46 CFR § 111.51-2 - Short-circuit calculations.

---
identifier: "/us/cfr/t46/s111.51-2"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 111.51-2 - Short-circuit calculations."
title_number: 46
title_name: "Shipping"
section_number: "111.51-2"
section_name: "Short-circuit calculations."
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"
---


# 111.51-2 Short-circuit calculations.

(a) The available short-circuit current must be computed—

(1) From the aggregate contribution of all generators that can simultaneously operate in parallel;

(2) From the largest probable motor load; and

(3) With a three-phase fault on the load terminals of the protective device.

(b) The calculated currents must be used to select suitably rated equipment and to allow the selection and setting of protective devices.