Determining if a POPIT is Faulty
POPIT Installation Guidelines
First Verify Earth Ground to the Panel
Wire Worksheet Instructions
The following tests make up the Point Validation Process, which allows the on-site Technician to isolate causes of “Missing” point conditions.
IMPORTANT! You must include all data wiring going from the panel that shares a common connection with the point bus. For example, whatever terminals the point bus uses requires all wires on that terminal (i.e., D8112 keypads from Data In terminal) to be tested. They are all possible noise conductors.
TEST A: Wire Identification Method
(This is more of a “process” than it is a “test”.)
Purpose: Before you troubleshoot “Missing” points, you should identify which points are connected to which (of 6 possible) data loop pairs. You may, after comparing the history of missing points verified by the panel’s memory logger and by central station receiver records with a confirmation of which points are connected to which pairs, narrow (divide and conquer) the troubleshooting effort down to one wire pair instead of six.
Desired Results: All wires identified and labeled by function [e.g., “ZX1, Loop 1 of 3”]
TEST B: Earth Short Validation
Earth Short Validation is used primarily to ensure that the wires are isolated from other objects (Water, Metal) that are referenced to Earth Ground. This is a good test for underground cables and inter-building connections to determine differential grounds.
Use CAUTION when working with wires and Voltage
Set Up: Disconnect the wires from the panel before taking the reading.
Meter Setting: 0K to 10k ohms
Lead Placement: Black: Earth Ground wire to panel. Red: Data loop wiring.
Desired Results: A reading of Infinity between data wires and the earth ground wire. Any resistance reading indicates a wire in not ground-isolated.
Symptoms: The system will be experiencing missing conditions, missing alarm and hot resistors on the D8125 if there is a short on the loop. “Runaway” (repeated “Missing”/”Restore” reports), typically related to a single data loop pair (unless, for example, the entire building has been flooded).
TEST C: Conduit Short Validation
(If no conduit on premises, skip Test “C”)
Conduit Short Validation is used primarily to ensure that the wires are not shorted to the electrical conduit and will also indicate if the wiring is shorted to the building conduit since, in most cases, the conduit is strapped to the building frame somewhere.
Set Up: Disconnect the wires from the panel before taking the reading.
Meter Setting: 0K to 10K ohms
Lead Placement: Black: Electrical conduit screw/clip. Red: Field wiring to the devices.
Desired Results: A reading of Infinity between the field wiring and conduit reference.
Symptoms: The system will be experiencing missing conditions, missing alarms, and hot ceramic resistors on
the D8125 if there is a short on the loop. In addition you may be able to relate “Missing” conditions to occasions when the Public Address (PA) system, or similar devices which can feed noise back into nearby AC conduit and spread it throughout the building, are activated.
TEST 😧 AC Noise
AC Noise is very common throughout any building and will usually not be a sufficient problem in and of itself to cause “Missing” points if other noise issues are minimized.
Set Up: Disconnect data wires from the panel before taking the reading.
Meter Setting: 0 to 12 VAC
Lead Placement: Black: Common of panel. Red: Field wiring to data devices.
Desired Results: 0 Volts. Any voltage indicates that a potential source for power surges exists.
Radionics’ systems have worked with up to 10V transient AC on the data loops; points were not reported
“Missing” until devices on the AC circuit were switched on.
NOTE: If you have a data loop with points that are functioning properly, compare it to the data loop on which points have been reported “Missing”. If transient AC voltages are identical, you have confirmed that the existing AC – in and of itself – is insufficient to cause “Missing” points; otherwise, both loops would reflect such a history. That you have two choices with respect to the “problem” data loop: Isolate and correct the other cause, so that the loop can function despite the AC, or; isolate and correct the transient AC source, with the likelihood that the loop can then function despite the other cause(s).
Symptoms: The system will be experiencing erroneous missing and trouble conditions and false alarms. Multiple service calls will result even after replacing equipment. There may be runaway points at certain times of the day, which are often easy to isolate (e.g., points go missing when the chicken feeder augers turn on). The pattern may be broader: Points only go “Missing” while the system/area is disarmed; never when armed or when no one is at the site to switch the powered devices on.
TIP: Reverse Method: Placing the black lead and the field wiring and then touching the transformer terminal should result in 0 VAC.
TEST E: Capacitance
Capacitance is one of the most confusing and hardest to isolate of all the noise issues. It is also rare. A capacitance problem is related to long wire runs or wire runs shorted to a conduit (where the conduit is actually adding capacitance and being inadvertently used as a carrier since it is shorted directly to the wire conductors). Most of the time, if Test A, B, C, D and F are completed properly this test will not be necessary. Capacitance is also increased when shielded wire is used and the wiring is run with other wires in a conduit.
Set Up: Disconnect the wires from the panel. Use a valid capacitance meter.
Meter Setting: 0 to 10 microfarads.
Lead Placement: Black & Red across each data loop one at a time. Add readings from all loops to calculate total system capacitance.
Desired Results: 0.4 microfarad maximum.
Tip: Group the POPIT’s to reduce data wire. Use a low capacitance wire on long wire run applications.
NOTE: Wire up a panel in the shop prior to installing. Connect the wire reels together and do a pre-test on the emulated wire run. Review the Wire Specifications guidelines on Page 3 to calculate capacitance.
Symptoms: Points 101 (ZX1), 109 (ZX2), and 501(ZX2) on a D8112 are the most vulnerable to capacitance, as these are the first "addresses" to “start up.” In a capacitance scenario, three or four points go “Missing”; all except one [101, 109 or 501] immediately restore. That single point may restore only after several minutes, hours, or days. Extra points “Ghost” points are typically caused because capacitance affects the timing of legitimate point responses. There is a random frequency and pattern of the symptom. Common denominators: Shielded wire with drain wire grounded, and long data loop(s) run in conduit.
TEST F: Data Loop Resistance
Set Up: Disconnect data loop wires from the panel before taking the reading.
IMPORTANT! Place a jumper across the data loop terminals of the last device on each data loop so that only the wire resistance is being read.
Meter Setting: 0 to 50K ohms.
Lead Placement: Black: Data out to data devices. Red: Data in from Data devices.
Desired Results: 1 ohm per 1000 feet of data wire.
Symptoms: Low voltage at the last point(s) on the longest data loop. High voltage but low currents due to the high impedance open. “Missing” point conditions due to high resistance.
Pattern: The most distant points are consistently those that go “Missing”.
Suggestion: Keeping Ohm’s Law in mind, it may be simpler to supplement the panel’s Auxiliary Power output than to clear resistance in the data loop wiring.