At last week’s Connexis Annual Connection, contestants tackled the installation of Wagner composite power poles—lightweight, non-conductive alternatives to traditional wood or concrete structures. Their use sparked an important safety question: Are equipotential zones (EPZs) and cluster bars still necessary when the pole itself doesn’t conduct electricity?
The short answer is yes—equipotential zones remain essential, regardless of pole material. While synthetic composite poles are designed to be non-conductive, the risk to line mechanics doesn’t disappear. Fault currents, induced voltages from nearby energized lines, and lightning strikes can still introduce dangerous potential differences across tools, conductors, and the worker’s body. EPZs ensure that all conductive components in the work area—including the worker—are bonded to the same electrical potential, eliminating the risk of current flowing through the body.
So where does the cluster bar fit in?
Traditionally, cluster bars are used on wood poles to bond the pole itself into the EPZ. This is especially important when the pole is wet and can conduct electricity. The cluster bar provides a central point for attaching temporary grounds and bonding jumpers, ensuring a low-impedance path for fault current to bypass the worker.
On composite poles, however, the pole material doesn’t require bonding. In these cases, the cluster bar may not be needed for electrical safety—but it can still serve a valuable logistical role. It provides a convenient, standardized hub for connecting all grounding conductors and jumpers, helping crews maintain a tidy and effective EPZ setup.
The key takeaway: non-conductive poles don’t eliminate the need for equipotential protection—they simply shift the focus. Crews must still bond all conductive hardware (crossarms, bolts, conductors, tools) and themselves to a common ground. Whether or not a cluster bar is used, the goal remains the same: to ensure that no voltage difference exists across any part of the worker’s body during a fault.
As composite poles become more common in New Zealand’s network infrastructure, it’s vital that safety protocols evolve with them—without compromising on the fundamentals. Equipotential zones are not optional; they are the frontline defence against electrical injury, no matter what the pole is made of.
