Tag: Q & A

Q: Why are communications systems bonded to a utility system neutral? Doesn’t that make the communications messenger a parallel neutral path? A: Yes, it does, but this is a case of “Which is worse?” There are a number of things we do for one purpose that create hazards for another. We must know the issues and choose what we will do. Down guys are one example. In transmission and distribution, many utilities install insulators in the upper section of a down guy to isolate it from the electrical environment at the top of the pole. The purpose is to protect the public from the potential of a hot...

Incident Prevention magazine still receives many questions about the different facets of equipotential bonding. In this installment of Q&A, we provide detailed answers to several of the most frequent questions in an effort to help the industry better understand and resolve these issues for the safety of their workers who use temporarily grounded systems. Q: We have heard that we should be bonding baskets to the grounded transmission or distribution bus to equalize voltage differences between the basket and grounded phase. The idea of using a jumper bond from an insulating aerial lift to...

Q: We are contractors with a truck grounding question for work inside substations. Working within a proper clearance, the generation and transmission cooperative (G&T) that owns the transmission circuit coming into the substation believes 4/0 equipment grounding is needed, while the consumer utilities operating the substation say 1/0 or 2/0 is required. We sometimes are required by the G&T to use double 4/0 to meet the required available fault current. Can you explain the disparity in requirements? Also, do we meet the OSHA requirements if we use the 1/0 or the 2/0 for equipment grounding...

Q: We have been reading OSHA 29 CFR 1910.269 regarding two-man work, but we cannot find a definition for “routine switching.” We are under the impression that a trained troubleshooter can replace blown fuses in cutouts without a second man. Since it is not specifically mentioned in the exceptions, do we have this wrong? We have old porcelain cutouts on our 4-kV system where you cannot remove the door with a stick and must grab it with your hand, putting the worker within the minimum approach distance of the energized 15-kV overbuild above. This is especially an issue for us at night and in storms....

Q: We have received some pushback from clients when setting up transmission pulling on EPZ mats that are constructed over crane mats, covered with galvanized cattle panels, overlapped, stapled down and bonded together. We follow a model passed down through our parent company’s safety research committee. Our clients have asked if the installation is certified. We did some research, found ASTM F2715 and are now wondering if that is what we should be doing. Can you help?

Q: Why do some experts say ground rods won’t work to trip a circuit? A: The experts say this because they are right depending on the conditions, which we’ll soon discuss. But let’s start with a definition of the idea of “remote ground” as the point at which we connect a protective system to earth. The lower the resistance of that remote ground connection to earth, the more current flows and the faster a fault clears. So, what we should be doing as a rule is using the best available ground to remote earth. The problem is that we often overlook a key element in this debate, which is that the ground...

Q: We don’t provide self-rescue equipment for lone workers, but we recently heard that OSHA is requiring self-rescue equipment as part of the General Duty Clause. Are you familiar with this? A: This is a complex question, part of which might border on legal arguments. Incident Prevention relates legal opinions to our readers from case outcomes that we are familiar with, but in practice avoids rendering advice or opinions that may border on legal terms. The rescue requirements in the OSHA rules do not address self-rescue. Many employers address self-rescue in part based on their interpretation...