[Code of Federal Regulations]
[Title 49, Volume 4]
[Revised as of October 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR236.2]

[Page 490]
 
                        TITLE 49--TRANSPORTATION
 
       CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF 
                             TRANSPORTATION
 
 PART 236--RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND 
APPLIANCES--Table of Contents
 
             Subpart A--Rules and Instructions: All Systems
 
Sec. 236.2  Grounds.

    Each circuit, the functioning of which affects the safety of train 
operations, shall be kept free of any ground or combination of grounds 
which will permit a flow of current equal to or in excess of 75 percent 
of the release value of any relay or other electromagnetic device in the 
circuit, except circuits which include any track rail and except the 
common return wires of single-wire, single-break, signal control 
circuits using a grounded common, and alternating current power 
distribution circuits which are grounded in the interest of safety.