Program Policy Manual - VOLUME V - Mine Safety and Health ...

MSHA PROGRAM POLICY MANUAL VOLUME V
Any fire sensor and warning device system installed in a return
airway must be approved as permissible by the Approval and
Certification Center under Part 23. An approval under Part 23
requires that only components specified in the approval may be
used with the system unless authorization for the use of
different components has been obtained from the Approval and
Certification Center by the mine operator. The unauthorized
substitution of components different from those which were
specified in the approval of a permissible fire sensor and
warning device system used on a belt conveyor in a return
airway shall be cited as a violation of Section 75.1103-7(b).
Some coal mines have intermixed heat sensors and heat sensor
cables with reverse conductor color codes in the same polarized
fire sensor and warning device system. Therefore, heat sensors
which are polarized so that the white conductor must be
positive have been installed in heat sensor cables which are
polarized so the black conductor must be positive. Likewise,
heat sensor cables which are polarized so that the white
conductor must be positive have been connected to heat sensor
cables which are polarized so that the black conductor must be
positive.
If the colors are matched when splicing heat sensors and heat
sensor cables with one conductor color code into heat sensor
cables of the opposite conductor color code in accordance with
customary electrical practice (black to black, white to white),
the system will malfunction and no audible or visual signal
will appear at the control station when an improperly polarized
heat sensor(s) is activated. Although it is possible to
correctly intermix heat sensors and heat sensor cables of
opposite conductor color codes in polarized fire sensor and
warning device systems, the potential confusion created by the
differences in conductor color codes could create a safety
hazard. Even if assurances are given that initial installation
will be done in accordance with instructions to splice black to
white conductors, there can be no satisfactory assurance that
later maintenance will always be performed correctly because
the method is contrary to common practice. Therefore, the use
of heat sensors and heat sensor cables with opposite conductor
color codes within the same polarized fire sensor and warning
device system is not acceptable under Section 75.1103-2.
Enforcement personnel should recognize that it is not important
which conductor color code is used in a polarized fire sensor
and warning device system as long as the conductor color code
and polarity of all heat sensors and heat sensor cables within
the system are the same and the polarity of the heat sensors
October 2003 (Release V-34) 105