FprEN IEC 60297-3-103:2026
(Main)Mechanical structures for electrical and electronic equipment - Dimensions of mechanical structures of the 482,6 mm (19 in) series - Part 3-103: Keying and alignment pin
- Status
- Not Published
- Publication Date
- 20-Dec-2026
- Technical Committee
- CLC/SR 48D - Mechanical structures for electronic equipment
- Current Stage
- 5060 - Voting results sent to TC, SR - Formal Approval
- Start Date
- 18-Sep-2026
- Completion Date
- 18-Sep-2026
FprEN IEC 60297-3-103:2026 is a draft European/IEC standard for the mechanical structures of 482,6 mm (19 in) electronic equipment. It specifies additional interface dimensions for keying and alignment pin features used with subracks and plug-in units, so matching modules can be inserted, guided, and optionally aligned or earth-connected correctly. Engineers, quality teams and buyers use it to check compatibility between rack hardware and plug-in units in the IEC 60297 19-inch system.
What does FprEN IEC 60297-3-103:2026 specify?
FprEN IEC 60297-3-103:2026 covers only the extra interface dimensions for a keying device and an alignment pin used with subracks and plug-in units according to IEC 60297-3-101. It also says the document may be used together with IEC 60297-3-102.
The document is organized into a short set of clauses:
- Scope and object
- Normative references
- Terms and definitions
- Arrangement overview for keying of plug-in units in a subrack
- Arrangement overview for alignment and/or electrical contact of a plug-in unit to a subrack
- Arrangement overview for a subrack guide rail and printed board with a 2,54 mm offset of the printed board reference plane
- Dimensions used in the figures
The structure matters in practice because the standard is mainly a dimensional interface document. It tells users where the relevant dimensions are defined and which companion parts provide the base 19-inch subrack geometry.
What are the key requirements of FprEN IEC 60297-3-103:2026?
FprEN IEC 60297-3-103:2026 focuses on preventing incorrect insertion, defining alignment features, and showing how the 19-inch interface changes when keying or an offset guide rail is used. The main clauses describe the physical arrangement, the programming of keys, and the inspection dimensions used to check the fit.
Keying of plug-in units in a subrack
Clause 4 says the keying method is intended to prevent misarrangement of board type plug-in units in subracks. The keys are to be snap-in mounted so they can be changed or retrofitted as needed. In practice, this means the keying parts are not just permanent geometry - they are configurable parts of the interface.
Clause 4.4 states that the key dimensions allow four positions within a subrack mounting chamber, and that the key shall be a self-retaining snap-in assembly. For users, that means the document supports coded interfaces rather than a single fixed orientation.
Clause 4.5 explains the programming logic for the keying chambers. Corresponding chambers on the subrack and the plug-in unit use the same letters, and a matching identification allows insertion, while a different identification blocks insertion. This is the core anti-misassembly function of the standard.
Clause 4 also distinguishes mounting heights: for 3U subracks, keying is recommended on the lower side only, while 6U and 9U need keying on both the upper and lower sides. That matters because the safe arrangement changes with the height of the subrack.
Alignment and/or electrical contact
Clause 5 says the alignment and/or electrical contact feature is used either to keep front panels at a controlled distance within a subrack or as an advanced contact to the receptacle in the subrack. In practice, that means the same interface can support mechanical positioning and contact function.
Clause 5.2 says the alignment pin receptacle may be an integrated part of the guide rail, and the hole provides guidance for the alignment pin. Within the defined area, an earth contact may be used optionally, and the electrical contact shall connect the alignment pin to the chassis ground of the subrack. This is important for designs that need alignment plus grounding through the rack interface.
Offset guide rail arrangement
Clause 6 describes a subrack guide rail with a 2,54 mm offset of the printed board reference plane. The offset does not change the position in the subrack, but it shifts the printed board groove to the right. This matters when a design must keep the same subrack position while changing the printed board location.
Clause 6 also says the rear-mounted guide rail is a mirror image, and that the arrangement may be combined with guide rails according to IEC 60297-3-101. That gives designers a way to reuse the same subrack family while adapting the board interface.
Inspection dimensions
Clause 4.6 and Clause 5.3 refer to inspection dimensions for checking the keying chamber and the alignment interface. Table 1 gives the chamber inspection dimensions for 3U, 6U and 9U arrangements, and the figures show the inspection points. For quality control, this is the part used to verify that the manufactured parts match the intended interface.
