{"id":"transformer-dry","version":"0.3.0","classification":{"uniformat":"D5010"},"names":["Transformer, dry-type"],"aliases":["dry type transformer","XFMR","transformer"],"service_life":{"median_years":32,"range_years":[25,35],"range_basis":"source_spread"},"pm_tasks":[{"task":"Check warning signs are in place","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Inspect enclosure for damage, openings and corrosion","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Clear blocked air passages","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Investigate unusual odors","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Inspect electrical connections for degradation and tightness","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Inspect insulation for discoloration","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Inspect equipment grounding conductors and connections","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Check indicating lights","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Clean equipment","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Tighten electrical connections","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Verify equipment grounding","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Infrared scan","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":173,"checklist":"Table 21-1 Typical secondary distribution maintenance"},{"task":"Inspect solid insulation for discoloration","frequency":"P6M","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":176,"checklist":"Table 21-3 Secondary system transformers"},{"task":"Inspect forced cooling equipment","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":176,"checklist":"Table 21-3 Secondary system transformers"},{"task":"Test cooling fans by simulating high temperature","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":176,"checklist":"Table 21-3 Secondary system transformers"},{"task":"Verify transformer alarms","frequency":"P1Y","reference":"TM 5-692-1 Maintenance of Mechanical and Electrical Equipment at Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance (C4ISR) Facilities: Recommended Maintenance Practices","url":"https://www.wbdg.org/FFC/ARMYCOE/COETM/tm_5_692_1.pdf","page":176,"checklist":"Table 21-3 Secondary system transformers"}],"basis":[{"type":"public_document","life_type":"design","title":"Design standards: employer's requirements – Technical Manual (ER-DFE-XX-XX-T-X-0201, revision A-C01)","by":"Department for Education (England)","url":"https://assets.publishing.service.gov.uk/media/6971f649d8adeaf266040501/ER-DFE-XX-XX-T-X-0201-Technical_Manual-A-C01.pdf","page":275,"code":"5.7.4","label":"High voltage (HV) switchgear, transformers and packaged substations: 35 years","years":35,"note":"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'."},{"type":"public_document","life_type":"planning","title":"Energy Conservation Program: Energy Conservation Standards for Distribution Transformers (final rule), 89 FR 29834, April 22, 2024","by":"U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy","url":"https://www.govinfo.gov/content/pkg/FR-2024-04-22/pdf/2024-07480.pdf","page":113,"code":"IV.F.8","label":"Transformer Service Lifetime: \"a distribution of lifetimes, with an estimated average of 32 years and a maximum of 60 years\"","years":32,"note":"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)."},{"type":"public_document","life_type":"accounting","title":"General depreciation rates (IR265), July 2021","by":"Inland Revenue (Te Tari Taake), New Zealand","url":"https://www.ird.govt.nz/-/media/project/ir/home/documents/forms-and-guides/ir200---ir299/ir265/ir265-2021.pdf","page":34,"code":"POWR","label":"Transformers","years":25,"note":"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."}],"confidence":{"grade":"C","sample_size":null},"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."],"contributors":["unfinished.one editors"],"last_reviewed":"2026-10-22","canonical_url":"https://unfinished.one/c/transformer-dry","versioned_url":"https://unfinished.one/c/transformer-dry/v/0.3.0","licence":"CC-BY-4.0","citation":"unfinished.one (2026). Transformer, dry-type, v0.3.0. https://unfinished.one/c/transformer-dry/v/0.3.0"}