---
kind: "section"
citation: "49 C.F.R. § 238.225"
title: "49"
number: "238.225"
heading: "Electrical system."
url: "https://uscodex.org/cfr/49/238.225"
---

# §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.

## Notes

### Authority

Authority: 49 U.S.C. 20103, 20107, 20133, 20141, 20302-20303, 20306, 20701-20702, 21301-21302, 21304; 28 U.S.C. 2461 note; and 49 CFR 1.89.

### Source

Source: 64 FR 25660, May 12, 1999, unless otherwise noted.