
[Code of Federal Regulations]
[Title 30, Volume 1]
[Revised as of July 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 30CFR7]

[Page 19-22]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 7--TESTING BY APPLICANT OR THIRD PARTY--Table of Contents
 
Subpart C--Battery Assemblies

Sec. 7.41  Purpose and effective date.

    This subpart establishes the specific requirements for MSHA approval 
of battery assemblies intended for incorporation in approved equipment 
in underground mines. It is effective August 22, 1988. Applications for 
approval or extensions of approval submitted after August 22, 1989, 
shall meet the requirements of this part.

Sec. 7.42  Definitions.

    The following definitions apply in this subpart:
    Battery assembly. A unit or units consisting of cells and their 
electrical connections, assembled in a battery box or boxes with covers.
    Battery box. The exterior sides, bottom, and connector receptacle 
compartment, if any, of a battery assembly, excluding internal 
partitions.

Sec. 7.43  Application requirements.

    (a) An application for approval of a battery assembly shall contain 
sufficient information to document compliance with the technical 
requirements of this subpart and include a composite drawing with the 
following information:
    (1) Overall dimensions of the battery assembly, including the 
minimum distance from the underside of the cover to the top of the 
terminals and caps.
    (2) Composition and thicknesses of the battery box and cover.
    (3) Provision for securing covers.
    (4) Documentation of flame-resistance of insulating materials and 
cables.
    (5) Number, type, and rating of the battery cells.
    (6) Diagram of battery connections between cells and between battery 
boxes, except when connections between battery boxes are a part of the 
machine's electrical system.
    (7) Total weight of the battery, charged and ready for service.
    (8) Documentation of materials and configurations for battery cells, 
intercell connectors, filler caps, and battery top:
    (i) If nonmetallic cover designs are used with cover support blocks; 
or
    (ii) If the cover comes into contact with any portion of the cells, 
caps, filler material, battery top, or intercell connectors during the 
impact test specified by Sec. 7.46.
    (b) All drawings shall be titled, dated, numbered, and include the 
latest revision number.

[53 FR 23500, June 22, 1988, as amended at 60 FR 33723, June 29, 1995]

[[Page 20]]

Sec. 7.44  Technical requirements.

    (a)(1) Battery boxes and covers constructed of AISI 1010 hot rolled 
steel shall have the following minimum thicknesses based on the total 
weight of a unit of the battery assembly charged and ready for service:

------------------------------------------------------------------------
          Weight of battery unit             Minimum required thickness
------------------------------------------------------------------------
1,000 lbs. maximum........................  10 gauge or \1/8\" nominal
1,001 to 2,000 lbs........................  7 gauge or \3/16\" nominal
2,001 to 4,500 lbs........................  3 gauge or \1/4\" nominal
Over 4,500 lbs............................  0 gauge or \5/16\" nominal
------------------------------------------------------------------------

    (2) Battery boxes not constructed of AISI 1010 hot rolled steel 
shall have at least the tensile strength and impact resistance of 
battery boxes for the same weight class, as listed in paragraph (a)(1) 
of this section.
    (3) Battery box covers constructed of materials with less than the 
tensile strength and impact resistance of AISI 1010 hot rolled steel or 
constructed of nonmetallic materials shall meet the acceptable 
performance criteria for the impact test in Sec. 7.46. Nonmetallic 
covers shall be used only in the battery assembly configuration in which 
they pass the impact test.
    (4) Nonmetallic materials for boxes and covers shall--
    (i) Be accepted by MSHA as flame-resistant material under part 18 of 
this chapter; and
    (ii) Meet the acceptable performance criteria for the deflection 
temperature test in Sec. 7.47.
    (b) All insulating material shall have a minimum resistance of 100 
megohms at 500 volts d.c. and be accepted by MSHA as flame resistant 
under part 18 of this chapter.
    (c) Battery box and cover insulating material shall meet the 
acceptable performance criteria for the acid resistance test in 
Sec. 7.48.
    (d) Covers shall be lined with insulating material permanently 
attached to the underside of the cover, unless the cover is constructed 
of insulating material.
    (e) Covers, including those used over connector receptacle housings, 
shall be provided with a means of securing them in a closed position.
    (f) Battery boxes shall be provided with vent openings to prevent 
the accumulation of flammable or toxic gases or vapors within the 
battery assembly. The size and location of openings shall prevent direct 
access to cell terminals and other uninsulated current carrying parts. 
The total minimum unobstructed cross-sectional area of the ventilation 
openings shall be no less than the value determined by the following 
formula:
[GRAPHIC] [TIFF OMITTED] TC15NO91.011

