46 CFR § 111.51-3 - Short-circuit calculations for systems below 1500 kilowatts.

---
identifier: "/us/cfr/t46/s111.51-3"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 111.51-3 - Short-circuit calculations for systems below 1500 kilowatts."
title_number: 46
title_name: "Shipping"
section_number: "111.51-3"
section_name: "Short-circuit calculations for systems below 1500 kilowatts."
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"
---


# 111.51-3 Short-circuit calculations for systems below 1500 kilowatts.

The following short-circuit assumptions must be made for a system with an aggregate generating capacity below 1500 kilowatts, unless detailed computations in accordance with § 111.51-4 are submitted:

(a) The maximum short-circuit current of a direct current system must be assumed to be 10 times the aggregate normal rated generator currents plus 6 times the aggregate normal rated currents of all motors that may be in operation.

(b) The maximum asymmetrical short-circuit current for an alternating current system must be assumed to be 10 times the aggregate normal rated generator currents plus 4 times the aggregate normal rated currents of all motors that may be in operation.

(c) The average asymmetrical short circuit current for an alternating-current system must be assumed to be 8
1/2 times the aggregate normal rated generator currents plus 3
1/2 times the aggregate normal rated currents of all motors that may be in operation.