ASME Y14.44-2008: Reference Designations for Electrical and Electronics Parts and Equipment: Engineering Drawing and Related Documentation Practices

This Standard covers the formation and application of reference designations for electrical and electronics parts and equipment. The reference designations of this Standard are intended for uniquely identifying and locating discrete items on diagrams and in a set; for correlating items in a set; graphic symbols on diagrams; and items in parts lists, circuit descriptions, and instructions. This Standard includes three methods for forming and applying reference designations. (a) the unit numbering method (b) the location numbering method (c) the location coding method A complete reference designation may incorporate reference designations formed by the use of any of these methods at any level from basic parts to complete units. The unit numbering method has a long history of satisfactory use in all types of electrical and electronics equipment. The location numbering method and location coding method have been developed to permit a rapid physical location of items in large, complicated equipment featuring multiple use of many identical or closely similar items. These methods shall be applied in such a way that duplicate complete reference designations do not occur in a piece of equipment or system. Device function designations for power switchgear and industrial control use are not covered by this Standard. CONTENTS 5 COMMITTEE ROSTER 5 FOREWORD 6 CORRESPONDENCE WITH THE Y14 COMMITTEE 8 1 GENERAL 9 1.1 Scope 9 1.2 Application 9 1.3 References to This Standard 9 1.4 Changes in Reference Designation Class Letters 9 1.5 Use of "Shall," "Should," and "May" 9 1.6 Reference 9 1.7 Definitions 10 2 UNIT NUMBERING METHOD 11 2.1 Basic Reference Designations 11 2.1.1 Class Letter. 11 2.1.1.1 Special Class Letter Considerations. 11 2.1.2 Number. 11 2.1.3 Sequential Number Assignment. 11 2.1.4 Suffix Letter. 11 2.1.5 Special Cases 11 2.1.5.1 Terminals. 11 2.1.5.2 Sockets 12 2.1.5.2.1 Single-Item Mounting. 12 2.1.5.2.2 Multiple-Item Mounting. 12 2.1.5.3 Connectors. 12 2.1.5.4 Supplementary Information. 14 2.1.5.5 Intersubassembly and Interunit Cable Connections. 14 2.1.5.6 Repeated-Use Circuits. 15 2.1.5.7 Selected and Matched Parts. 15 2.1.6 Reference Designations for Relays 15 2.1.6.1 Class Letter. 15 2.1.6.2 Elements of Relays. 15 2.1.7 Reference Designations for Switches 16 2.1.7.1 Class Letter. 16 2.1.7.2 Elements of Switches. 16 2.1.8 Actual Versus Intended Function. 16 2.2 Complete Reference Designations 16 2.2.1 Systems, Sets, and Groups. 16 2.2.2 Units of a Set. 16 2.2.2.1 Units of a Group. 16 2.2.2.2 Units Not Part of a Set. 16 2.2.3 Identification of Items in a Unit Which Are Not in a Subassembly. 1 16 2.2.4 Identification of Items of Subassemblies. 18 2.2.5 Expansion of Method. 18 2.2.6 Subassemblies and Parts Not Integral With Units. 18 2.2.7 Partial Reference Designations. 18 2.2.8 Special Cases 18 2.2.8.1 Identical Units. 18 2.2.8.2 Identical Assemblies and Subassemblies. 18 2.2.8.3 Inseparable Subassemblies, Modular Assemblies, Printed Circuit Boards, and Integrated Circuit Packages. 19 3 LOCATION NUMBERING METHOD 19 3.1 General 19 3.2 Sequential Numbering 19 3.3 Coordinate Numbering 19 3.3.1 Coordinate Increments. 19 3.3.2 Coordinate Numbers. 