Power line safe clearance
Hello, I would like some professional advice here. In the image, we have a scaffolding contractor who installed their scaffolding near overhead power lines. The image may not be clear, but the high tiering lines are over 10 feet from the scaffold and rated at 4,000kv. The lines midline/inferior to the pole do not have any nominal voltage rating. The lines midline to the pole appear to be fiber optics, but we are not sure. The scaffold face is 5 feet from the lines midline to the pole. The contractor current has no employees working near this section at the moment, and the scaffold construction was conducted without notice to me as I am the consultant for the construction firm. To the teammates here versed in NFPA standards or Cal OSHA, can we discuss this further?
I understand that an approaching boundary of live parts 50-600 nominal volts for unqualified electrical workers is 3.5 feet. Since the scaffold face is 5 feet from the supposed telecommunications cables midline to the pole, will this work be feasible? I do know here in California, 600v-50,000v allows for scaffolds to be as close as 6 feet from conducting lines.
(We are waiting to hear back from the utility operator to obtain actual voltage ratings for the section in this image)
Comments (7)
The federal OSHA minimum distance for overhead power lines is 10 feet of clearance for up to 50,000 volts, then an additional 4 inches for every 10 kV. The following is from NFPA 70E Annex N, which has the exact same clearance distances, but has additional requirements.
N.2 Overhead Power Line Policy (OPP).
This informative annex applies to all overhead conductors, regardless of voltage, and requires the following:
(1) That employees not place themselves in close proximity to overhead power lines. “Close proximity” is within a distance of 10 ft for systems up to 50 kV, and should be increased 4 in. for every 10 kV above 50 kV.
(2) That employees be informed of the hazards and precautions when working near overhead lines.
(3) That warning decals be posted on cranes and similar equipment regarding the minimum clearance of 10 ft.
(4) That a “spotter” be designated when equipment is working near overhead lines. This person’s responsibility is to observe safe working clearances around all overhead lines and to direct the operator accordingly.
(5) That warning cones be used as visible indicators of the 10 ft. safety zone when working near overhead power lines.
Informational Note: “Working near,” for the purpose of this informative annex, is defined as working within a distance from any overhead power line that is less than the combined height or length of the lifting device plus the associated load length and the required minimum clearance distance [as stated in N.2(1)]. Required clearance is expressed as follows:
Required clearance = lift equipment height or length + load length + at least 3 m (10 ft)
(6) That the local responsible person be notified at least 24 hours before any work begins to allow time to identify voltages and clearances or to place the line in an electrically safe work condition.
Kind of scary right? Scaffold builders moving all that conductive material around that high potential? And when do you ever hear of scaffold builders take electrical safety courses? Electrical safety is always taught like it's ELECTRICIAN safety when in fact, they can die just like I can, an electrician, from shock exposure. The most dangerous electrical hazard that kill 98-99% of workers exposed to electrical hazards.
Can you call the utility company and have them provide cover-up on the exposed lines near the work to be done to avoid accidental contact? Eliminate some risk. They would install insulating materials, like rubber and plastic (shown in image) to cover the lines.
Even though the scaffold is in excess of 10 foot from the high voltage lines, you have to remember that height differential will change (lessen) when persons occupy the scaffold. What conductive tools/equipment (if any) will the persons who are working on the scaffolding be using. Or if the tools/equipment is not conductive, but they are damp because of rain, humidity, etc., then non-conductive tools/equipment can still conduct electricity on the exterior of the non-conductive tools/equipment.
The photo appears to have wooden scaffold board, but if they were metal (aluminum, etc.,) or the boards were wet from recent rains, humidity, etc., then that is something that needs to be taken into consideration for work to take place on the scaffolding.
When you are dealing with overhead electrical lines. it is always better to be safe and not work near high voltage lines unless that is the only option available. Then if you have to do that, the utility company's involved should be required as a precaution to place high voltage shielding around the lines to protect the workers or better yet, have the electrical power turned off/re-routed from overhead. Remember Murphy is lurking out there to cause havoc if he can. Generally with electricity there are no do-overs.
You are doing the correct things on checking with the particular companies about the voltage. Never take anything for granted when it comes to dealing with potential high voltage overhead electrical lines. Better to be safe than to be sorry.