The Acclima Communications System
The wiring in Acclima systems not only conducts power to the solenoid valves, but also conducts communications signals from the controller to each device on the system. Sensors receive instructions to take readings, transmit data and perform other tasks; solenoid valves and other devices also receive commands from the controller over the same wires used to carry power to the valves. This dual purpose use requires special attention to Acclima's proprietary 2-wire system.
Existing System Upgrade
The Acclima system is designed to take advantage of an existing valve wire network, provided it is in good condition. Substandard existing wire networks should be replaced. Inspect existing wires for proper gauge, condition and connection. Wire gauge for the CS3500 should conform to the table below. If the existing wire is adequate, the system will function properly. If communications errors are reported on the controller it may be necessary to replace the defective wire segments. Most importantly, be sure that all connections are properly protected by examination to assure there is no corrosion or discoloration at unions, that each connection has a secure wire nut and that each wire nut is protected by a waterproof grease cap. Bare wires in contact with the soil or exposed to moisture can interrupt communications and accelerate corrosion of the wire network.
New Systems
For new construction, the total length of wire in the system is limited to 10,000 feet; the maximum distance from any system device to the controller is 4,000 feet. Wire loops are permissible, but the length of wire in the loop is limited to 2,000 feet.
Wire size is a function of the distance from the valve to the controller and the number of valves expected to be activated simultaneously:
| Maximum Distance from Controller in Feet |
| AWG | 1 Valve
Activated | 2 Valve
Activated | 3 Valve
Activated | 4 Valve
Activated | 5 Valve
Activated |
| 14 Ga. | 3,300 | 1,650 | 1,100 | 800 | 650 |
| 12 Ga. | 4,000 | 2,650 | 1,750 | 1,300 | 1,050 |
| 10 Ga. | 4,000 | 4,000 | 2,750 | 2,050 | 1,650 |
| Recommended Wire Specification |
| The recommended wire specification calls for special irrigation control cable designed to carry data and power consisting of tin-coated copper conductors insulated with polyvinylchloride and having a high density polyethylene direct burial jacket. A common product is "Maxi Pair" cable. |
| Conductor | Insulation | Jacket |
| Soft annealed copper conforming to STM B-23 | Polyvinyl Chloride conforming to UL standard 493 for Type UF rated 60% | Impregnated polyethylene |
Twisted Pairs
For normal installation, it is recommended that paired wire be installed with a 1 in 5 foot twist to reduce the effects of nearby noise sources on communications. This may be accomplished by drawing the wire over the end of the spool or drum so as to cause a twist in the conductor pairs as the wire is placed.
Pest Protection
Where wire network damage from rodents and varmints is a risk, it is recommended that wiring be installed in buried conduit.
Special Conditions
Heavy electromagnetic fields such as produced by overhead high tension power lines or near-by generator, transformers or large pump motors can interfere with data signals and generate communications errors over the cable. In such conditions, it is imperative that the wire receive a 1 in 5 feet twist when installed.
Multiple Controllers
Where multiple controllers are installed, it is not recommended that cables from different controllers be installed in the same wire trench as "cross-talk" from one controller cable to another can occur. In cases where it is impossible to avoid this condition, cross-talk can be mitigated for two controllers by leaving one cable in the trench flat and twisting the second cable. For three controllers, one cable can be flat, the second twisted right and the third twisted to the left.