Previously, I wrote a briefly about the two components of good landscape lighting. They are the scientific part and the artistic part. The scientific part has to do with all the reasons why electrons do or don’t do certain things. The artistic part has to do with the subtle nuances of which light to use where, what wattage bulb and which lens, if any. In this issue, I want to cover a little history and then get into the scientific or electrical side a little more.
Adding, or even subtracting light from things to increase their perceived value is not new to landscaping. Landscapes have been lit with torches. In fact, certain Roman leaders used people as torches to light their garden parties. Important structures and statues also have been lit with reflected firelight. So, the concept is not all that new.
But, while the concept is not all that new, the low voltage industry that has grown alongside the landscape industry is relatively new. It’s only been within the past 20 or so years that the delivery of low voltage electricity (less than 30 volts) has become the preferred method of illuminating ones personal outdoor space.
There are several reasons for that: First of all, low voltage power is safer to work with. Case in point. Get a line that comes from your low voltage transformer. Strip the insulation from the wires. Now, with the power on, grab one end with one hand and the other end with the other hand. You’re fine. Now, if you were to repeat these steps, simply substituting line voltage 110/120 volts, you would not be fine. Best case scenario, your hair would be much curlier. Worst case scenario, you would no longer need to tend to earthly concerns such as how curly your hair is or isn’t. Please, do not try the above experiments for yourself – just trust me.
Another reason for using low voltage in the great outdoors is because of its simplicity and flexibility. This is a great advantage for design. Low voltage lighting can be run in places that regular house voltage (120 volts) can’t go. For instance, code won’t permit you to run house voltage wires across your lawn at a depth of less than 18”. Although I don’t recommend this, you could do this with low voltage wires and it would be acceptable in the eyes of the law. This possibility alone makes designing and installing your system easier.
Now, just so you don’t begin to think that low voltage is the answer to everything, let me point out a few challenges. Working with low voltage means dealing with voltage drop. In the same way that a sprinkler system requires a certain amount of pressure to function, so does a low voltage lighting system. In fact the whole analogy of water and electricity is a pretty good one. With water, you need a certain amount of pressure. For electricity, this is equal to voltage. With water, you need a certain amount of volume. For electricity, this is equal to amperage. Wattage is a measurement of the amount of electrical work that can be done.
Voltage drop is a natural part of electrical systems but especially low voltage systems because of the way power is delivered. Voltage drop happens when you are trying to run lighting cable too far. For typical 12/2 direct burial lighting cable, this is distances of 50’ or greater. Without enough voltage, your light appears very yellow or orange. The reason it is important to understand voltage drop is because it will affect both the appearance of your lighting installation as well as the longevity of your bulbs. Essentially, using the metaphor of water above, voltage drop is a lack of sufficient electrical pressure to get the job done. This impacts the look and life of your lighting design. Additionally, if your lights aren’t getting 12 volts to them, the life of the bulb can be shortened. This is equally true of giving your lights too much voltage.
The solution to voltage drop is more pressure. This comes in the form of what is known as a multi-tap transformer. This is not your grandfather’s transformer, not even your father’s. These are the transformers that lighting professionals use. You won’t find them at your local mega-hardware store. They are expensive. What they do is provide extra pressure/voltage for longer runs. So, if you find that you started with 12 volts and ended up with 9 by the time you got to the end of your run, you need another 3 volts of pressure. So, you start with the 15 volt tap and when you check the end of the run again, voila! You now have 12 volts to your lights.
Without going deeper into low-voltage electrical theory, there are some important things to take away from what you learned so far. There is a specific voltage range that works best for your lights, between 10.8 and 12.3 volts. Voltage drop happens which means that you will need a multi-tap transformer for any runs greater than 50’. Delivering the correct voltage will keep your lights in the right color range and ensure that they last as long as possible. Of course, now that you know this, you also know that your lighting person should have a voltage meter as one of their main tools for installation. How else will they know when they are in the right voltage range? The answer is that if they don’t have one they won’t. Subsequently, if you hire someone to install your lights and they aren’t using a voltage meter in conjunction with your multi-tap transformer, get someone else.
