Uniformat D5010

Transformer, pad-mounted liquid-filled

Also called pad mount transformer

• Confidence C
• Version 0.3.0 (permanent link)
• Reviewed 2026-10-22

This is version 0.3.0. The latest is 0.4.0.

Service life

Years in service. The band runs from the shortest to the longest life the sources state, so it shows how much they disagree, not how long 80% of units last. The line is the median of the stated lives.

Basis

• 30 years · CNA e-Tool Estimated Useful Life Table, p3 · HUD CNA 3.2.8.2.3 “Transformer” — U.S. Department of Housing and Urban Development (planning life)
  Same life for family and elderly properties. US multifamily housing. HUD's row is a site electric utility transformer.
• 45 years · Handbook for Optimised Deprival Valuation of System Fixed Assets of Electricity Lines Businesses, 30 August 2004, p37 · Table A.1 “DISTRIBUTION TRANSFORMERS – Ground Mounted, Single/Two Phase, 22/0.4 and 11/0.4 kV, Cable Entry – 22/0.4 kV, 100 kVA to 1,500 kVA” — Commerce Commission (New Zealand) (accounting life)
  Printed page 35. Ground-mounted (pad-type) distribution transformers of an electricity network, oil-filled in NZ practice; all eight sizes 100-1,500 kVA have Standard Life 45 years. Heading printed as 'Single/Two Phase'. Utility network assets (2004). Regulatory valuation for electricity lines businesses, superseded as a valuation method by the Commerce Commission's Input Methodologies (from 2010). Only the ground-mounted distribution transformer rows map to a library component.
• 45 years · Handbook for Optimised Deprival Valuation of System Fixed Assets of Electricity Lines Businesses, 30 August 2004, p37 · Table A.1 “DISTRIBUTION TRANSFORMERS – Ground Mounted, Single/Two Phase, 22/0.4 and 11/0.4 kV, Cable Entry – 11/0.4 kV, 100 kVA to 1,500 kVA” — Commerce Commission (New Zealand) (accounting life)
  Printed page 35. As the 22/0.4 kV row; all eight sizes 100-1,500 kVA have Standard Life 45 years. Utility network assets (2004). Regulatory valuation for electricity lines businesses, superseded as a valuation method by the Commerce Commission's Input Methodologies (from 2010). Only the ground-mounted distribution transformer rows map to a library component.
• 35 years · Design standards: employer's requirements – Technical Manual (ER-DFE-XX-XX-T-X-0201, revision A-C01), p275 · 5.7.4 “High voltage (HV) switchgear, transformers and packaged substations: 35 years” — Department for Education (England) (design life)
  Printed page 275. HV transformers on a school site (packaged substations); type not stated. Minimum life expectancy (design requirement) for DfE-funded school buildings. Minimum design requirements placed on contractors for school buildings, not observed replacement ages. Section 5.1.4 (sanitaryware) refers to CIBSE Guide M Appendix 12.A1 'in general'.
• 32 years · Energy Conservation Program: Energy Conservation Standards for Distribution Transformers (final rule), 89 FR 29834, April 22, 2024, p113 · IV.F.8 “Transformer Service Lifetime: "a distribution of lifetimes, with an estimated average of 32 years and a maximum of 60 years"” — U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (planning life)
  Printed page 29946. Covers all distribution transformers, including low-voltage dry-type (building dry-type) and medium-voltage liquid-immersed (pad-mounted). Mean of a distribution; the maximum is 60 years. Same value also stated on p.5 (printed 29838) and in Table IV summary on p.101 (printed 29934).
• 25 years · General depreciation rates (IR265), July 2021, p34 · POWR “Transformers” — Inland Revenue (Te Tari Taake), New Zealand (accounting life)
  Printed page 34. Power generation and electrical reticulation category; type not stated. Also 'Transformers 25' under ELEC p.15. Printed DV 8%, SL 6%. Tax depreciation lives set by the Commissioner of Inland Revenue for New Zealand income tax, not engineering or asset-management lives; they are banded and often short (e.g. reticulation piping 25 years). The July 2021 edition was the newest PDF reachable; the online Depreciation Rate Finder may hold later determinations.

How sources are chosen and recorded: sourcing policy.

Preventive maintenance

9 tasks in 2 work orders. Intervals that fall due together are one visit: the every 2 years visit also covers the annual tasks.

1. 1
2. 2
3. 3
4. 4
5. 5
6. 6
7. 7
8. 8
9. 9
10. 10
11. 11
12. 12Annual

Months from the schedule start. Download the tasks as CSV for a CMMS, or ask the MCP tool get_pm_schedule for dated visits.

Frequencies are ISO 8601 durations in the data (P3M = every 3 months).

Open questions

• Every source here is a published planning, design or accounting life. None is observed replacement data.
• Some maintenance intervals come from TM 5-692-1, an Army manual for mission-critical (C4ISR) facilities; they may be tighter than typical commercial practice.

Know the answer? Send it with a source to [email protected].

Cite this

Citation

unfinished.one (2026). Transformer, pad-mounted liquid-filled, v0.3.0. https://unfinished.one/c/transformer-pad-mounted/v/0.3.0

BibTeX

@misc{unfinished_transformer_pad_mounted_0_3_0,
  title = {Transformer, pad-mounted liquid-filled},
  author = {{unfinished.one}},
  year = {2026},
  version = {0.3.0},
  url = {https://unfinished.one/c/transformer-pad-mounted/v/0.3.0},
  note = {CC BY 4.0}
}

Licence CC BY 4.0 · How to cite · JSON · Versions: 0.4.0, 0.3.0, 0.2.0, 0.1.0