2-Wire or not 2-Wire
Is that the question? 2-Wire adapters give landscape controllers a new lease of life
TODAY’S landscape irrigation controllers have become extremely sophisticated, incorporating microprocessor technology to improve timing and diagnostics. However, as advanced as the technology becomes, it is hard to escape the necessity to connect the controller to each and every valve. More expensive two-wire decoder- based irrigation controllers are used on the larger systems such as golf courses, but up till now, low-cost landscape controllers are still multi-wire. And that can turn into a lot of wire. Unless you are installing valves on a small, regular shaped piece of land, there can literally be miles of buried wire. Worse yet, the arrangement of these wires is usually a disorganised web spread out throughout the site. A contributor to this problem is the
nature of multi-wire controllers, which typically have dedicated wires that connect to each valve they control. Each controller is equipped with a terminal strip that has one common wire and one dedicated wire for each valve. These dedicated wires (up to 48 of them) are
run out to the individual valves. The common wire, on the other hand, runs from valve to valve, throughout the array. In a large installation, there could be well over a mile or so of wire going to a single valve.
In the UK it is common to use multi-
core telephone wire, cutting the outer sheath at each valve position, teasing out the common wire and the correctly coloured wire for that valve. After cutting and stripping, the solenoid wires are carefully joined to the common and valve wire, taking care not to break the quite small copper wires coming out of the multi-core cable. The outer sheath should then be repaired to ensure water does not get into the cable.
In the USA, they tend to use instead an individual PVC sheathed 18AWG wire for each valve plus a common wire that goes from valve to valve. These have quite thick insulation and are buried directly into the ground in a trench. The wires start off each with a different colour but after a year or two in the ground they all look black!
The Story of the Multi-Wire Controller
THIS abundance of wire in multi-wire controller installations causes a variety of problems. One of them becomes painfully apparent when there is an accident with the wire. Say, for instance that you install an
irrigation system that has a whole network - a spider’s web - of wire, buried in the ground. Eventually, the time comes to plant the first of a group of trees. The contractor comes in with a JCB and the equipment makes a nice big hole, perfect for the tree. When the shovel rises from the hole, looking a lot like a dirty pasta fork, there hanging from the shovel is a large clump of wires and it’s obvious that half of them are broken!
This is one of the worst nightmares for a contractor. Before any other planting is done, someone must repair each wire. That requires figuring out which wire goes with which and connecting them. On sophisticated installations, the wires are colour-coded, up to 48 different colour combinations
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68