Dimensions used in the figures
Clause 7 defines the symbols used in the drawings, including U and H. U is the coordination height unit used in the 19-inch system, and H is used for mounting centre distances and vertical positioning centres for alignment pins and keys. That helps readers interpret the figures correctly during design and inspection.
What terms does FprEN IEC 60297-3-103:2026 define?
- Subrack - the 19-inch frame that receives plug-in units and carries the interface features described in this standard.
- Plug-in unit - the board or module inserted into the subrack, with keyed or aligned engagement features.
- Keying - the coded mechanical arrangement that allows the correct module to be inserted and blocks the wrong one.
- Alignment pin - the pin and receptacle arrangement used to guide a plug-in unit into position, and optionally provide earth contact.
- Guide rail - the rail that supports and guides the printed board type plug-in unit in the subrack.
- U - the coordination height unit used to identify 3U, 6U and 9U mounting chamber arrangements.
- H - the symbol used for mounting centre distances and vertical positioning centres in the figures.
Who uses FprEN IEC 60297-3-103:2026?
FprEN IEC 60297-3-103:2026 is used by designers of 19-inch subracks, plug-in units, guide rails and front panels in electrical and electronic equipment. It is also relevant to manufacturers and integrators of printed board type plug-in units, especially where keyed insertion, alignment, shielding gaskets or grounding contact are part of the design.
Quality and test engineers use it to inspect chamber dimensions, key positions and alignment interfaces against the figure-based dimensions. Buyers and technical reviewers use it to confirm that rack hardware from different suppliers follows the same 19-inch mechanical interface.
What changed in FprEN IEC 60297-3-103:2026 from the previous edition?
FprEN IEC 60297-3-103:2026 is the second edition and replaces the first edition published in 2004. The foreword says this is a technical revision.
The stated changes are:
- the edition was created based on the technological schemes of the modular 19 in standards series clarified by IEC TR 60297-3-1:2023
- all figures were improved so the interface dimensions and definitions are clearer to users
Which standards are used with FprEN IEC 60297-3-103:2026?
- IEC 60297-3-101 - provides the base dimensions for subracks and associated plug-in units; this part builds on that interface.
- IEC 60297-3-102 - covers the injector/extractor handle and may be used together with this part.
- IEC 60917-1:2019 - provides the generic modular order for mechanical structures and the terms and definitions used here.
- IEC TR 60297-3-1:2023 - is cited in the foreword as the reference that clarified the modular structure scheme used for this revision.
What does the FprEN IEC 60297-3-103:2026 document contain?
The document contains an overview figure of the conventional 19-inch subrack system, then a sequence of interface drawings for keying, alignment and the 2,54 mm offset guide rail arrangement. It includes one inspection table for the subrack and plug-in unit keying chamber dimensions.
It also contains figures showing key dimensions, key programming, chamber inspection, receptacle position and interface inspection dimensions. These are the parts a designer or inspector uses to check whether a plug-in unit can be inserted, aligned and retained correctly in a compatible subrack.
Relations
- Effective Date
- 22-Jul-2025
Frequently Asked Questions
FprEN IEC 60297-3-103:2026 is a draft published by CLC. Its full title is "Mechanical structures for electrical and electronic equipment - Dimensions of mechanical structures of the 482,6 mm (19 in) series - Part 3-103: Keying and alignment pin". This standard covers: Mechanical structures for electrical and electronic equipment - Dimensions of mechanical structures of the 482,6 mm (19 in) series - Part 3-103: Keying and alignment pin
Mechanical structures for electrical and electronic equipment - Dimensions of mechanical structures of the 482,6 mm (19 in) series - Part 3-103: Keying and alignment pin
FprEN IEC 60297-3-103:2026 is classified under the following ICS (International Classification for Standards) categories: 31.240 - Mechanical structures for electronic equipment. The ICS classification helps identify the subject area and facilitates finding related standards.
