---
kind: "section"
citation: "46 C.F.R. § 161.013-5"
title: "46"
number: "161.013-5"
heading: "Intensity requirements."
url: "https://uscodex.org/cfr/46/161.013-5"
---

# §161.013-5. Intensity requirements.

- (a) If an electric light emits light over an arc of the horizon of 360 degrees, the light must:
  - (1) When level, have a peak intensity within 0.1 degrees of the horizontal plane;
  - (2) Have a peak Equivalent Fixed Intensity of at least 75 cd; and,
  - (3) Have a minimum Equivalent Fixed Intensity within a vertical divergence of ±3 degrees of at least 15 cd.
- (b) If an electric light emits a directional beam of light, the light must:
  - (1) Have an Equivalent Fixed Intensity of no less than 25 cd within ±4 degrees vertical and ±4 degrees horizontal divergence centered about the peak intensity; and,
  - (2) **Have a minimum peak Equivalent Fixed Intensity of 2,500 cd.**
- (c) The Equivalent Fixed Intensity (EFI) is the intensity of the light corrected for the length of the flash and is determined by the formula:
- (d) An electric light which meets the requirements of either paragraph [(a)](#a) or [(b)](#b) of this section need not, if capable of operating in both manners, meet the requirements of the other paragraph.

## Notes

### Source

Source: CGD 76-183a, 44 FR 73054, Dec. 17, 1979, unless otherwise noted.

### Authority

Authority: 46 U.S.C. 3306, 3703, 4302; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; DHS Delegation 00170.1, Revision No. 01.4.