| Full title | Fibre-optic communication subsystem test procedures. Part 4-5: Installed cabling plant. Attenuation measurement of MPO terminated fibre optic cabling plant using test equipment with MPO interfaces |
| Publisher | IEC, subcommittee SC 86C |
| Current edition | Edition 1.0 (2020-07) with Corrigendum 1 (2022-01). Stability date 2027 |
| European version | EN IEC 61280-4-5:2020, with corrigendum 2022 |
| Status | Current. First edition |
| Related standards | IEC 61280-4-1, IEC 61280-4-2, IEC 61300-3-35, ISO/IEC 14763-3 |
What it covers
IEC 61280-4-5 sets out how to measure the attenuation of installed fibre cabling that is terminated with MPO connectors at both ends. The test equipment itself has an MPO interface. The standard also covers determining polarity and length.
The cabling can include fibre, connectors, adapters, splices and other passive devices. It applies to residential, commercial, industrial, data centre and outside plant installations. It does not cover cabling that is not exclusively MPO to MPO.
| Fibre | Categories named in the scope | Test wavelengths |
|---|---|---|
| Multimode 50/125 µm | A1-OM2 to A1-OM5 to IEC 60793-2-10 | 850 nm. 1300 nm is optional |
| Single-mode 9/125 µm | B-652 and B-657 to IEC 60793-2-50 | 1310 nm and/or 1550 nm |
The scope explains the wavelength choice. Parallel optics transceivers with an MPO interface operate at 850 nm for multimode, and at 1310 nm or 1550 nm for single-mode. Other fibre categories can also be measured with a light source and power meter (LSPM) or an OTDR that uses an internal or external optical switch with one MPO interface.
Test methods
The standard has five normative test methods, each in its own annex. Four use an LSPM. One uses an OTDR.
| Annex | Method | Type |
|---|---|---|
| A | One-cord method | LSPM |
| B | Three-cord method | LSPM |
| C | Adapter-cord method | LSPM |
| D | Equipment cord method | LSPM |
| E | Optical time domain reflectometer | OTDR |
Clause 4.2 relates cabling configurations to the applicable test methods (Tables 1 and 2). The annex procedures are split by whether each end of the cabling is pinned or unpinned, and whether the power meter is pinned or unpinned. For example, Annex A has procedures for unpinned to unpinned, unpinned to pinned and pinned to pinned cabling, plus a procedure that uses a gender-neutral test cord. Annex B also includes a channel test procedure.
Clause 7.2.6 covers multi-fibre and bi-directional testing.
Apparatus
- Light source, with stability requirements (6.2.2) and spectral requirements (Table 8). Annex F (normative) sets requirements for the multimode source characteristics.
- Launch cord, receive or tail cord, substitution cord and adapter cord.
- Power meter (LSPM methods only).
- OTDR apparatus, which can use an external optical switch.
- End face cleaning and inspection equipment. End faces are inspected to IEC 61300-3-35.
IEC 61315 (power meter calibration) and IEC 61746-1 and -2 (OTDR calibration) are normatively referenced.
Test cords and uncertainty
Clause 5 lists the main sources of uncertainty, including the power meter and the connector grade of the test cords. Table 3 gives the measurement bias related to test cord connector grade. Typical uncertainty values are given for multimode testing at 850 nm and single-mode testing at 1310 nm, for the same photodetector and for different photodetectors.
Annex I (normative) covers the use of low attenuation grade test cords. It gives a measurement bias adjustment for LSPM methods (Table I.1) and an acceptance figure adjustment for the OTDR method (Table I.2). Worked examples cover the one-cord method and the equipment cord method. It also covers the effect of reference grade test cords on OTDR results.
Annex H (informative) gives procedures to verify the attenuation of test cords, breakout cords and cassettes, including verification of test cords before the cabling is measured.
OTDR testing
Annex E covers OTDR measurement, including how to locate the connections and define the power levels used in the calculation, and OTDR uncertainties. Informative Annex G gives OTDR configuration information. It includes measurement with low return loss connectors or short cabling, and measurement with APC MPO connections.
Related standards
| Standard | Relationship |
|---|---|
| IEC 61280-4-1 | Multimode attenuation measurement. Normatively referenced, dated 2019 edition |
| IEC 61280-4-2 | Single-mode attenuation and optical return loss measurement |
| IEC 61280-1-3 | Central wavelength and spectral width measurement. Normatively referenced |
| IEC 61300-3-35 | End face visual inspection. Normatively referenced |
| IEC 60825 series | Safety of laser products. Normatively referenced |
| ISO/IEC 14763-3 | Testing of optical fibre cabling. References IEC 61280-4-5 |
What it means in practice
- Use IEC 61280-4-5 when both ends of the cabling are MPO and the tester has an MPO port. Cabling with other connectors at one end is outside its scope.
- Check the test report names the method (one-cord, three-cord, adapter-cord, equipment cord or OTDR) and whether ends were pinned or unpinned.
- Check the wavelengths match the application: 850 nm for multimode parallel optics, 1310 nm and/or 1550 nm for single-mode.
- Check the test cord grade, and whether the limit has been adjusted for low attenuation grade cords as Annex I describes.
- Check that polarity was verified as well as attenuation.
- Record the information Clause 9 requires for each test.
Related reading: Fibre optic loss budget: how to calculate insertion loss · Fibre insertion loss and return loss explained.