Current through Register Vol. 43, No. 02, November 27, 2024
(1)
Inspection
Reports - At each mine where electricity is used underground, a
systematic inspection of all wiring and equipment shall be made at regular
intervals, at least once every month. A written or verbal report of each
inspection shall be made by the mine electrician or inspector to the mine
foreman. Equipment and circuits found to be defective shall be immediately
removed from service until repaired.
(2)
Marking
Switches_- All electrical control switches shall be plainly
marked, with the name of the machine which each controls.
(3)
Insulated
Platforms - At any place in the mine where it is necessary to
manipulate or adjust "live" equipment operating at more than three hundred
(300) volts, including switches, motor starters, or other controlling
appliances, insulated platforms shall be provided and used.
(4)
Installation and Grounding
Electrical Equipment - The frames and bed plates of generators,
transformers, compensators, rheostats, motors and switches shall be effectively
grounded. All metallic covering and conduit shall also be grounded. Such
grounded shall be to water pipe systems, bonded rail or artificial ground, with
preference in the order named. Where trailing cables are used, it is
recommended that such cables contain a separate wire to be used as a ground
wire.
(a) The ground connection to metallic
piping systems shall be made by means of an approved clamp firmly belted to the
pipe after all rust and scale have been removed, or by means of a brass plug
which has been tightly screwed into a pipe fitting or where the pipe is of
sufficient thickness, screwed into a hole in the pipe itself, or by other
equivalent means. The grounding conductor shall be attached to the clamp or to
the plug by means of solder or by an approved solderless connector.
(b) If conduit, couplings, or fittings having
protective coating of non-conducting material, such as enamel, are used, such
coating shall be thoroughly removed from couplings, conduits and such surfaces
of fittings where the conduit or ground clamp is secured, in order to obtain a
good connection.
(c) All electrical
switches located in wet places shall be mounted in weatherproof switch boxes or
cabinets in accordance with standards approved by the Department, and shall be
grounded.
(d) All permanent
installations of underground lighting or power circuits shall be installed and
maintained in accordance with standards approved by the Department. All wiring
shall be strung on standard insulated supports, six and one-half feet (6-1/2)
or more above the floor or travelways, or in the event this height is not
available, the wiring shall be in conduit or properly guarded; provided that
armored cable may be buried at least six (6") inches deep and markers installed
not less than two hundred (200') feet apart, and closer where necessary to show
changes in direction.
(e)
Switchboards shall consist of a substantial framework of iron pipe or
structural steel, on which shall be mounted a panel or panels of incombustible
non-absorbent insulating material, or other material according to the standards
of the Department, that is mechanically strong and has insulation qualities
suitable for the voltages at which it is used. All switchboard mountings,
instrument transformers and meter casings shall be grounded.
(f) Portable extension lamps shall be guarded
by a heavy wire cage which completely incloses both lamp and socket, and shall
be provided with a handle of insulating material to which both cage and socket
are firmly attached and through which the wire supplying the current is
carried. The socket shall be keyless and the lamp circuit shall be protected by
a fuse. Extension lamps shall be wired with heavy flexible rubber insulated
cord. It is recommended that low-voltage be used for portable extension
lamps.
(5)
Rules for Repair Works on Electrical Equipment - The
following safety rules shall be complied with in all electrical work in and
around mines:
1. Do not permit any work to be
begun on any electrically operated machinery until the control switch has first
been locked in the "off" position, and properly tagged by the person doing the
work.
2. Do not change any wiring
or connections while the circuit is "live" unless absolutely necessary. All
electrical work, so far as it is possible to do so, shall be done on days when
the mine is not in operation. Whenever circuits are opened for repairs,
alterations, or examinations, the disconnecting switches or cut outs shall also
be opened as an additional safeguard against accidental closing of the circuit
or the circuit may be locked open and the wires short circuited or grounded.
The workman responsible for having the circuit opened shall place on a
controlling switch a tag bearing his name and a notice that the switch shall
not be closed until the tag is removed. No person, shall be allowed to remove
the tag.
(a) Circuits having in excess of
five hundred (500) volts potential shall be carried inside metal conduit or
metallic sheathing or other protective covering recommended by the manufacture.
Such circuit, conduit or sheathing shall be electrically continuous and
effectively grounded.
(6)
Electrical Installation
Requirements - Underground electrical stations shall be so
constructed as to allow clearance for passing all electrical equipment where
such passing is permitted. They shall be of fireproof construction,
well-lighted, as dry as conditions permit, provided with a floor affording
secure footing, and where feasible, ventilated by a separate air split.
(a) Underground transformer stations shall in
addition be designed so that oil escaping from transformers will be retained
within the station.
(b) Any
transformers installed underground after the effective date of these rules,
unless they contain nonflammable, non-explosive transformer fluid, shall be in
a fireproof enclosure as near gas tight as possible, provided that such
enclosure shall have openings for ventilation and provision shall be made for
the automatic closing of such openings in case of fire within the
enclosure.
(c) Switchboards shall
be located as to allow a space of at least three (3') feet in front and in back
of them.
(d) All underground
electric stations shall be completely fenced or walled in and provided with a
substantial good fitting door or gate.
(e) Danger signs shall be conspicuously
placed at all such stations. All electric circuits entering any mine shall be
protected by lightning arresters.
Author: Marcus Davis, Workers' Compensation
Examiner.
