I've read similar recommendations in the past. In my opinion the conclusion is based on several incorrect assumptions:
- Of the four manufacturers systems that we currently have on our bench, none have zone common terminals tied to Earth ground.
- The failure mode assumes that the short will be to Earth ground; this seems unlikely. The metal doorframe used in their example would probably not be bonded to Unified Earth Ground.
- To assume this particular failure condition (zone high shorted after the EOLR) and that the short is to a part of the structure that happens to be at Earth Ground potential and that all of this occurs on a system that has zone common tied to Earth Ground is quite a stretch.
While I don't share the authors opinion regarding the number of security zones "out there that will not work", it doesn't take any longer or cost any more to wire as suggested.
Even if the benefits were overstated, I don't see any reason for not doing it as described. If it detects only one failure out of 500,000, that and the step towards standardization seems sufficient justification.