---
kind: "section"
citation: "10 C.F.R. § 429.47"
title: "10"
number: "429.47"
heading: "Distribution transformers."
url: "https://uscodex.org/cfr/10/429.47"
---

# §429.47. Distribution transformers.

- (a) **Sampling plan for selection of units for testing.**
  - (1) The requirements of [§ 429.11](/cfr/10/429.11.md) are applicable to distribution transformers; and
  - (2) For each basic model of distribution transformer, efficiency must be determined either by testing, in accordance with [§ 431.193](/cfr/10/431.193.md) and the provisions of this section, or by application of an AEDM that meets the requirements of [§ 429.70](/cfr/10/429.70.md) and the provisions of this section.
    - (i) **For each basic model selected for testing—**
      - (A) If the manufacturer produces five or fewer units of a basic model over 6 months, each unit must be tested. A manufacturer may not use a basic model with a sample size of fewer than five units to substantiate an AEDM pursuant to [§ 429.70](/cfr/10/429.70.md).
      - (B) If the manufacturer produces more than five units over 6 months, a sample of at least five units must be selected and tested.
    - (ii) Any represented value of efficiency of a basic model must satisfy the condition:
- (b) **Certification reports.**
  - (1) The requirements of [§ 429.12](/cfr/10/429.12.md) are applicable to distribution transformers except that required information in [paragraph (b)](#b) of this section may be reported by kVA grouping instead of by basic model and paragraph (b)(6) of this section does not apply; and
  - (2) Pursuant to [§ 429.12(b)(13)](/cfr/10/429.12.md?p=b-13), a certification report shall include the following public product-specific information: For the most and least efficient basic models within each “kVA grouping” for which [part 431](/cfr/10/part431.md) prescribes an efficiency standard, the kVA rating, the insulation type (i.e., low-voltage dry-type, medium-voltage dry-type or liquid-immersed), the number of phases (i.e., single-phase or three-phase), and the basic impulse insulation level (BIL) group rating (for medium-voltage dry-types).
- (c) **Alternative methods for determining efficiency or energy use—** for distribution transformers can be found in [§ 429.70](/cfr/10/429.70.md) of this subpart.
- (d) **Kilovolt ampere (kVA) grouping.** As used in this section, a “kVA grouping” is a group of basic models which all have the same kVA rating, have the same insulation type (i.e., low-voltage dry-type, medium-voltage dry-type or liquid-immersed), have the same number of phases (i.e., single-phase or three-phase), and, for medium-voltage dry-types, have the same BIL group rating (i.e., 20-45 kV BIL, 46-95 kV BIL or greater than or equal to96 kV BIL).

## Notes

### Authority

Authority: 42 U.S.C. 6291-6317; 28 U.S.C. 2461 note.

### Source

Source: 76 FR 12451, Mar. 7, 2011, unless otherwise noted.