Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

February 16, 1977

Mr. Charles J. Troell
Senior Field Representative
Loss Control & Engineering
Department The Continental Insurance
Companies Ten Park Place
Newark, New Jersey 07101

Dear Mr. Troell:

This is in response to your letter requesting further information on the ground-fault circuit interrupter protection devices and their application.

Somewhat more than a year ago, there was an OSHA requirement for the Construction Industry to provide GFCI in construction operations. This Standard was withdrawn during the year of 1975, and as of December 21, 1976 has been reinstated effective 60 days from that date of the publication of the Federal Register. We are enclosing a copy of the Federal Register article on that particular item. This new regulation on GFCI requires either that a ground fault circuit interrupter system be installed in accordance with the NEC Standard or that a program of ground fault testing be initiated in such manner that any change to outlets, circuits or systems would require testing for grounds or a test shall be made not less than once every three months in the absence of any changes in the system. It should be clearly understood that the requirements for GFCI do not apply to circumstances other than those specified in the National Electrical Code.

In your second paragraph, you ask information about "emergency venting" when applied to stills and reactors. Under 1910.106(b)(2)(v)(e), on page 128 of the January 1976 issue of the Federal Register, you will find a formula for determining emergency relief venting for all types of flammable liquids. The three questions based upon the preceding paragraph would elicite the following responses:

1. Discharge to a safe location would mean that every consideration has been given to the potential ignition of flammable gases, the potential hazard to employees and the public from inhalation of toxic fumes, dusts, or gas generated by such emission and finally, the requirements of the Environmental Protection Agency (EPA), in relation to air protection.

2. We have made a thorough search and have been unable to locate any mention of blow-down tanks or other controls of like type.

3. As to visual and audio warning systems, under 1910.106(h)(6)(iii), Alarm Systems, there is a specific requirement for the notification of fire to those within the plant and to any public fire department.

In your third paragraph, you request clarification of 1910.106(b)(3)(iv) which provides specific guides for the diameter and length of exhaust pipes. The Standard specifies that if the length of the pipe is under ten feet, and the diameter is greater than two inches ID, the outlet shall be provided with a vacuum or pressure relief device or a flame arrester. Alternately, the pipe must be at least 12 feet long and not less than 1-1/4 inches nominal inside diameter. The vent pipe is also related to the size and maximum flow GPM of the fill line in accordance to Table H 11 in 1910.106. One sentence in Paragraph IV, Vents, specifically states that vent pipes two inches or less in nominal inside diameter shall not be obstructed. Therefore, the proposed length and diameter in your third paragraph of your letter, do not meet the requirements of the Standard 1910.106.

We hope the preceding provides the information you require. Please feel free to contact us if there are further questions about OSHA.


Alfred Barden
Regional Administrator
Occupational Safety and Health Administration