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• Standard Number: 1910.106(b)(4)(iv)(e)

March 18, 1976

Mr. F. P. Clayton
Assistant Superintendent
Loss Control and Engineering Department
Continental Insurance Companies
10 Park Place
Newark, New Jersey 07101

Attention: Mr. Charles Troell

Dear Mr. Clayton:

This is in response to your letter to our New York Regional Office dated December 18, 1975. This correspondence concerning lathes, explosion proof motors and storage tank fill pipes was forwarded to this office for reply. This also confirms the telephone conversation between Mr. Charles Troell and a member of my staff on February 27, 1976.

In reference to your question concerning Point of Operation Guarding for lathes, as you realize, the point of operation on this type of machine is not the major hazard. Most injuries are likely to occur from contact with exposed projections, flying metal chips, hot oil, rotating parts or stock, etc. When splash shields or chip shields are so designed and used to prevent the operator from having any part of his body in the danger zone during the operating cycle, they may be considered as a point of operation guard on this type of machinery.

National Electric Code (NEC) 501-5(a)(1), Sealing and Drainage, provides that "Seals in conduit runs entering an enclosure shall be placed as close as practicable and in no case more than 18 inches from enclosures." This would permit a seal on an explosion proof motor junction box if the seal meets the specifications of NEC 501-5(c) for the compound and there are no other junction boxes intervening.

29 CFR 1910.106(b)(4)(iv)(e), Fill Pipes In Tanks, specifically requires that the fill-pipe terminate no more than 6 inches from the bottom of the tank. Diverting the pipe against the side of the vessel at any distance from the bottom in excess of 6 inches would be a violation of this standard. In the case of glass-lined vessels; if the outer material of the vessel is electrically conductive, then the usual bonding or grounding requirements would apply, in order to obviate any difference in potentials between transfer lines and the vessel.

Hopefully this information will be helpful to you. If I can be of any further assistance, please feel free to contact me.

Sincerely,



Barry J. White
Associate Assistant Secretary
for Regional Programs


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