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 5, 1984

                    AND AREA DIRECTORS

FROM:               JOHN B. MILES, JR., DIRECTOR 

SUBJECT:            Unapproved Plug and Socket Combination

In accordance with OSHA Instruction CPL 1.1, Special Violations Alert System, this safety alert is being issued pursuant to a request from the New York Regional Office to alert other Regions of a flaw in the insulation of a TRW "Jones" plug/socket combination which resulted in an electrocution.

TRW "Jones" plugs and sockets come in four series, Nos. 300, 400, 2400 and 500 (rated for 730 Volts, 1100 Volts, 1700 Volts and 3000 Volts rms, respectively). The 400 and 500 series have a metal, non-current carrying external hood with which a person can readily make contact. Beneath the metal hood there is an insulation liner to prevent direct contact between current carrying wires and metal hood. The flaw noted on the 400 series plug during the inspection was that the insulation liner was not sufficiently large and a region of the metal hood could be touched by a current carrying wire, thus allowing for electrical shock to a person who might touch the metal hood. A more detailed description of the "Jones" plug/socket combination, a diagram of the insulation flaw, and other relevant TRW literature are enclosed. In a telephone conversation, TRW affirmed that the 400 and 500 series plug/socket combinations are not UL recognized, in violation of 29 CFR 1910.303(a). (The manufacturer's literature does not claim that the 400 and 500 series plug/socket combinations are UL-recognized.)

In the situation investigated in Region II, it appeared that the direct cause of death was the energizing of the metal hood of the 400 series plug by a loose strand of wire.

As can be seen from TRW's literature, the 300 and 2400 series plug/socket combination are UL-recognized. These two types of plugs and sockets have effective means of preventing accidental contact with live parts, and their proper use does not constitute a violation of the electrical standards.

All OSHA field offices should be aware of this hazard and should take appropriate action, as required, to ensure compliance with the appropriate standard for safe electrical equipment.