Data record `instr.loop-impedance-tester.four-wire-and-resolution`

Verified 2026-10-27 Confidence: High

At the finest resolution offered by two-wire loop testers the contact resistance of the probe tips, which changes with the pressure the operator applies, becomes a noticeable part of a very low loop impedance; four-wire voltage sensing applies the load current through one pair of connections and senses the voltage through a separate pair, so that the probe contact resistance is kept out of the result.

Provenance. Where this record comes from and where it is used: the cited source, the record itself and the entry that cites it.

Provenance: the chain from source to entry.
Step	Item	Detail
Source	Megger Electrical Tester article	Manufacturer page
Data record	instr.loop-impedance-tester.four-wire-and-resolution	Verified 2026-10-27
Entry	Loop impedance tester	No revisions

Subject: Loop impedance tester (Instrument classes)
Kind: Instrument fact
Source: Megger Electrical Tester article, 2018-07-13 edition, The many facets of loop testing, Megger. Publisher page

History

Every recorded change to this data record, oldest first.
Date	Change
2026-10-27	created
2026-10-27	revised
2026-10-27	review_status unreviewed -> software_reviewed

Cite this page

Cite the governing standard for the fact itself; cite this page as the finding aid.

"Data record instr.loop-impedance-tester.four-wire-and-resolution." Test Instrument Reference. 2026-10-27. https://www.testinstrumentreference.com/data/instr.loop-impedance-tester.four-wire-and-resolution/.

Test Instrument Reference, Data record instr.loop-impedance-tester.four-wire-and-resolution (Oct. 27, 2026), https://www.testinstrumentreference.com/data/instr.loop-impedance-tester.four-wire-and-resolution/.

@misc{etr-data-instr-loop-impedance-tester-four-wire-and-resolution,
  title = {Data record instr.loop-impedance-tester.four-wire-and-resolution},
  howpublished = {\url{https://www.testinstrumentreference.com/data/instr.loop-impedance-tester.four-wire-and-resolution/}},
  organization = {Test Instrument Reference},
  publisher = {Test Instrument Reference},
  year = {2026},
  note = {last substantive change 2026-10-27}
}

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