---
kind: "section"
citation: "49 C.F.R. § 236.2"
title: "49"
number: "236.2"
heading: "Grounds."
url: "https://uscodex.org/cfr/49/236.2"
---

# §236.2. Grounds.

- (a) **General.** Except as provided in [paragraph (b)](#b) of this section, each circuit, the functioning of which affects the safety of train operations, shall be kept free of any ground or combination of grounds having a current flow of 75 percent or more of the value necessary to retain a permissive state of a safety appliance.
- (b) **Exception.** [Paragraph (a)](#a) of this section does not apply to the following:
  - (1) Circuits that include any track rail;
  - (2) The common return wires of single-wire, single-break, and signal control circuits using a grounded common;
  - (3) Circuitry internal to microprocessor-based appliances;
  - (4) Circuitry internal to semiconductor-based memory; or
  - (5) **Alternating current power distribution circuits that are grounded in the interest of safety.**

## Notes

### Amendments

[79 FR 49715, Aug. 22, 2014]

### Authority

Authority: 49 U.S.C. 20102-20103, 20107, 20133, 20141, 20157, 20301-20303, 20306, 20501-20505, 20701-20703, 21301-21302, 21304; 28 U.S.C. 2461 note; and 49 CFR 1.89.

### Source

Source: 33 FR 19684, Dec. 25, 1968, unless otherwise noted.

### Amendments

[79 FR 49715, Aug. 22, 2014]