## How To's

How to Choose a Lighting Transformer

Transformers come in various sizes and types, depending on the number and wattage of the lights that will be connected to them. Once you have determined how many fixtures you will be using, and the wattage of each light, you can then determine which transformer to order. To determine the transformer size, add up the total wattage of all the lamps and add 10% more as a safety factor. (Transformer size = total wattage x 1.1) Transformers are also available with various features, be sure to select a transformer appropriate to the intended use of your lighting system. The two main types of transformers are Single voltage and Multi-tap. Single voltage transformers output 12 volts and are appropriate for smaller lighting systems. Multi-tap transformers typically have outputs for 12, 13, 14, and 15 volts, which allows you to compensate for voltage drops in larger lighting systems.

How do I know if I have power to my Transformer?

The quickest way to see if the Transformer is operating properly is to take a Volt Meter or Amp clamp and test the power level at the Receptacle on the face of the Transformer (3). If your Transformer has a Timer, you must remove the timer in order to test the Transformer Receptacle.

Make sure your Volt Meter is set on the 200 V~ setting. On most digital volt meters, this will be two clicks to the right! If you get a reading between 115-125 volts, you will know that the transformer is getting power to it; therefore, the GFCI Receptacle (2) and the Circuit Breaker in the Electrical Panel (1) have not tripped.

If, on the other hand, you get no volt reading, check to see that the GFCI receptacle has been tripped. Note that sometimes the GFCI that protects the circuit for your Transformer is NOT the one the Transformer is plugged into! It may be found in the kitchen, laundry room or other location within the house! If the GFCI has tripped, reset it and test your Transformer again.

If the GFCI is set properly, next check the Circuit Breaker in the Electrical Panel. If tripped, reset it and test your Transformer.

If you have a Receptacle Tester (RT), insert it into the Receptacle in which your Transformer is plugged. The RT will tell you if the wiring from the Electrical Panel to the receptacle is OK or not. If it does not indicate two orange lights, something is wrong with the wiring.

Outdoor Lighting Maintenance Checks

Annual/Semi Annual

The components of the landscape lighting system will require periodic maintenance in order to keep the system operating at peak performance. A professional installer will incorporate a Lighting Maintenance Program into his offering. Maintenance will typically include lamp replacement, fixture, transformer and cable inspection, cleaning and repair.

Lamp maintenance should be performed regularly as voltage to lamps will increase as lamps burn out, thus accelerating the burnout of the remaining lamps. The type of lamps installed and their average lamp life, the operating voltage at the lamps and the length of time each lamp operated each day will determine the lamp maintenance schedule.

Average Lamp Life is based on lamps receiving 12 volts. Lamps fed 11 volts will burn up to 3 times longer. Lamps fed 14 volts will burn out 7 times quicker than normal. If lamps seem to be burning out prematurely, test the voltage at the fixtures to make sure the lamp is not receiving excessive voltage.

Since different lamp types will burn out at different rates, it is best to include a maintenance schedule that will allow for frequent visits.

Fixture Maintenance

Start fixture maintenance by removing lens caps and blowing the bugs and cobwebs out of the lamp and socket housing with compressed air.

Fixture maintenance should include cleaning of lenses and repositioning and/or re-aiming the fixture. As plant material grows, it will become necessary to reposition and re-aim the fixture in order to maintain its function. Be sure to leave extra cable at each fixture location during installation to allow for repositioning of the fixture in the future!

Maintenance can also include the cleaning of powder coated fixtures by spraying them with a Windex-type agent and wiping clean with a damp rag. Clean bird droppings off copper and brass fixtures, otherwise, let them patina naturally.

Uplight Fixture lenses will become “frosted” over time if subject to a continuous flow of irrigation water. Apply “Rain-X” to the lens cover to help minimize the calcification of the cap. If fogged, clean water deposits with Lime Away or Efferdent Denture Cleaner.

Powder coated fixtures should be cleaned by spraying a Windex-type cleaner and wiping clean with a damp rag. Clean dropping off copper and brass fixtures, otherwise, let them patina naturally.

Fixture maintenance should also include the repair or replacement of broken or damaged stakes and mounting options. If repositioned uplight fixtures create “glare”, add a hex baffle to minimize the nuisance.

Straighten all Pathlights. Crooked pathlight fixtures are a visual annoyance!