N = Number of cells in battery box.
R = Rated 6 hour battery capacity in ampere hours.
M = Total minimum ventilation area in square inches per battery box.

    (g) Battery boxes shall have drainage holes to prevent accumulation 
of water or electrolyte.
    (h) Battery cells shall be insulated from the battery box walls, 
partitions and bottom by insulating material, unless such part of the 
battery box is constructed of insulating material. Battery box wall 
insulating material shall extend to the top of the wall.
    (i) Cell terminals shall be burned on, except that bolted connectors 
using two or more bolts may be used on end terminals.
    (j) Battery connections shall be designed so that total battery 
potential is not available between adjacent cells.
    (k) Cables within a battery box shall be accepted by MSHA as flame 
resistant under part 18 of this chapter or approved under subpart K of 
this part. The cables shall be protected against abrasion by insulation, 
location, clamping, or other effective means.
    (l) When the battery plug and receptacle are not located on or 
within the battery box, strain on the battery terminals shall be 
prevented by a strain-relief device on the cable. Insulating material 
shall be placed between the strain-relief device and cable, unless the 
device is constructed of insulating material.
    (m) At least a \1/2\-inch air space shall be provided between the 
underside of the battery cover and the top of the battery, including the 
terminals and connectors.

[53 FR 23500, June 22, 1988, as amended at 57 FR 61220, Dec. 23, 1992]

[[Page 21]]

Sec. 7.45  Critical characteristics

    The following critical characteristics shall be inspected or tested 
on each battery assembly to which an approval marking is affixed:
    (a) Thickness of covers and boxes.
    (b) Application and resistance of insulating material.
    (c) Size and location of ventilation openings.
    (d) Method of cell terminations.
    (e) Strain relief devices for cables leaving boxes.
    (f) Type, location, and physical protection of cables.

Sec. 7.46  Impact test.

    (a) Test procedures. (1) Prepare four covers for testing by 
conditioning two covers at -13  deg.F (-25  deg.C) and two covers at 122 
 deg.F (50  deg.C) for a period of 48 hours.
    (2) Mount the covers on a battery box of the same design with which 
the covers are to be approved, including any support blocks, with the 
battery cells completely assembled. If used, support blocks must contact 
only the filler material or partitions between the individual cells. At 
the test temperature range of 65  deg.F -80  deg.F (18.3  deg.C-26.7 
deg.C), apply a dynamic force of 200 ft. lbs. to the following areas 
using a hemispherical weight with a 6" maximum radius:
    (i) The center of the two largest unsupported areas;
    (ii) The areas above at least two support blocks, if used;
    (iii) The areas above at least two intercell connectors, one cell, 
and one filler cap; and
    (iv) Areas on at least two corners. If the design consists of both 
inside and outside corners, test one of each.
    (3) Record the condition of the covers, supports, intercell 
connectors, filler caps, cell covers, and filler material.
    (b) Acceptable performance. Impact tests of any of the four covers 
shall not result in any of the following:
    (1) Bent intercell connectors.
    (2) Cracked or broken filler caps, except plastic tabs which extend 
from the body of the filler caps.
    (3) Cracks in the cell cover, cells, or filler material.
    (4) Cracked or bent supports.
    (5) Cracked or splintered battery covers.

[53 FR 23500, June 22, 1988, as amended at 60 FR 33723, June 29, 1995]

Sec. 7.47  Deflection temperature test.

