P&P C-41B

Issue Date: 5/15/94
Revised: 8/1/94
AUTHORITY: California Labor Code §§6500 through 6510 and Title 8 California Code of Regulations §§341, 8470 and 7068 through 7071.

POLICY: It is the policy of the Division of Occupational Safety and Health to ensure through its permit procedures that specified hazardous activities proceed safely. The issuance of a permit by the Mining and Tunneling Unit for the use of diesel-powered engines or equipment underground provides the Division with an opportunity to determine that employers are aware before they commence work involving the use of diesel engines underground that they must comply with all applicable Title 8 Safety Orders, including any special requirements which the Mining and Tunneling Unit deems necessary, and to identify the location of hazardous activities which are most likely to pose a risk of employee injury or illness.



Whenever an employer plans to use a diesel engine in any underground worksite, a Permit to Use Diesel Engines Underground (Diesel Engine Permit) shall be obtained by the employer from the Mining and Tunneling Unit (M&T Unit).

NOTE: No fuel burning or internal combustion engine, other than diesel engines, are permitted to operate in any underground worksite, i.e., mines, tunnels or other similar subterranean workplace.


  1. Annual Permit

    The Division of Occupational Safety and Health does not issue Annual Permits for the use of diesel engines underground.

  2. Diesel Engine Permit

    1. Application Requirements

      1. A Permit for the use of diesel engines underground shall be obtained prior to commencement of any activity involving the use of diesel engines underground by each employer directly involved in the operation of the diesel engine.

      2. A Permit Applicant who plans to operate a diesel engine underground shall complete a Diesel Permit Application, M&T Form DPA (see Attachment A) and submit a Permit Application Fee of $50.00.

      3. A Permit Applicant working at a multi- employer worksite shall submit with the Diesel Permit Application a written statement or letter from the entity who controls the main ventilation system for the underground worksite that the worksite will receive at least the minimum amount of fresh air required for safe operation of the diesel equipment.

      4. The Permit Application shall also be supplemented by the following items:

        1. Specifications for the diesel engine and exhaust conditioning devices;

        2. Type of underground classification;

        3. An underground map;

        4. Detailed ventilation plans and ventilation calculations;

        5. Injury and Illness Prevention (IIP) Program;

        6. Code of Safe Practices;

        7. Emergency Plan and Safety Instructions for Employees;

        8. List of General Safety Precautions and availability of emergency medical services, including personnel certified in first aid; and

        9. A written plan for gas testing, ventilation controls and measurements, and exhaust conditioner inspection and records.

    2. Issuance

      1. A Diesel Engine Permit (M&T Form DEP) shall be issued listing each diesel engine operating at a single, contiguous worksite. Each separately ventilated underground work area shall have a separate listing on the Permit if the ventilation substantially differs between areas.

        NOTE: If page one of the Diesel Engineer Permit does not contain enough space for all of the listings, enter additional listings on additional pages of the Permit (see Attachment B).

      2. A Diesel Engine Permit shall be issued by the Senior Safety Engineer of the M&T Unit Office responsible for the geographical area in which the equipment is to be used, or his or her designee.

      3. Any special conditions for the Permit shall be specified on the Diesel Engine Permit. These conditions can include the following, when applicable:

        1. Only equipment approved by the Mine Safety and Health Administration (MSHA) or equipment accepted by the Division and maintained in good condition shall be allowed in underground areas classified as gassy; and

        2. Ventilation systems and diesel equipment exhaust conditioning systems shall not be modified after permit issuance, unless modified in accordance with the amendment procedures found in Section E. of this P&P.

      3. Temporary Permit

      The Division of Occupational Safety and Health does not issue temporary permits to Use Diesel Engines Underground.


The fee for a Diesel Engine Permit shall be $50.00 per Diesel Engine Permit.

NOTE: No additional fees shall be assessed by the Division for the amendments and the writing and sending of any letters required by P&P C-41B.


  1. The M&T Unit Senior Safety Engineer, or his or her designee, shall hold a Safety Permit Conference with the Permit Applicant prior to issuing an Diesel Engine Permit and shall summarize the results of the Safety Permit Conference in the Permit File using Attachments F and G of P&P C-41, or the equivalent.

    NOTE: When the Permit Applicant has demonstrated to the M&T Unit through recent experience with a previous Diesel Engine Permit that an in-person Safety Permit Conference is not necessary, the M&T Unit Senior Safety Engineer, or his or her designee, may hold a telephonic Safety Permit Conference with the Permit Applicant and document key elements in the file.

  2. The Safety Permit Conference shall be attended by the Permit Applicant who shall be knowledgeable about, and in a position of authority and responsibility with respect to, the permitted activity. The Safety Permit Conference may also include any other parties involved with the operation whose presence is necessary for a proper evaluation of the hazards associated with the use of diesel engines underground, e.g., the representatives of the owner or the contracting agency, the general contractor, any employer whose employees may be exposed to the hazards, and employees or their representatives.

