Q: We have a group reviewing our personal protective grounding procedures, and they are asking if we should be grinding the galvanized coating off towers when we install the phase grounding connections. What are your thoughts?
A: In addition to your question, we also recently received another question about connecting to steel for bonding, so we’ll address both questions in this installment of the Q&A. Your question is about the effectiveness of grounding to towers, and the other question is about the effectiveness of EPZs created on steel towers. We’ll discuss the grounding question first and then move on to the EPZ question.
As to grounding effectiveness, we have two thoughts here – one simple and one that likely will raise more questions than we can resolve in these pages.
The simple thought is this: Consider grounding to the circuit static. It’s difficult to reach but doing so makes it easier to create an electrical connection. Using the system static shares current with adjacent structures and reduces current on the structure being worked. Dividing current among adjacent structures also reduces ground potential’s risks to workers at the foot of the tower. See the following Q&A regarding EPZ if you are grounding to the static.
As to connecting to the tower, grinding off the galvanized coating opens the underlying steel to corrosion and would need to be replaced after the operation. We have asked how utilities make connections and found that most use a flat clamp to a brushed plate or insulator bracket, or a C-clamp to a brushed bolt or step. Either method is a good one. Others follow one of the recommendations in IEEE 1048, “IEEE Guide for Protective Grounding of Power Lines,” 220.127.116.11 for lattice using a ground cluster. The cluster serves two purposes: providing a clamping connection and keeping the clamps close together.
Fortunately, the structure connection can be installed by hand, making the cleaning and mechanical security of the connection pretty reliable. There are several considerations to discuss that should be part of the training provided to lineworkers who make these connections.