46 CFR § 111.51-5 - Protection of vital equipment.

---
identifier: "/us/cfr/t46/s111.51-5"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 111.51-5 - Protection of vital equipment."
title_number: 46
title_name: "Shipping"
section_number: "111.51-5"
section_name: "Protection of vital equipment."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "J"
subchapter_name: "ELECTRICAL ENGINEERING"
part_number: "111"
part_name: "ELECTRIC SYSTEMS—GENERAL REQUIREMENTS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "46 U.S.C. 3306, 3703; DHS Delegation No. 00170.1, Revision No. 01.2. Section 111.05-20 and Subpart 111.106 also issued under sec. 617, Pub. L. 111-281, 124 Stat. 2905."
regulatory_source: "CGD 74-125A, 47 FR 15236, Apr. 8, 1982, unless otherwise noted."
cfr_part: "111"
---


# 111.51-5 Protection of vital equipment.

(a) The coordination of overcurrent protective devices must be demonstrated for all potential plant configurations.

(b) Protective relays and overcurrent protective devices must be installed so that:

(1) A short-circuit on a circuit that is not vital to the propulsion, control, or safety of the vessel does not trip equipment that is vital; and

(2) A short-circuit on a circuit that is vital to the propulsion, control, or safety of the vessel is cleared only by the protective device that is closest to the point of the short-circuit.