---
kind: "section"
citation: "46 C.F.R. § 111.51-3"
title: "46"
number: "111.51-3"
heading: "Short-circuit calculations for systems below 1500 kilowatts."
url: "https://uscodex.org/cfr/46/111.51-3"
---

# §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](/cfr/46/111.51-4.md) 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.

## Notes

### Source

Source: USCG-2020-0075, 88 FR 16362, Mar. 16, 2023, unless otherwise noted.

### Authority

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.

### Source

Source: CGD 74-125A, 47 FR 15236, Apr. 8, 1982, unless otherwise noted.