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Electrical Hazards
Suspended scaffolds are often made of metal and sometimes used in close proximity to overhead power lines. These factors introduce the risk of electrocution. However, proper clearance and maintenance reduce this risk. Note: Except where indicated, these requirements also apply to multi-level, single-point adjustable, multi-point adjustable, interior hung, needle beam, catenary, and float (ship) scaffolds.
Overhead Power Lines
  • Scaffolds must be far enough from overhead power lines that neither they, nor any conductive materials (e.g. building materials, paint roller extensions, scaffold components) that may be handled on them, come closer than 10 feet to the power line (Figure 1). [1926.451(f)(6)]

    • Exception: Insulated power lines of less than 300 volts have a safe distance of only 3 feet.

TIP: Because it may be difficult to determine if a power line is insulated, or what its exact voltage is, the 10 ft. rule should always be applied.

  • Scaffolds may be closer to overhead power lines than specified above if such proximity is necessary for the type of work being done, and if the power company or electrical system operator has been notified and has either:

    • De-energized the lines;

    • Relocated the lines; or

    • Installed protective coverings to prevent accidental contact with the lines. [1926.451(f)(6)]
Figure 1. Not only is this job-made scaffold in violation of standards pertaining to capacity and fall protection, but the metal platform is in contact with a live powerline.

Figure 1.
Not only is this job-made scaffold in violation of standards pertaining to capacity and fall protection, but the metal platform is in contact with a live power line.




Welding
  • When welding is being performed from suspended scaffolds, the following precautions must be taken, as they apply, to reduce the possibility of welding current arcing through the suspension wire ropes: [1926.451(f)(17)]

    • An insulated thimble must be used to attach each suspension wire rope to its hanging support (such as cornice hook or outrigger). Excess suspension wire rope and any additional independent lines from grounding must also be insulated; [1926.451(f)(17)(i)]

    • The suspension wire rope must be covered with insulating material at least 4 feet (1.2 m) above the hoist; [1926.451)(f)(17)(ii)]

    • If there is a tail line below the hoist, it must be insulated to prevent contact with the platform. The portion of the tail line that hangs free below the scaffold must be guided or retained, or both, so that it does not become grounded; [1926.451(f)(17)(ii)]

    • Each hoist must be covered with insulated protective covers; [1926.451(f)(17)(iii)]

    • In addition to a work lead attachment required by the welding process, a grounding conductor must connected from the scaffold to the structure (see Accident Report). The size of this conductor must be at least the size of the welding process work lead, and this conductor must not be in series with the welding process or the work piece; [1926.451(f)(17)(iv)]

    • An active welding rod or uninsulated welding lead must not be allowed to contact the scaffold or its suspension system; [1926.451(f)(17)(vi)]

    • If the scaffold grounding lead is disconnected at any time, the welding machine must be shut off. [1926.451(f)(17)(v)]

Subpart L Appendix E, Figure 2, contains an illustrated diagram of welding precautions for a suspended scaffold platform.

Figure 2. Suspended Scaffold Platform Welding Precautions.

Figure 2.
Suspended Scaffold Platform Welding Precautions.














View image.




Portable Electric Tools
  • Because metal frame scaffolds are conductive, power tools, cords, etc., that suffer insulation failure can electrify the entire scaffold. This poses a risk of electrocution not just to the worker holding the tool, but to everyone who contacts the scaffold. Therefore, all portable electric equipment must be protected by GFCIs (ground-fault circuit interrupters) or an AEGCP assured equipment grounding conductor program, in accordance with 1926.404(b)(1)(i) (see Electrical Incidents: Lack of Ground-Fault Protection in the OSHA Construction eTool).

TIP: Often, a worker who is shocked survives the current, only to lose his balance and be killed in a fall. This is one more reason for always using fall protection.

 
 
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