iNavigator 2-Wire System Field Wiring Recommendations

Product / Models Affected:

• iNS2/iDS2 (all variants)
• iN2 (all variants)
• iCCU-S/iCCU-S2
• iCCU-C/iCCU-C2

Wire Recommendations:

• 12/2 IMSA 50-2 Cable:
  • Cable includes a shiels, but connecting the shields is not required/recommended
  • Twisted pair is not required, but would be acceptable
  • Similar cable without the shield and drain wire also be acceptable
• Gauging:
  • #14 AWG solid or stranded wire for installations of 300 feet or less
  • #12 AWG stranded wire for installations of over 300 feet
• Dedicated Pairs:
  • Polara highly recommends dedicated pairs of wires to each button
  • If dedicated pairs cannot be pulled/provided to each button:
    • at a minimum a single pair daisy chained to two buttons on a corner of an intersection typically will work.
    • A 3-Wire cable per corner with the common wire shared by two buttons on the corner will also typically work
    • With either option in place ofdedicated pairs, you may encounter data transmission issues.
• Total run resistance
  • Under 1.5 Ohms (1.5 Ohms or less for total run - from cabinet to pole and back to cabinet). To check, disconnect field wires on both ends; twist the 2 wires on one end & measure resistance of the entire run on the other end.

Recommendation Details

Polara’s iNavigator 2-Wire APS (iN2/iNS2) system transmits power (24VDC) and data (PLC) over a single pair of wires to each button. Therefore, it is very important that the wires be of good quality:

• Wire must be the right size
• Wire must be without stretched sections, kinks, splices, or damaged insulation

These criteria, if not met, can all cause high impedance points that disrupt the transmission of data.

Damaged or cracked insulation can cause stray voltages, which generates noise that impedes data transmission, especially if the wires are next to high voltage wires, or in conduit with water/moisture.

For optimum performance and to help ensure successful installation and operation, Polara recommends the following:

1. Dedicated cable with two (or three for a spare) conductors run from the Traffic Cabinet to each 2-Wire APS button. We recommend IMSA 50-2 cable. This cable includes a shield, but connecting the shield is not required/recommended. Twisted pair is not required, but would still be acceptable. Cable similar to 50-2 without the shield and drain wire would also be acceptable.
2. If the distance from the cabinet to the farthest APS button is:

• Less than 300’ - #14 AWG solid wire should be used
• Greater than 300’ - #12 AWG stranded wire should be used

3. If dedicated pairs cannot be pulled/provided, a single pair daisy chained to two buttons on a corner of an intersection typically works. A 3-wire cable per corner with the common wire shared by the two buttons on the corner also typically works. However with either option in place of dedicated pairs, you may encounter data transmission reliability issues.
4. A common wire for 120 VAC lights must never be used as the button common. Our 2-Wire APS has been successfully installed on 100,000+ intersections. We know that many of these intersections had multi-conductor cables pulled to each pole, and conductors in these cables were used for our buttons. Because high voltage is on some of the conductors in these cables, there is a greater chance for noise that can affect the data transmission on the wires used for the buttons, especially over long runs/distances. The longer the distance to the farthest button, the greater the chance of data transmission problems. Very few installations have been unsuccessful. As long as the conductors meet the recommendations above, a successful installation can usually be achieved, even when providing dedicated pairs of wires to each button is not possible.
5. In the very rare instances where a 2-Wire installation cannot be made to work, installation of 3-wire units is the next best option. Often times when just the farthest button will not operate correctly, just that button (or crosswalk) is used as a 3-Wire.