Question (1):
This question is posed with respect to hand power tools that are NOT designed for use in hazardous environments. Is it permissible to replace the plug of a double-insulated electric hand tool with after-market parts? Is it permissible to repair the (external) power cord?
Answer: It is permissible to replace the plug under certain conditions. OSHA's construction industry standards addressing grounding electric (power-operated) hand tools are in 29 CFR 1926.302(a). Section 1926.302(a)(1) states:
Electric power operated tools shall either be of the approved double-insulated type or grounded in accordance with Subpart K of this part [??1926.400-1926.449].
As you know, double-insulated tools have two-prong attachment plugs instead of a grounding (third) prong.
In addition, in 29 Part CFR 1926 Subpart K, ?1926.403(a) requires all electric equipment, including double-insulated tools, to be approved. "Approved" is defined in ?1926.449 as being "acceptable," which (for purposes of this question) is defined as "accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a qualified testing laboratory...." A double-insulated electric hand tool with its original two-prong attachment plug that has been listed by a nationally recognized testing laboratory (NRTL) would comply with ?1926.302(a).
(1)
With regard to the applicable provisions in the OSHA standards for inspecting these tools, ?1926.404(b)(1)(iii)(C) states:
(C) Each cord set, attachment cap, plug and receptacle of cord sets, and any equipment connected by cord and plug, except cord sets and receptacles which are fixed and not exposed to damage, shall be visually inspected before each day's use for external defects, such as deformed or missing pins or insulation damage, and for indications of possible internal damage. Equipment found damaged or defective shall not be used until repaired. [Emphasis added.]
You indicated that when these plugs are found to be damaged or the strain-relief is torn, you recommend that repairs be made, in accordance with ?1926.404(b)(1)(iii)(C). Enclosed with your letter was a commercially available polarized attachment plug, which you state is UL-rated and has an appropriate capacity for a double insulated tool with a 12- to 18-gauge cord. The plug is specifically designed for installation as a replacement plug.
To satisfy the requirements of the OSHA standards, a repair would have to restore the tool to its "approved" condition in accordance with ?1926.403(a). Tools, such as the double-insulated ones you address, are approved as complete factory-produced entities. The approval is for the tool as a whole -- its design, capacity, materials and construction. This provision precludes the use of an approved tool if its characteristics are materially altered. Also, it requires that the repair not compromise the integrity of the double-insulated construction.
Repair of double insulated tools
With respect to double insulated tools, competently made repairs to external parts of the tool, using parts that are at least equivalent to those used in the original tool, are permitted. For example, as long as the replacement plug is an approved item, has a capacity that meets or exceeds the original, and is properly installed, its use for repair is permitted.
Repairs that require opening the body of a double insulated tool are permitted under ?1926.403(a) if opening the tool body is consistent with the terms of the testing laboratory's approval of the tool as double-insulated. For example, if the terms of the testing laboratory's approval permits a competent repair technician or facility to open the body of the tool to replace the power cord on a double insulated drill, such a repair would be permitted under ?1926.403(a).
In addition, the cord may be repaired by severing the cord above bad area and installing an appropriate replacement plug as described above. However, repair of a cord for a tool such as a typical electric drill by splicing is not permitted. Section 1926.405(g)(2)(iii) states:
Flexible cords shall be used only in continuous lengths without splice or tap. Hard service flexible cords No. 12 or larger may be repaired if spliced so that the splice retains the insulation, outer sheath properties, and usage characteristics of the cord being spliced.
This provision precludes the repair of flexible cords smaller than No.12 (the higher the number, the smaller the cord). Since hand power tools typically have flexible power cords smaller than No.12, those cords are not permitted to be spliced. Heavier cords -- those No. 12 or larger (that is, with a lower gauge number), may be repaired with a molded or vulcanized splice as long as the repair returns the cord to at least the equivalent of its original specifications.
