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ITU-T K.20 (04/2015)

Resistibility of telecommunication equipment installed in a telecommunication centre to overvoltages and overcurrents

Recommendation ITU-T K.20 specifies resistibility requirements and test procedures for telecommunication equipment that is attached to or installed within a telecommunication centre.

Overvoltages or overcurrents covered by this Recommendation include surges due to lightning on or near the line plant, short‑term induction from adjacent a.c. power lines or railway systems, earth potential rise due to power faults, direct contact between telecommunication lines and power lines and electrostatic discharges. The sources for overvoltages in internal lines, between equipment/racks, are mainly inductive coupling caused by lightning currents being conducted in nearby lightning strokes or lightning currents being conducted in nearby conductors.

Major changes compared with the 2008 version of this Recommendation include:

• updated references;

• added information on which universal serial bus (USB) ports should be tested;

• added information on when to add protection to untested ports;

• added test requirements for external coaxial cable ports;

• added test requirements for multiple conductor internal unshielded cable ports.

Major changes compared with the 2011 version of this Recommendation include:

• added test requirements for unshielded twisted pair (UTP) Ethernet;

• added test requirements for shielded twisted pair STP Ethernet;

• added test requirements for power over Ethernet (PoE);

• added STP shield testing.

Citation:	https://handle.itu.int/11.1002/1000/12403
Series title:	K series: Protection against interference
Approval date:	2015-04-22
Approval process:	AAP
Status:	Superseded
Maintenance responsibility:	ITU-T Study Group 5
Further details:	Patent statement(s) Development history [8 related work items in progress]

Ed.	ITU-T Recommendation	Status	Summary	Table of Contents	Download
18	K.20 (11/2022)	In force	here	here	here
17	K.20 (06/2021)	Superseded	here	here	here
16	K.20 (11/2019)	Superseded	here	here	here
15	K.20 (07/2019)	Superseded	here	here	here
14	K.20 (10/2018)	Superseded	here	here	here
13	K.20 (07/2017)	Superseded	here	here	here
12	K.20 (12/2016)	Superseded	here	here	here
11	K.20 (06/2016)	Superseded	here	here	here
10	K.20 (04/2015)	Superseded	here	here	here
9	K.20 (11/2011)	Superseded	here	here	here
8	K.20 (04/2008)	Superseded	here	here	here
7.1	K.20 (2003) Amd. 1 (11/2004)	Superseded	-	here	here
7	K.20 (07/2003)	Superseded	here	here	here
7.0	K.20 (2003) Err. 1 (01/2004)	Superseded	-	-	here
6	K.20 (02/2000)	Superseded	here	here	here
5	K.20 (10/1996)	Superseded	-	-	here
4	K.20 (03/1993)	Superseded	-	here	here
3	K.20 (03/1991)	Superseded	-	here	here
2	K.20 (11/1988)	Superseded	-	here	here
1	K.20 (10/1984)	Superseded	-	-	Not available


ITU-T Supplement	Title	Status	Summary	Table of contents	Download
K Suppl. 3 (10/2015)	ITU-T K.20, K.21, K.45, K.82 – Additional criteria to protect telecommunication cabling during a power cross event	In force	here	here	here
K Suppl. 8 (11/2017)	Resistibility analysis of 5G systems	In force	here	here	here
K Suppl. 9 (05/2019)	5G technology and human exposure to radiofrequency electromagnetic fields	In force	here	here	here
K Suppl. 10 (11/2017)	Analysis of electromagnetic compatibility aspects and definition of requirements for 5G mobile systems	In force	here	here	here
K Suppl. 13 (12/2021)	Radiofrequency electromagnetic field (RF-EMF) exposure levels from mobile and portable devices during different conditions of use	In force	here	here	here
K Suppl. 14 (09/2019)	The impact of RF-EMF exposure limits stricter than the ICNIRP or IEEE guidelines on 4G and 5G mobile network deployment	In force	here	here	here
K Suppl. 15 (09/2018)	ITU-T K.20, K.21 and K.44 – Internal DC powering interface surge testing factors	In force	here	here	here
K Suppl. 16 (10/2022)	Electromagnetic field compliance assessments for 5G wireless networks	In force	here	here	here
K Suppl. 19 (09/2019)	Electromagnetic field (EMF) strength inside underground railway trains	In force	here	here	here
K Suppl. 24 (07/2022)	ITU-T K.20 – Rationale for setting resistibility requirements of telecommunication equipment installed in a telecommunication centre against lightning	In force	here	here	here
K Suppl. 29 (07/2022)	Electromagnetic field strength inside and outside of electric vehicles using wireless power transfer technology	In force	here	here	here
K Suppl. 32 (06/2023)	Case studies of radio frequency- electromagnetic field (RF-EMF) assessment	In force	here	here	here

Title	Approved on	Download
Guide on the use of the overvoltage resistibility for Recommendations ITU-T K.20, K.21 and K.45	2023-11-22
Guide on the use of the overvoltage resistibility for Recommendations ITU-T K.20, K.21 and K.45	2012-04-19	here

Title	Approved on	Download
Mitigation measures for telecommunication installations – Chapter 10	2006	here
Mitigation measures for telecommunication installations	2004	here
Earthing and bonding	2003	here
Guide to the use of ITU-T Publications produced by Study Group 5 aimed at achieving Electromagnetic Compatibility and Safety	2002	here
ISDN field trial guidelines	1991	here
Earthing of telecommunication installations	1976	here

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ITU-T K.20 (04/2015)