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Grounding or double insulation for battery chargers

Summary An attorney asked whether a battery charger for rechargeable tools always needed grounding or double insulation. OSHA identified conditions that triggered one of those protections, including hazardous locations, higher voltage and damp or conductive work areas. It also said approved equipment must be used under its testing laboratory's conditions.
Document
Federal opinion letter
Agency
Occupational Safety and Health Administration (OSHA)
Document number
1996-03-12-0
Date issued
March 12, 1996
Status
Active
Status last verified October 9, 2026
Topics
Workplace Safety OSHA 1910 Electrical Safety Battery Chargers
Source
View the official document

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About this page: The full text below is the official document from Occupational Safety and Health Administration (OSHA). Ezel adds the plain-English summary and tracks the document's status. The official source linked on this page is authoritative for any reliance.

March 12, 1996

Mr. Barron L. Stroud, Jr.
Law Offices of Miles
& Stockbridge
[Recipient address omitted]
Dear Mr. Stroud:

This is in response to your April 18 letter requesting clarification regarding the grounding requirements of 29 CFR 1910.304 with respect to a battery charger used with rechargeable power tools. Please accept our apology for the delay in responding. Your question and our reply follow.

Question: Is an approved battery charger required to be either grounded or double-insulated under the requirement of 29 CFR 1910.304?

Reply: Paragraph 1910.304(f)(5)(v) contains requirements for grounding cord- and plug-connected equipment. According to this rule, a cord- and plug-connected battery charger must be grounded or double-insulated:

  1. If it is used in a hazardous location, defined under paragraph 1910.307.

  2. If it operates at more than 150 volts, or

  3. If it is used in damp or wet locations or by employees standing on the ground or on metal floors or working inside of metal tanks or boilers.

If a system of double insulation is used, the portable battery charger must be distinctively marked to indicate that it utilizes an approved system of double insulation. (See the paragraph following 29 CFR 1910.304(f)(5)(v)(c)(8)).

Please note under paragraph 1910.399 that "approved" is defined as "acceptable" which is defined as "accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a nationally recognized testing laboratory" (NRTL). An employer must follow the conditions of use assigned to approved equipment or installations by the NRTL to be in compliance with Occupational Safety and Health Administration regulations. A listing of NRTL's is enclosed for your use.

If we may be of further assistance, please contact the Office of General Industry Compliance Assistance, M. Ronald Davies, telephone (202)219-8031, extension 110.

Sincerely,
John B. Miles, Jr., Director
Directorate of Compliance Programs

Enclosure

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

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