FprEN IEC 60297-3-103:2026 has the following relationships with other standards: It is inter standard links to EN 60297-3-103:2004. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
FprEN IEC 60297-3-103:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN IEC 60297-3-103:2026
01-januar-2026
Mehanske konstrukcije elektronske opreme - Mere mehanskih konstrukcij v seriji
482,6 mm (19 in) - 3-103. del: Kodirni in poravnalni trn
Mechanical structures for electronic equipment - Dimensions of mechanical structures of
the 482,6 mm (19 in) series - Part 3-103: Keying and alignment pin
Bauweisen für elektronische Einrichtungen - Maße der 482,6-mm-(19-in-)Bauweise - Teil
3-103: Kodierung und Führungsstift
Structures mécaniques pour équipements électroniques - Dimensions des structures
mécaniques de la série 482,6 mm (19 pouces) - Partie 3-103: Codage et broche
d'alignement
Ta slovenski standard je istoveten z: prEN IEC 60297-3-103:2025
ICS:
31.240 Mehanske konstrukcije za Mechanical structures for
elektronsko opremo electronic equipment
oSIST prEN IEC 60297-3-103:2026 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN IEC 60297-3-103:2026
oSIST prEN IEC 60297-3-103:2026
48D/795/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60297-3-103 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-11-14 2026-02-06
SUPERSEDES DOCUMENTS:
48D/791/RR
IEC SC 48D : MECHANICAL STRUCTURES FOR ELECTRICAL AND ELECTRONIC EQUIPMENT
SECRETARIAT: SECRETARY:
Germany Mr Arno Bergmann
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
SC 48B
ASPECTS CONCERNED:
Safety
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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The CENELEC members are invited to vote through the
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the final stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).
TITLE:
Mechanical structures for electronic equipment - Dimensions of mechanical structures of the
482,6 mm (19 in) series - Part 3-103: Keying and alignment pin
PROPOSED STABILITY DATE: 2029
NOTE FROM TC/SC OFFICERS:
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
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oSIST prEN IEC 60297-3-103:2026
IEC 60297-3-103 ED2 © IEC 2025
Link to Committee Draft for Vote (CDV) online document:
https://osd.iec.ch/#/editor/archive/3877bc98-42bb-df99-e063-b912000a38e2/en/CCDV/1
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oSIST prEN IEC 60297-3-103:2026
IEC 60297-3-103 ED2 © IEC 2025
CONTENTS
CONTENTS . 1
FOREWORD . 3
INTRODUCTION . 5
1 Scope and object . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Arrangement overview: Keying of plug-in units in a subrack. 6
4.1 General . 6
4.2 Subrack interface dimensions for keying . 8
4.3 Plug-in unit keying interface dimensions . 8
4.4 Key dimensions . 8
4.5 Programming of keys . 9
4.6 Keying chamber inspection dimensions . 10
5 Arrangement overview: alignment and/or electrical contact of a plug-in unit to a
subrack . 11
5.1 General . 11
5.2 Alignment and/or electrical contact receptacle in the subrack guide rail for
printed board type plug-in units (width dimension ≥ 4 × 5,08 mm) . 12
5.3 Alignment and/or electrical contact interface inspection dimensions . 13
6 Arrangement overview: Subrack guide rail and printed board, 2,54 mm offset of
the printed board reference plane . 13
6.1 General . 13
6.2 Dimensions of the subrack guide rail with 2,54 mm offset of the printed
board reference plane . 15
6.3 Reference plane for printed boards with 2,54 mm offset position . 16
7 Dimensions used in the figures . 16
Bibliography . 17
Figure 1 – Conventional 19-inch subrack system mechanical structure . 5
Figure 2 – Keying of plug-in unit in a subrack . 7
Figure 3 – Subrack interface dimensions for keying . 8
Figure 4 – Plug-in unit keying interface dimensions . 8
Figure 5 – Key dimensions . 9
Figure 6 – Programming of keys . 10
Figure 7 – Front and/or rear subrack and plug-in unit keying chamber inspection
dimensions . 10
Figure 8 – Alignment and/or electrical contact of a plug-in unit to a subrack . 11
Figure 9 – Alignment and/or electrical contact receptacle position in the subrack . 12
Figure 10 – Alignment and/or electrical contact interface inspection dimensions . 13
Figure 11 – Subrack guide rail and printed board, 2,54 mm offset of the printed board
reference plane . 14
Figure 12 – Dimensions of the subrack guide rail with 2,54 mm offset of the printed
board reference plane . 15
Figure 13 – Reference plane for printed boards with 2,54 mm offset position . 16
oSIST prEN IEC 60297-3-103:2026
IEC 60297-3-103 ED2 © IEC 2025
Table 1 – Subrack and plug-in unit keying chamber inspection dimensions . 10
oSIST prEN IEC 60297-3-103:2026
IEC 60297-3-103 ED2 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Mechanical structures for electronic equipment - Dimensions of
mechanical structures of the 482,6 mm (19 in) series -
Part 3-103: Keying and alignment pin
FOREWORD
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