Australian Standards – Security Systems – Part 2 EOL Resistor Termination

This post partly relates to the ATMOD a Jack Fuse product that houses End of Line (EoL) resistors on a PCB with quick connect terminals.

A potential customer recently scoffed at the ATMOD claiming it did not comply with Australian standards. Apparently this customer was under the impression that the standards dictate that resistors must be connected via soldering and insulated with heat shrink.

In fact the standard does not directly cover the termination method for EOL resistors. AS/NZS 2201.1 does refer to termination methods in general including crimping, soldering, terminals and self locking connectors. The ATMOD uses self locking connectors. All that is needed to make the ATMOD comply with the termination standards is for the installer to use the correct cable size. (Cable types are stated in the ATMOD data.) Security four core is perfect.

To be fair to the potential customer, I subscribed to the solder and heat shrink method of termination for many, many years and still use it on occasion. Apart from the ATMOD I believe soldering to be one of the better/more reliable methods for connecting EOL resistors inline.

There is one drawback with soldering, the axial resistors supplied with all alarm panels have solid conductors and are designed to be soldered to a PCB with strain relief. Axial resistors were never designed to be soldered in line with a flexible cable in the field and they do break from time to time, especially if twisted together or around the cable.

On a slightly different note, crimping is an acceptable termination method under AS/NZS 2201.1. I believed for years that crimping was not a good termination method. I have in the last couple of years started crimping joins in security cables. I have found crimping to be an effective and efficient means of jointing as long as you have space for the join and it will not be exposed to the weather. I would however never crimp a resistor join as the solid conductor is too brittle. The standard backs this up by stating that only stranded cables are to be crimped. It also dictates that a ratchet style crimper must be used.

Pliers and cheap auto motive crimp tools do make an inferior connection.