    (a) Test procedures. (1) Prepare two samples for testing that 
measure 5 inches by \1/2\ inch, by the thickness of the material as it 
will be used. Prior to testing, condition the samples at 
73.4<plus-minus> 3.6  deg.F (23<plus-minus>2  deg.C) and 
50<plus-minus>5% relative humidity for at least 40 hours.
    (2) Place a sample on supports which are 4 inches apart and immersed 
in a heat transfer medium at a test temperature range of 65  deg.F-80 
deg.F (18.3  deg.C-26.7  deg.C). The heat transfer medium must be a 
liquid which will not chemically affect the sample. The testing 
apparatus must be constructed so that expansion of any components during 
heating of the medium does not result in deflection of the sample.
    (3) Place a temperature measuring device with an accuracy of 1% into 
the heat transfer medium within \1/8\ inch of, but not touching, the 
sample.
    (4) Apply a total load, in pounds, numerically equivalent to 11 
times the thickness of the sample, in inches, to the sample midway 
between the supports using a \1/8\ inch radius, rounded contact. The 
total load includes that weight used to apply the load and any force 
exerted by the deflection measurement device.
    (5) Use a deflection measuring device with an accuracy of 
<plus-minus>.001 inches to measure the deflection of the sample at the 
point of loading as the temperature of the medium is increased at a 
uniform rate of 3.6<plus-minus>.36  deg.F/min. (2<plus-minus>0.2  deg.C/
min.). Apply the load to the sample for 5 minutes prior to heating, to 
allow compensation for creep in the sample due to the loading.
    (6) Record the deflection of the sample due to heating at 180  deg.F 
(82  deg.C).
    (7) Repeat steps 2 through 6 for the other sample.
    (b) Acceptable performance. Neither sample shall have a deflection 
greater than .010 inch at 180  deg.F (82  deg.C).

[53 FR 23500, June 22, 1988; 53 FR 25569, July 7, 1988; 60 FR 33723, 
June 29, 1995]

[[Page 22]]

Sec. 7.48  Acid resistance test.

    (a) Test procedures. (1) Prepare one sample each of the insulated 
surfaces of the battery box and of the cover that measure at least 4 
inches by 8 inches, by the thickness of the sample which includes the 
insulation plus the battery cover or box material. The insulation 
thickness shall be representative of that used on the battery box and 
cover. If the insulation material and thickness of material are 
identical for the battery box and cover, only one sample need be 
prepared and tested.
    (2) Prepare a 30 percent solution of sulfuric acid (H<INF>2</INF> 
SO<INF>4</INF>) by mixing 853 ml of water with 199 ml of sulfuric acid 
(H<INF>2</INF> SO<INF>4</INF>) with a specific gravity of 1.84. 
Completely cover the samples with the acid solution at the test 
temperature range of 65  deg.F-80  deg.F (18.3  deg.C-26.7  deg.C) and 
maintain these conditions for 7 days.
    (3) After 7 days, record the condition of the samples.
    (b) Acceptable performance. At the end of the test, the insulation 
shall not exhibit any blistering, discoloration, cracking, swelling, 
tackiness, rubberiness, or loss of bond.

[53 FR 23500, June 22, 1988, as amended at 60 FR 33723, June 29, 1995]

Sec. 7.49  Approval marking.

    Each approved battery assembly shall be identified by a legible and 
permanent approval plate inscribed with the assigned MSHA approval 
number and securely attached to the battery box.

Sec. 7.50  Post-approval product audit.

    Upon request by MSHA, but no more than once a year except for cause, 
the approval-holder shall make an approved battery assembly available 
for audit at no cost to MSHA.

Sec. 7.51  Approval checklist.

    Each battery assembly bearing an MSHA approval plate shall be 
accompanied by a description of what is necessary to maintain the 
battery assembly as approved.

[53 FR 23500, June 22, 1988, as amended at 60 FR 33723, June 29, 1995]

Sec. 7.52  New technology.

    MSHA may approve a battery assembly that incorporates technology for 
which the requirements of this subpart are not applicable, if the Agency 
determines that the battery assembly is as safe as those which meet the 
requirements of this subpart.
