In general, I’m a supporter of the CGA Best Practices, but I’m relieved to hear that Chapter 4 (Locating and Marking) is under task team review. Of course, before pointing out any problems in the current document, it’s
important to note that there was a time not that long ago when no formal attempt had been made to implement training standards for locating technicians (as Nulca did in 1996), or to identify and publish damage prevention
best practices (as the Common Ground Study did in 1999), and there’s no doubt that the hard work of the volunteers who brought both to fruition has made everyone safer. In the two decades or so that have passed since these initial efforts, Nulca has undertaken three significant revisions to its training standard and a fourth is currently in the works. Large portions of the original CGA Best Practices for Locating and Marking remain in place
essentially as written, however, even though the original best practices were drawn up by a relatively small committee working under a tight deadline.
This is problematic because in the absence of specific statutory guidance, attorneys litigating damage cases reach for the CGA Best Practices document as a reference for what constitutes prudent and responsible field locating, and the current Best Practices’ bias in favor of conductive locating over inductive locating ignores the fairly routine circumstances under which coupler induction is preferable to direct connection and the rarer, but still common, circumstances under which transmitter induction is preferable to both direct connection and coupler induction. To wit:
The coupling clamp can be used to effectively isolate conductors that are bonded in common and which cannot be easily (or safely) isolated from other conductors in a common structure. Best Practice 4.12, which establishes the conductive method as the preferred means of locating, seems to have been written by a committee well-versed in telephone
locating where grounds are easily manipulated, but not so much in cable television or electric locating where they are not. Where three or more conductors are present in a cable television pedestal or an electrical cabinet (transformer, junction box, switch cabinet), the coupling clamp will tend to place the strongest relative signal on the conductor around which it is attached. The clamp is also a more effective means of locating cables coming down poles than is direct connection to the ground wire on the same pole, particularly when multiple utility types are present on that pole. In these situations, the standing Best Practice
could be used to condemn a locating technician who wisely chose the inductive coupler over the less effective direct connect method.
Transmitter induction, while requiring high frequencies and resulting in signals prone to bleed-over, is unique from directing connection and inductive coupling in that it doesn’t require a topside access point to apply signal. This is a crucial strength entirely ignored by the current bias in favor of conductive locating. When locating a transmission pipeline
in a rural area with widely-spaced access points for instance, direct connection might require applying signal at a point sufficiently far enough from the actual dig location as to render that signal all but unreadable by the time it reaches the area where it is needed. A transmitter induced signal applied from a short distance away in these circumstances, far
from any adjacent conductors, would surely be a more preferable locating method. Even in some congested circumstances, limited topside access creates locating problems better solved by high frequency transmitter induction at a more favorable signal application point. Just because a topside access point is available, doesn’t make it the best choice to solve a locating problem. This point can easily be illustrated by visualizing the hub of a wheel and it’s radiating spokes. Locates would likely be more effective on the radiating spokes of the wheel when attacked separately by transmitter induction, than all at once by application of
signal at the central hub, particularly in close proximity to that hub.
I would urge the CGA task team currently working on the review of Best Practices for Locating and Marking to consider changing 4.12 to recognize the situational advantages and disadvantages of each method of signal application. Doing so would free locating companies from having to defend themselves against attorneys who are quick to pounce on inductive locating as somehow reckless and irresponsible, regardless of the circumstances, and wield the current CGA Best Practices as evidence that the only prudent locate is a conductive locate.
Christopher Koch is a training consultant and President of ZoneOne Locating. He is past president of Nulca and worked on both the 2009 and 2015 revisions to the Nulca Professional Competency Standard. He can be reached by email at Christopherkoch@live.com or on Twitter @kochauthor.
The opinions expressed in this article are those of the author. Damage Prevention Professional welcomes and encourages articles and correspondence from all points of view.