IEC 60297-3-105:2008

IEC 60297-3-105
Edition 1.0 2008-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Mechanical structures for electronic equipment – Dimensions of mechanical
structures of the 482,6 mm (19 in) series –
Part 3-105: Dimensions and design aspects for 1U high chassis

Structures mécaniques pour équipements électroniques – Dimensions des
structures mécaniques de la série 482,6 mm (19 pouces) –
Partie 3-105: Dimensions et aspects de conception pour les châssis d’une
hauteur de 1U
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IEC 60297-3-105
Edition 1.0 2008-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Mechanical structures for electronic equipment – Dimensions of mechanical
structures of the 482,6 mm (19 in) series –
Part 3-105: Dimensions and design aspects for 1U high chassis

Structures mécaniques pour équipements électroniques – Dimensions des
structures mécaniques de la série 482,6 mm (19 pouces) –
Partie 3-105: Dimensions et aspects de conception pour les châssis d’une
hauteur de 1U
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
Q
CODE PRIX
ICS 31.240 ISBN 978-2-88910-096-5
– 2 – 60297-3-105 © IEC:2008
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Normative references .6
3 Terms and definitions .6
4 Arrangement overview.7
5 Dimensions of the 1U chassis.9
5.1 Chassis type A .9
5.2 Chassis type B .10
5.3 Chassis type C .11
6 Climatic, mechanical tests (safety aspects, EMC, seismic) .12
Annex A (informative) Chassis and rack/cabinet relationship .13
Annex B (informative) Cooling air flow .15
Annex C (informative) Chassis depth relationship to the rack/cabinet .16

Figure 1 – Chassis type A.8
Figure 2 – Chassis type B.8
Figure 3 – Chassis type C.8
Figure 4 – Dimensions of chassis type A.9
Figure 5 – Dimensions of chassis type B.10
Figure 6 – Dimensions of chassis type C .11
Figure A.1 – Chassis type B and rack/cabinet relationship .13
Figure A.2 – Chassis type C rack/cabinet relationship.14
Figure B.1 – Cooling airflow direction.15

Table C.1 – Maximum depth D in relation to corresponding cabinet depth.16

60297-3-105 © IEC:2008 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
______________
MECHANICAL STRUCTURES FOR ELECTRONIC EQUIPMENT –
DIMENSIONS OF MECHANICAL STRUCTURES
OF THE 482,6 mm (19 in) SERIES –

Part 3-105: Dimensions and design aspects for 1U high chassis

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
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agreement between the two organizations.
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indispensable for the correct application of this publication.
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60297-3-105 has been prepared by subcommittee 48D:
Mechanical structures for electronic equipment, of IEC technical committee 48:
Electromechanical components and mechanical structures for electronic equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
48D/381/FDIS 48D/387/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 60297-3-105 © IEC:2008
A list of all parts of IEC 60297 series, published under the general title Mechanical structures
for electronic equipment – Dimensions of mechanical structures of the 482,6 mm (19 in)
series, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
60297-3-105 © IEC:2008 – 5 –
INTRODUCTION
Electronic systems based on 1U chassis design have become one of the most important
platforms used for servers, industrial electronics, information technology (IT) and
telecommunication equipment. 1U chassis are sometimes referred to as “Pizza Boxes”.
Applications for 1U chassis designs are wide spread and solutions are found in every
segment of the electronics industry.
IEC 60297-3-100 defines the dimensional rack/cabinet details such as the available aperture
and the front panel mounting dimensions. However, IEC 60297-3-100 falls short of providing
guidance or dimensional requirements for assembling 1U chassis designs into these
IEC 60297 conforming racks/cabinets either in singles or in multiples (stacked in n × 1U).
This part of IEC 60297 will give guidance and provide for dimensional requirements for 1U
chassis based on weight loading, physical size and service accessibility.
In this standard, various chassis types are identified according to application needs.
The defined interface dimensions of the various chassis types permit the development of
common mounting accessories. Due to this clarification and the application specific chassis
type choice, the serviceability and airflow aspects of the chosen 1U chassis can be addressed
by the designer.
Similar attributes for multiple unit high equipment may be derived from this standard. The
economical value of this standard lies in the predefined interface dimensions of chassis for
which suitable accessories may be developed. In addition, as a consequence of the chosen
mounting support, the cooling possibilities are indicated.