  3. At the Safety Permit Conference, the potential risks of the operation shall be discussed and the employer shall identify the specific measures that will be taken to minimize these risks to employees.

  4. During the Permit Safety Conference, the applicant must provide enough detail to allow a reasonable determination to be made that the project will proceed in a safe manner. Therefore, the applicant shall be prepared to provide to the M&T Unit all components of the Permit Application, including supplemental materials as referenced in Section B.2.a.(4).i. through ix.

  5. The Permit Applicant shall discuss any unique risks of the jobsite affecting safety and health and provide evidence that the Applicant's IIP Program addresses these features.

  6. Details of the project shall be reviewed along with the most important safety and health issues and Safety Orders applicable to the type of work the Permit Applicant is going to perform.

  7. At multi-employer worksites, a single Safety Permit Conference may be held by the M&T Unit Senior Safety Engineer with all Applicants who are seeking a Diesel Engine Permit, if appropriate.

  8. At the Safety Permit Conference, the Permit Applicant shall be informed that the permitted activity is subject to inspection by the Division at any time during the performance of the permitted activity.


  1. The Permit Holder shall notify the M&T Unit Office which issued the Diesel Engine Permit of any significant change in the conditions referred to on the Diesel Engine Permit Application Form or any change in the representations made at the Permit Safety Conference.

  2. When the M&T Unit Office is notified of changes in the information provided at the time of permit application was first completed, it may determine that a safety conference or other action is necessary to determine the impact of the change on the safety of the job.


If the M&T Unit decides that a Permit Applicant is to be denied a Diesel Engine Permit, or a Permit Holder is to have his or her Permit suspended or revoked as provided by 8 CCR §8470(d) or 7070(e), the Denial, Revocation or Suspension Procedures found in P&P C-41A, pp. 18-23, shall be followed.


If a contractor has been denied a Diesel Engine Permit, or the contractor's Permit has been revoked or suspended, or the contractor has been cited by the Division for failure to obtain a Permit, and the contractor continues to engage in work which requires a valid Diesel Engine Permit, a request for a restraining order shall be made by the Senior Safety Engineer, through the Principal Engineer, to the Legal Unit (See 6510).


An inspection shall be scheduled for all Diesel Engine Permits which were issued after a telephonically conducted Safety Permit Conference, and all Permits involving equipment which was not evaluated during the Safety Permit Conference.


  1. Diesel Engine Permits shall be logged in the Diesel Permit Log (see Attachment C) and be identified by being sequentially numbered starting with 001 at the beginning of each fiscal year. The number shall constitute the first three digits of the log number, followed by the IMIS assigned engineer's area code for the county where the project is located. The third series of numbers shall indicate the fiscal year in which the permit is issued, followed by an "M" or "T" to indicate a mine or tunnel. The various Permit Codes used for completing the logging process are listed in Attachment D.

    EXAMPLE: The second Diesel Engine Permit issued for a tunnel in area 2 for fiscal year 1994 would be assigned log number 002-02-94-T. If at a later date, this permit is amended three times, the third amendment would be assigned log number 002- 02-94-T-(3).

  2. Once the Permit Fee is collected from the Permit Applicant, the Permit shall be issued to the Applicant. All checks and money orders shall be made payable to the State of California. If cash is received, send a money order or personal check for the amount of the Permit Fee, made payable to the State of California, to Accounting. Attach a copy of the Diesel Permit to the check.

  3. After the Senior Safety Engineer, of his or her designee, prepares a draft of the Diesel Engine Permit, the M&T Unit Office Support Staff shall type a final version of the Diesel Engine Permit on a new Form B and enter the log number on the permit. After typing the final version of the Diesel Engineer Permit, the Permit shall be given, along with any other relevant information, to the Senior Safety Engineer for review, signature and date.

  4. A letter of transmittal shall be prepared and signed by the Senior Safety Engineer and sent with the Diesel Permit to the Applicant.

  5. After the Permit and letter are signed, make four copies of each to be distributed as follows:

    1. Original to the Permit Applicant.

    2. Copy to the M&T Unit Principal Engineer.

    3. Copy to the field safety engineer.

    4. Copy for the employer's case file (together with any other relevant information including a copy of the check).

    5. Copy for Diesel Engine Permit file for current fiscal year.

  6. A copy of the Diesel Permit Log shall be sent to the Permit Unit at Division Headquarters at the end of each month. If no Permits are issued in a particular month, note the same on the Log and forward a copy to the Division's Permit Unit Office.

Attachments: A -- Cal/OSHA 41B-DPA -- Cal/OSHA 41B-DEP Page 1 Cal/OSHA 41B-DEP Page 2 C -- Diesel Permit Log [EXAMPLE NOT AVAILABLE] D -- Permit Codes [EXAMPLE NOT AVAILABLE] E -- List of DOSH District Offices