Power Supplies for LED Garden Lights

What is the difference between a transformer and a power supply?

A transformer provides alternating current (a.c.) output of 12 volts; 12v ac from a wire-wound (magnetic) transformer is used to power halogen lights in the Elipta range. A dc power supply provides direct current (d.c.) which is compatible with Elipta l.e.d. lights: use a regulated 12v DC power supply to ensure stable voltage to a group of Elipta l.e.d. Lights. The power supply should be installed close to the lights as long cable runs can induce instability in l.e.d. lights run from a dc power supply. For larger l.e.d. installations, a 12v ac wire-wound transformer may be used provided it is loaded to at least 80% of it’s nominal rating, eg 32w on a 40va transformer. Electronic transformers should not be used with l.e.d. lights and lamps.

What size of power supply do I need for l.e.d. lamps?

First you need to look at each group of led garden lights, or garden lights fitted with l.e.d. lamps: Then it is simply a matter of multiplying the power consumption in watts by the numbers of l.e.d. lights or lamps to be connected to the power supply, as shown in the examples. Consider some spare capacity within the power supply rating to allow scope to add a light in the future: dc power supplies provide a regulated output voltage, avoiding “overvoltage” which causes premature l.e.d. failure.

- Multiply the lamp wattages for each type of light or the l.e.d. power consumption as shown in the examples below

- Power supplies are available in several sizes starting at 10w - choose the next step up from the total wattage you have calculated

- You can use a 12v wire-wound transformer, which is less expensive than a power supply, but only if the total load of l.e.d. lights and l.e.d. lamps is at least 80% of the transformer rating you propose to use

- Do not use a big transformer with only a small load as this will result in “overvoltage” and cause premature l.e.d. failure

- For l.e.d loads of less than 8w, always use use a 12v dc power supply rather than a transformer

- Do not use an electronic transformer with Elipta l.e.d. products

- Do not use constant current l.e.d. drivers with Elipta l.e.d. garden lighting products

 

led lights Number of lights (W) Power consumption Total wattage   Lights with led lamps fitted Number of lights (W) Power consumption Total wattage
Navigator MInor 10 0.5 5   3w MR16 4 4 16
Navigator Major 4 2 8   5w MR16 4 5 20
Total 14   13   Total 9   36
Spare capacity     2   Spare capacity     4
Power supply rating   (B9403) 15   Transformer rating     40
Power supply loading     87%   Transformer loading     90%

 

Copyright 2014; Information based on products supplied by Lighting for Gardens Limited and is advisory only. The company accepts no responsibility for incorrect use or application of information given. Light fittings can become hot in use; exercise appropriate precautions. Exterior electrical installations should be undertaken by a qualified electrician.