output. This will stress the components of the power supply beyond their operating parameters and result in premature failure of the power supply.
True LED dimming (assuming the product you are controlling is dimmable) is achieved with a control of both current and voltage. You will need an LED dimming driver as well as the dimmer mechanism to properly control your LED strip.
A true wire wound transformer with a bridge rectifier will do a stunning job when all else fails. These are not as common as they once were.
Not all LED strips are Dimmable and not all power supplies can be dimmed. It is extremely important to understand how much current your LED strip will draw prior to purchase and installation.
If You or your Customer cannot determine the current draw of the strip, delay installation until this can be determined. This is extremely important. This advice applies to both Dimmable and not Dimmable LED strips.
Rule of thumb is; in Domestic work you can load the transformer/driver to 90%, In Commercial work, do not exceed 80%. In Commercial work the Strip may be on for 14 hours a day, heat build up in the transformer/driver must be taken into account.
This article was published on Saturday 26 November, 2011.
