Transformer Guide

Guide to Multi-Tap Transformers

What is a Multi-Tap Transformer?

We carry a series of transformer that offers a "tap" range of 12-22 volt taps.  The difference between multi-tap transformers and the typical 12v transformer are the additional volt taps offered.  The reason for the extra volt taps is to help eliminate voltage drop by allowing you to access higher volts from the same transformer, which should help regulate the light output/voltage to the lights on a run that experience voltage drop, or in other words, show a weaker light output.  Generally, the fixtures that will show the weaker light output, (experiencing voltage drop) are the fixtures closer to the end of a run.

What is Voltage Drop?

As electrical energy passes along a wire, it loses a little "electrical charge" or voltage the further it travels, meaning that your voltage output will decrease as the distance increases from the transformer.  This is called Voltage Drop.  Lamp life, light output and color temperature are affected by voltage as it is measured at the fixture.  The values for a given lamp are based on a voltage measured at the lamp of 12v (11.8v on some models).  Operating the bulb at any other voltage will change the values of the light bulbs.

The factors that affect voltage drop are the load (wattage), the length of the wiring run, the voltage at the transformer and the size of the landscape cable.  Use the chart below to determine the maximum length of the run at a specific wattage without worrying about voltage drop.

What is the optimum voltage for a landscape lighting system?

Every volt is important on a low voltage system.  The optimum voltage is debatable but most agree on 11.6v being the ideal target.  At this point, you will only lose a small percentage of light output but gain expanded lifetime on the bulb operating life.  

In the off-chance that experience this voltage drop problem, all you need to do is simply switch taps.  The way to switch to access the higher volt taps is easy!  Easily remove the cable connected to the 12v access port's voltage tap, and connect it to the next highest access port's voltage tap in-line until you find the right access port/voltage that will correct for the voltage drop.

How do you access Multi-Volt transformer ports?

The maximum circuit a transformer can have is 300 watts, according to UL standards.  Therefore, a 300 watt transformer will only have 1 300w circuit, a 600w transformer has 2 300w circuits, 900w transformer has 3, and so on.  For example, a 900w transformer having 3 300w circuits, it will then have 3 "common" access ports but only have 1 set of multi-volt tap access ports (depending on the transformer).  The reason for 1 set of multi-volt tap access ports is because they can be shared.  Each port is large enough in size to accommodate up to 6 wires.

So for the sake of the an example, a 900w transformer to power 3 separate runs of fixtures which has a total cost of 900w of power draw.  Split the fixtures so that each run has a power draw of 300w a piece or less.  Testing with the run that would have the highest power draw, place the first wire into the first common access port and the other wire into whatever multi-volt tap access port that you'll need for the run.  For the next run, use the second common access port and the necessary multi-volt tap access port for the run, use the third common port for the third run and the necessary multi-volt tap access port, and so on.  

As an example, if you go from the 12v access port to the 13v access port, and you are still experiencing the problem, then you will simply need to try the next highest access port in line which would be the 14v access port and continue accessing the available access ports on your multi-tap transformer until you have reduced or correct the problem.

Please remember that before you purchase your multi-tap transformer, make sure you purchase the correct unit as we do NOT accept returns on transformers unless defective and under warranty.  We have provided a chart below to help you avoid purchasing the wrong transformer for your application, but please do not buy a transformer SOLELY on the below chart.  Please confirm all this information with an on-site electrical contractor or with us, either over the phone, via email (sales@affordablequalitylighting.com) or with the online chat in the bottom right hand corner of the website.