[Code of Federal Regulations]
[Title 49, Volume 4]
[Revised as of October 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR238.225]

[Page 565]
 
                        TITLE 49--TRANSPORTATION
 
       CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF 
                             TRANSPORTATION
 
PART 238--PASSENGER EQUIPMENT SAFETY STANDARDS--Table of Contents
 
     Subpart C--Specific Requirements for Tier I Passenger Equipment
 
Sec. 238.225  Electrical system.

    All passenger equipment shall comply with the following:
    (a) Conductors. Conductor sizes shall be selected on the basis of 
current-carrying capacity, mechanical strength, temperature, flexibility 
requirements, and maximum allowable voltage drop. Current-carrying 
capacity shall be derated for grouping and for operating temperature.
    (b) Main battery system.
    (1) The main battery compartment shall be isolated from the cab and 
passenger seating areas by a non-combustible barrier.
    (2) Battery chargers shall be designed to protect against 
overcharging.
    (3) If batteries are of the type to potentially vent explosive 
gases, the battery compartment shall be adequately ventilated to prevent 
the accumulation of explosive concentrations of these gases.
    (c) Power dissipation resistors.
    (1) Power dissipating resistors shall be adequately ventilated to 
prevent overheating under worst-case operating conditions as determined 
by the railroad.
    (2) Power dissipation grids shall be designed and installed with 
sufficient isolation to prevent combustion.
    (3) Resistor elements shall be electrically insulated from resistor 
frames, and the frames shall be electrically insulated from the supports 
that hold them.
    (d) Electromagnetic interference and compatibility. (1) The 
operating railroad shall ensure electromagnetic compatibility of the 
safety-critical equipment systems with their environment. 
Electromagnetic compatibility may be achieved through equipment design 
or changes to the operating environment.
    (2) The electronic equipment shall not produce electrical noise that 
affects the safe performance of train line control and communications or 
wayside signaling systems.
    (3) To contain electromagnetic interference emissions, suppression 
of transients shall be at the source wherever possible.
    (4) All electronic equipment shall be self-protected from damage or 
improper operation, or both, due to high voltage transients and long-
term over-voltage or under-voltage conditions. This includes protection 
from both power frequency and harmonic effects as well as protection 
from radio frequency signals into the microwave frequency range.