– 6 – 60297-3-105 © IEC:2008
MECHANICAL STRUCTURES FOR ELECTRONIC EQUIPMENT –
DIMENSIONS OF MECHANICAL STRUCTURES
OF THE 482,6 mm (19 in) SERIES –

Part 3-105: Dimensions and design aspects for 1U high chassis

1 Scope
This part of IEC 60297 specifies the dimensions for 1U chassis mounted into IEC 60297-3-
100 compliant racks/cabinets where dimensions, loaded weight and accessibility require
differing assembly methods.
Guidance for cooling and reference for EMC, seismic and for the climatic and mechanical
requirements and tests are provided, as defined in the IEC 61587 series.
The drawings used in this standard are not intended to indicate product design, only the
specific dimensions shall be used.
The terminology used complies with IEC 60917-1.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60050-581, International electrotechnical vocabulary – Part 581: Electromechanical
components for electronic equipment
IEC 60917-1, Modular order for the development of mechanical structures for electronic
equipment practices – Part 1: Generic standard
IEC 60297-3-100, Mechanical structures for electronic equipment – Dimensions of mechanical
structures of the 482,6 mm (19 in) series – Part 3-100: Basic dimensions of front panels,
subracks, chassis, racks and cabinets
IEC 61587-1, Mechanical structures for electronic equipment – Tests for IEC 60917 and
IEC 60297 – Part 1: Climatic, mechanical tests and safety aspects for cabinets, racks,
subracks and chassis
IEC 61587-2, Mechanical structures for electronic equipment – Tests for IEC 60917 and
IEC 60297 – Part 2: Seismic tests for cabinets and racks
IEC 61587-3, Mechanical structures for electronic equipment – Tests for IEC 60917 and
IEC 60297 – Part 3: Electromagnetic shielding performance tests for cabinets, racks and
subracks
3 Terms and definitions
For the purposes of this document, the terms and definitions of IEC 60917-1 and IEC 60050-
581 apply, as well as the following.

60297-3-105 © IEC:2008 – 7 –
3.1
19 in cabinet
cabinet in accordance with IEC 60297-3-100
3.2
19 in vertical members
parts of a cabinet with the mounting holes for front panels, chassis and subracks
3.3
chassis slides
angled parts mounted in the cabinet to support heavy or deep chassis (see also IEC 60917-1)
3.4
telescopic slide
extendable mounting support for heavy or deep chassis within a cabinet, providing easy
access to rear parts in extended position of the chassis
3.5
aperture of a cabinet
horizontal opening dimension between two 19 in uprights
3.6
height pitch line
theoretical line between any increment of U (1U = 44,45 mm)
3.7
cable management
cable routing within a cabinet to the equipment
3.8
chassis mounting flanges
may be an integrated part of the chassis or separate brackets attached to the chassis
3.9
cable pull factor
summary of cable weight, linked to the chassis
4 Arrangement overview
The arrangement overview in Figure 1 illustrates the chassis mounting methods into a typical
19 in cabinet.
The 1U chassis dimensions differ pending on the choice of the chassis type and resulting
mounting dimensions. There are three types of chassis, determined by the principal methods
of mounting into a cabinet. The definitions of the three types of chassis are:
● Chassis type A: This type of chassis is mounted into racks/cabinets without chassis
supports (light weight, shallow equipment with low cable pull factor, IEC 61587-1 DL 1
shock/vibration environment). For the assembly into cabinets only, the chassis mounting
flanges are bolted to the 19 in uprights. This type of chassis provides the maximum use of the
available width and heights within a 1U section. See Figure 1.
● Chassis type B: This type of chassis is designated for equipment with higher load (high
rear cabling pull factor, IEC 61587-1 DL 1 shock/vibration environment). Therefore, chassis
slides shall be used. The chassis design shall provide recessed areas as a space for the
cabinet mounted chassis slides. See Figure 2.

– 8 – 60297-3-105 © IEC:2008
● Chassis type C: This type of chassis is designated for extendable equipment mounted on
telescopic slides (top cover and/or rear I/O access via rear cable management, IEC 61587-1
DL 1 environment). Telescopic slides may be of two or three parts, dependent on the
extension requirement. The chassis design shall provide on both sides recessed areas
dependent on the required space for the telescopic slides.
NOTE There is no standard for telescopic slides, mounting dimensions should be defined by the equipment
design. See Figure 3.
19 in vertical member
1U chassis
IEC  2064/08
Figure 1 – Chassis type A
19 in vertical member
Chassis slide
IEC  2065/08
1U chassis
Figure 2 – Chassis type B
19 in vertical member
Telescopic slide
1U chassis IEC  2066/08
Figure 3 – Chassis type C
60297-3-105 © IEC:2008 – 9 –
5 Dimensions of the 1U chassis
IEC 60297-3-100 defines the front panel dimensions and the aperture of the rack/cabinet.
5.1 Chassis type A
This type of chassis is typically of either light weight, limited depth and/or has a very low
cable pull factor. Therefore, the centre of gravity is relatively close to the chassis front panel
where the chassis mounting screws to the rack/cabinet uprights are located. Figure 4
illustrates the recommended chassis dimensions utilizing the maximum available cabinet
aperture dimension for a 1U chassis. The maximum cable pull factor is to be considered in
addition to the maximum weight. The mounted chassis vertical deflection shall not pass over
the theoretical rack/cabinet height pitch line.
The maximum width as shown in Figure 4 includes any attached mounting flanges as well as
mounting screws.
Front view
Hole dimensions (see IEC 60297-3-100)
13,5 ± 0,4
465,1 ± 1,6
Height pitch line
482,6 ± 0,4 (19 in)
Top view
≤ 449
Missing dimensions
(see IEC 60297-3-100)
IEC  2067/08
Dimensions in millimetres
Figure 4 – Dimensions of chassis type A
31,75 ± 0,4
5,9 ± 0,4
D
43,65 ± 0,4
44,45
– 10 – 60297-3-105 © IEC:2008
5.2 Chassis type B
For the type B chassis as shown in Figure 5 the chassis height dimension shall be reduced in
order to provide for chassis support space. For the purposes of this standard, the chassis
height is reduced by 2 mm at the bottom of the chassis height. This provides for an
interference free modular mounting approach of multiple and/or different chassis or subracks
in a rack/cabinet.
Where maximum available chassis height is required, only the chassis to mounting support
interfaces have to be observed.
For safety reasons and for the load bearing calculation of the chassis slides, the total weight
shall not exceed 25 kg.
Side view Rear view
1)
≤ 10
≤ 350
Height pitch line
Recessed area for corresponding chassis slides

