OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

January 13, 1998

Mr. D. K. Martin
Innsbrook Technical Center
5000 Dominion Boulevard
Glenn Allen, Virginia 23060

Dear Mr. Martin:

This is in response to your letter of December 2, 1996, addressed to Mr. Joseph Dear, former Assistant Secretary of the Occupational Safety and Health Administration (OSHA) in which you explained your concerns about a provision in the revised scaffold standard for construction, which was promulgated in August 1996. We appreciate your taking the time to write and follow up on the telephone with the Agency. We also apologize for the delay in responding to your letter.

Specifically, you asked for an interpretation of a provision, 29 CFR 1926.451(f)(17)(iv), that addresses arc welding from a suspended scaffold and which requires that a grounding lead be connected from the scaffold to the structure. You listed several potential hazards that exist inside coal- or oil-fired boilers, and you were concerned that the added weight to the scaffoldrom the ground lead might compromise the manufacturer's safe working load or create an off-center distribution of weight. We believe the problem of eccentric loading can be solved by rigging the lead so that it hangs down from the center of the platform. We also note that the weight calculations are based on the entire length of lead being suspended from the scaffold, and this is not likely to occur. However, in those situations where the grounding lead could cause overloading, then it would be necessary to reconfigure the load on the scaffold, use a different scaffold, or develop an alternative method of providing electrical protection.

Under the circumstances you have described, to ensure that workers are protected from electrical hazards when they are arc welding from a suspended scaffold, you could have an engineer develop an alternative grounding procedure and determine if the insulated thimble(s), hoist(s), and wire rope will prevent the flow of uncontrolled current through the suspension rigging and platform. You could also do a hazard assessment to develop procedures for the testing, placement, and determination of appropriate insulation that a qualified person would follow to protect the workers on the scaffold.

OSHA plans to open rulemaking again for the construction scaffold next year. At that time, we will review the concerns raised in your letter again, and any additional comments concerning protective measures and insulation for scaffolds in metal tanks would be welcome at that point. The Federal Register document to reopen the rulemaking will also be available at OSHA's home page (
http://www.osha.gov). In addition, copies of the document will be obtainable from OSHA's Publications Office (telephone (202) [693-1888].) Should you require further assistance, please do not hesitate to [contact us by fax (202-693-1689) at: U.S. Department of Labor — OSHA, Directorate of Construction, Office of Construction Standards and Guidance. You can also contact us by mail at the above office, Room N3468, 200 Constitution Avenue, N.W., Washington, DC 20210; although, there will be a delay in our receiving correspondence by mail.]


Russell B. Swanson, Director
Directorate of Construction

Corrected on 04/10/2006

Monday, December 02, 1996
Joseph Dear, Assistant Secretary of Labor
U.S. Department of Labor
Occupational Safety & Health Administration

Dear Mr. Dear:

Introduction: We are concerned about a section of the newly promulgated scaffold standard which appeared in Federal Register/Vol. 61, #170.

Request: I would like to request your formal interpretation of 29 C.F.R. 1926.451(f)(1)(7)[iv].

Background: Virginia Power Fossil & Hydro does extensive interior boiler repair. The work scopes involve arc welding from a single point suspended scaffold. We totally isolate the scaffold [electrically] using insulative materials.

Hazard Assessment: The interior of a coal or oilfired boiler is not suitable for an electrical ground, therefore the required ground lead would have to be routed to the proximity of the welding machine ground. I think this added lead would add the following hazards:


  • catching rough boiler interiors causing the single point suspended scaffold to tip.
  • adding weight to a scaffold system that is close to the recommended allowance.
  • adding an "off center" weight burden, causing a less than level accent/decent.

One Example: The manufacturer's recommended safe working load may be compromised! An example...one single point suspended scaffold [load rating 700 lbs.] The load that could be induced on this scaffold considering the new ground. lead reg...



two welders @ 220 lbs. ea. = 440 lbs.
tools & welding supplies = 40 lbs.
stinger lead @ 1 lb./ft. = 150 lbs.
ground lead @ 1 lb./ft. = 150 lbs.
total = 780 lbs.

total represents an 11% overload

Conclusion: I think the ground lead requirement transforms a safe work process into a more hazardous one. This requirement should be removed from the standard.


D. K. Martin

note: ground reads of #2.0 copper = 1 lb./ 1 ft.