Golf Engineering Associates Technical Help Series

 Rule #1: different types of wire for different jobs. If you try to put any old wire that you have hanging around the shop underground, you may get lucky and your irrigation system will work. Chances are, though, that you will be plagued by short circuits, bad grounding, corrosion or simply a non-functioning system. We outline the most common wire types for landscape irrigation or lighting use below. Remember, when undertaking electrical work of any kind make sure you use common safety sense and don't dive into that 220 volt electrical panel unless you have enough experience not to get electrocuted.

 

Residential & Small Commercial Typical Wire and Usage
Multi-Conductor Sprinkler Wire: For smaller systems, this is a direct-burial cable containing a number of individual copper core wires designed especially for sprinkler systems. Each one of the small colored wires will connect to one of the wires from each of your valves. The other wire on your valves, one from each, should be twisted together and attached to the white wire inside the cable. This is your common ground, and the valves will not operate properly unless this connection is a good one. Attach the other end of the wires to the controller terminals. Remember, this type of wire is for small jobs only - not golf!
Low Voltage Lighting Wire: Small outdoor lighting systems for Res./Comm. use are typically low-voltage and require a two-wire underground cable. The most common mistake is under-sizing. Pay close attention to voltage drop. Any two conductor copper core direct burial wire will work, but lighting manufacturers prefer stranded copper, #12, #10 or #8.
120 Volt Wire:  If you need to run a 120 volt lead from your power source to a controller or other device, make sure that it is a three conductor copper core wire. One wire is "hot" (black), one is neutral (white) and the remainder is the ground wire. The ground will be either green jacketed or bare copper, and once again is absolutely necessary for proper operation. Only direct-burial U.L. listed wire should be used in trenches. When the wire goes above ground, conduit is necessary. Using conduit for direct-burial wire is an unecessary waste.
Wire for Larger Systems & Golf Courses
Solid Copper Core Wire: This is the common wire used for commercial sites, golf course sprinklers, etc. The most common size is #14 or #12 AWG, red jacketed for signal wire and white for the common ground. It's a bigger wire than sprinkler cable (above); therefore it's more rugged and has less voltage loss. Homeowners can use this wire as well, and may have to if there is a long distance (500' or more) from the valves to the controller. It comes in large rolls and can be used for all kinds of different electrical work. In summary, this is a good all-around wire to have around any shop.
120 or 220 Volt Wire for Large Systems: When your power wire routings start getting into the thousands of feet, you have to carefully calculate the power usage of the system, voltage loss and wire sizing. At this level you are still using direct burial power cable, but the sizing can vary greatly depending on how many power legs you have, whether the system is 120 or 220 volt, and how many devices are connected. We recommend that you hire an engineer or consultant to help you with this so that you don't waste money on oversized wire or risk a system that doesn't work properly because of undersizing.	Click above to see a standard voltage loss chart. Total voltage loss should not exceed 10% in the system.
Communication Cable: Each manufacturer of advanced field controllers for large sites/golf courses will have a specification for a particular kind of communication cable. The cable sends command signals between satellites and the central computer controller. Usually this is a heavy-duty pair, in some cases armored with metal to prevent rodent damage.
Other Communication Cables: For pump stations, weather stations, remote telephones, etc. The manufacturers of the devices you are communicating with will have their own spec for communication cable. Pictured here is an underground cable with two twisted pairs. Although most devices require only one pair, this type of cable is often used so that an extra pair is already in the field if you want to connect something to it later. The main cost is digging trenches, not the wire itself, so a good tip is to install a few extra wires at all times just in case.

Valve/Sprinkler Wiring:

Electric valves of all kinds and electric valve-in-head sprinklers operate on 24 volt solenoids. The controller converts it's 120/220 volt input into 24 volts and sends signals via copper core wire to the devices. Whether a homeowner or golf course superintendent, the methods and rules for properly wiring up solenoids is the same. As mentioned previously, every solenoid has two wires: one for the signal wire going back to the controller, the other as a common ground. If you have ten valves in a row, they can all have their common wire spliced together into one common which goes back to the controller. It is crucial that any installer understand how to wire the common ground correctly or else the equipment won't work. The electric anti-siphon valve assembly above is a good example of a neat wiring job. For this assembly four wires are necessary: one for each valve and one for all of their ground wires. The in-ground electric valve at left is single, but we would suggest installing a three or five conductor wire instead of two so that you can add valves later without having to trench in a new wire. Whenever splices are made, make sure to use grease-filled caps designed for underground use. Some of the most common electrical problems in any sized irrigation system are caused by faulty splices. Your super-duper electrical tape job is not going to cut it. Use "direct burial" splices available at any hardware store.  For golf courses, parks or any large system we recommend heavy-duty grease filled splice kits, such as those shown at right. For power wires, use 3M brand Scotchcast 4 resin splice kits which harden into an impervious splice. Always follow the manufacturer's recommendations carefully. Whenever you run wire to an electrical device, leave at least 12" of slack coiled up nearby so that you can come in and do repairs without having to scrounge for every little inch of wire.

Notice the coiled up slack wire, the red signal wire, white common wire and waterproof grease caps in this in-ground installation. If the electric wire and splicing is accomplished neatly with the right materials, you will save yourself plenty of maintenance headaches in the future.