Grounding lead for arc welding from a suspended scaffold

January 13, 1998
Mr. D. K. Martin
Innsbrook Technical Center
[Recipient address omitted]
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.]
Sincerely,
Russell B. Swanson, Director
Directorate of Construction
Corrected on 04/10/2006

[Requester letter reproduced on OSHA page; omitted here.]