1)
The dotted line indicates that the recess may be throughout the whole width
Top view
≤ 449
Missing dimensions
(see IEC 60297-3-100)
IEC  2068/08
Dimensions in millimetres
Figure 5 – Dimensions of chassis type B
43,65 ± 0,4
≥ 2, 0
D
60297-3-105 © IEC:2008 – 11 –
5.3 Chassis type C
For the type C chassis as shown in Figure 6, the chassis width dimension is reduced to
provide space for single, double or triple extension telescopic slides.
The type C chassis may require cable management between the rear of the chassis and the
rack/cabinet interface.
The type C chassis dimensions are based on the triple extension telescopic design and the
telescopic slides are within the 1U chassis dimension.
The type C chassis load, when fully extended out of the rack/cabinet, must be observed in
means of the possible dangerous tilt effect of a free standing rack/cabinet. The recommended
chassis width of maximum 425 mm leaves 2 × 12 mm space for the extendable parts of the
telescopic slides (see Clause A.2). There is no standard for telescopic slides, but the
recommended dimension of 12 mm complies with the most common products in the
electronics market and in relation to the maximum load.
NOTE For safety reasons (tilt effect of a cabinet by fully extended chassis) and for the load bearing calculation of
telescopic slides the chassis shall not exceed 25 kg.

1)
Side view
≤ 10
2)
1) Height pitch line
Keep out area for telescopic slides
2)
Mounting holes to be defined dependent on telescopic slide chosen
≤ 449
Top view
≤ 425
Missing dimensions
(see IEC 60297-3-100)
IEC  2069/08
Dimensions in millimetres
Figure 6 – Dimensions of chassis type C
43,65 ± 0,4
D
– 12 – 60297-3-105 © IEC:2008
6 Climatic, mechanical tests (safety aspects, EMC, seismic)
For the test of mechanical integrity, dedicated tests are described in the IEC 61587 series.
This standard should be referenced in technical specifications as a common base for the
design properties of 1U equipment. The 1U chassis are not explicitly described in the above
mentioned standard. Therefore, the tests for the chassis should be performed according to
the subracks.
60297-3-105 © IEC:2008 – 13 –
Annex A
(informative)
Chassis and rack/cabinet relationship

A.1 Chassis type B and rack/cabinet relationship

Top view
Cross section
Rack/cabinet aperture between
Chassis mounted on slides
Rack/cabinet envelope dimensions the 19 in vertical members
in accordance with IEC 60297-3-100 ≥ 450
Mounting dimensions of
the 19 in vertical member
in accordance with
1)
IEC 60297-3-100
Rack/cabinet
mounted slide
≥ 355
≤ 449
1)
Minimum distance of the slide to the 19 in uprights attachment plane
Rear view
(see clause 5.2)
≤ 350
≤ 449
IEC  2070/08
Dimensions in millimetres
Figure A.1 – Chassis type B and rack/cabinet relationship
≥ 15
≥ 2, 0
– 14 – 60297-3-105 © IEC:2008
A.2 Chassis type C rack/cabinet relationship

≥ 450
Usable space for
telescopic slides
Chassis mounted on
(12, 0)
≤ 425 telescopic slides
Mounting dimensions of
the 19 in vertical member
in accordance with
IEC 60297-3-100
1)
Telescopic slide mounted
to the rack/cabinet structure
Rack/cabinet envelope
dimensions
in accordance with
IEC 60297-3-100
1)
Chassis type C top and rear I/O access to be defined by the designer and installer defined cable management
IEC  2071/08
Dimensions in millimetres
Figure A.2 – Chassis type C rack/cabinet relationship

60297-3-105 © IEC:2008 – 15 –
Annex B
(informative)
Cooling air flow
For well-controlled heat management within a cabinet, the air flow through multiple built-in
chassis or subracks should be in the same direction. The preferred air flow direction for 1U
chassis is from front to rear. As an alternative side to side or side to rear air flow may be
considered. These alternative air flow solutions are mainly used for stand-alone equipment.
These rules apply
...