Transformer Maintenance

If bugs or debris has collected in the Transformer cabinet, blow out the rubbish with compressed air.

Tighten each Common and Voltage Tap Lug as they can vibrate loose over time.

Check Amperage on each Common Lug. (maximum amperage = 25 amps/per common)

Check all switching mechanisms and adjust timers if necessary.

Socket Maintenance

Blow out the bugs and cobwebs with canned compressed air.

Check for corrosion.

Apply a corrosion prevention sealer to all sockets.

If socket shows advanced signs of corrosion, it is wise to re-socket the fixture

Electrical Maintenance

Check and test all GFCI receptacles, receptacle cover plates

Check all visible electrical connections, J-Boxes, switches, etc.

Cable and Cable Connector

Inspect all exposed cable for nicks and wear. Repair or replace if necessary.

Closely inspect cable and cable ties in trees for girdling

If cable ties are used to attach cable to trees, replace ties annually.

Inspect exposed cable for animal damage. Squirrels, rabbits and other creatures are known to chew on cable like licorice!

If cable connections are not fully waterproof, replace with a waterproof connection. Non-waterproof connectors will allow moisture to creep into the copper cable. Eventually, a corrosive build up within the cable will cause increased voltage drop and a dimming of the lamp’s performance!

How to Calculate Voltage Drop For Long Paired Wire Runs

A primary concern when installing lengths of wire is voltage drop. The amount of voltage lost between the originating power supply and the device being powered can be significant. Improper selection of wire gauge can lead to an unacceptable voltage drop at load end. The following chart is designed to help calculate voltage drop per 100 feet of paired wire as a function of wire gauge and load current.

By matching load current (in AMPs) across the top of the chart with wire gauge (AWG) down the left side of the chart, one can determine voltage drop per 100 feet of paired wire run.

NOTE: A paired wire run represents the feed and return line to the load. Therefore, a 500 foot wire pair is equivalent to 1000 feet of total wire.

Example One:

Given a load current of 1 AMP, and using 18 AWG wire, how much voltage drop can we expect at the load end for a 350 foot run of paired wire?

Using the chart, we match the row for 18 AWG and the column for 1 AMP and determine that voltage drop per 100 feet is 1.27 Volts. By dividing the paired wire length by 100, we get the factor by which we need to multiply voltage drop per 100 feet to determine total voltage drop. Therefore, 350 feet divided by 100 equals 3.5. Multiply 3.5 by 1.27 volts drop per 100 feet to get your total voltage drop. Thus the total voltage drop is 3.5 times 1.27, or 4.445 voltage drop for 350 feet.

Example Two:

Given a camera load of 2 AMPs, that is 400 feet from the power source, which wire gauge should be selected to keep voltage drop at the camera to less than 3 volts?

To use the chart, we need to determine what the maximum voltage drop per 100 feet is. We calculate that 100 feet is 1/4 of 400 feet, thus the voltage drop allowed for 100 feet is 1/4 times 3 volts (which is the equivalent of 0.75 volts per 100 feet):

voltage drop per 100 feet = 3/4 = .75 volts per 100 feet.

So, knowing that we can not allow anything greater than a voltage drop of .75 volts per 100 feet, we can now look at the chart and select the wire gauges that will give us lower voltage drops per 100 feet at a 2 AMP load current. In this case, wire gauges of 10 (.40 V), 11 (.50 V), and 12 AWG (.64) will all suffice, with 13 AWG (.80) being a possibility.

Thus, in order to keep voltage drop at the camera to less than 3 volts given a camera load of 2 AMPs and a 400 foot paired wire run, we need to use a wire gauge in the range of 10-13 AWG.

Formula Methods:

These handy equations can be used to determine voltage drop per 100 feet or wire gauge as an alternative to the chart, even for values that are not on the chart. To arrive at total voltage drop, always divide paired wire run length by 100, and then multiply that number by voltage drop per 100 Feet:

1. To determine voltage drop per 100 feet given load current and wire gauge:

VD = Voltage drop per 100 feet (Volts)

IL = Current load (AMPs)

AWG = Wire gauge

2. To determine wire gauge necessary given paired wire length, load current, and desired voltage drop per 100 feet:

With these useful tools, voltage drop problems can be avoided before installation, saving time, money and ensuring a correctly working system.