19 3.4 Number Assignment 20 3.5 Area Identification 20 3.6 Location Assignment Drawings 21 3.7 Intermixing of Numbering Methods 21 3.8 Reuse of Numbers of Deleted Parts 21 3.9 Marking on Equipment 21 4 LOCATION CODING METHOD 21 4.1 General 21 4.2 Sequential Coding 21 4.3 Coordinate Coding 22 4.3.1 Coordinate Increments. 22 4.3.2 Coordinate Codes. 22 4.3.3 Number and Letter Assignment. 22 4.4 Additional Rules 23 4.5 Area Identification 23 4.6 Location Drawing 23 4.7 Intermixing of Methods 23 4.8 Reuse of Locations 23 4.9 Partial Location Codes 23 4.10 Connectors and Sockets 23 4.11 Levels With Adjacent Letters or Numbers 23 4.12 Rows and Columns 23 4.13 Marking on Equipment 25 5 DESIGNATION OF DEPOSITED COMPONENTS ON HYBRID PRINTED CIRCUITS 25 6 MARKING ON EQUIPMENT 25 6.1 Marking Requirements for Reference Designations 25 6.2 Location of Markings 25 6.2.1 Enclosed Parts. 26 6.2.2 Plug-In Subassemblies and Parts, Mounting Sockets, and Connectors. 26 6.2.3 Cable Assemblies. 26 6.3 Partial Reference Designations 26 6.4 Multiple-Use Assemblies 27 6.5 Functional Designations 27 7 CLASS DESIGNATION LETTERS 27 FIGURES 5 1 Typical Basic Reference Designations in a Diagram 11 2 Socket Reference Designations and Markings 12 3 Reference Designation in a Typical Schematic Diagram 13 4 Connector Designations for Plug-In Items 14 5 Typical Connector and Interunit Cable Designation 15 6 Physical and Circuit Relationship of N-Designated Circuit Groups 15 7 Typical System Subdivision 17 8 A Typical Set 17 9 Identification of Subassemblies and Parts of Units 18 10 Identification of Items of Subassemblies 19 11 Application of Reference Designations to a Unit 19 12 Intermixture of Unit Numbering Method and Location Numbering Method in the Same Unit 20 13 Typical First-Level Coordinate Number Assignment 20 14 Use of Suffix Letter to Locate Surfaces 21 15 Location Numbering Applied at Several Subdivision Levels 22 16 Coordinate First-Level Breakdown 23 17 Sequential-Type, First-Level Breakdown 24 18 Location Coding of Multiple Levels of Equipment 24 19 Coding of Panels 25 20 Identifiable Rows and Columns 25 21 Designation of Deposited Components on Hybrid Printed Circuits 26 NONMANDATORY APPENDIX 29 A BLOCK NUMBERING METHOD 29 FIGURES......Page 5 FOREWORD......Page 6 CORRESPONDENCE WITH THE Y14 COMMITTEE......Page 8 1.6 Reference......Page 9 1.7 Definitions......Page 10 1 Typical Basic Reference Designations in a Diagram......Page 11 2 Socket Reference Designations and Markings......Page 12 4 Connector Designations for Plug-In Items......Page 14 6 Physical and Circuit Relationship of N-Designated Circuit Groups......Page 15 2.2.3 Identification of Items in a Unit Which Are Not in a Subassembly. 1......Page 16 9 Identification of Subassemblies and Parts of Units......Page 18 11 Application of Reference Designations to a Unit......Page 19 13 Typical First-Level Coordinate Number Assignment......Page 20 14 Use of Suffix Letter to Locate Surfaces......Page 21 15 Location Numbering Applied at Several Subdivision Levels......Page 22 16 Coordinate First-Level Breakdown......Page 23 20 Identifiable Rows and Columns......Page 25 21 Designation of Deposited Components on Hybrid Printed Circuits......Page 26 7 CLASS DESIGNATION LETTERS......Page 27 3 Reference Designation in a Typical Schematic Diagram......Page 13 8 A Typical Set......Page 17 18 Location Coding of Multiple Levels of Equipment......Page 24 A BLOCK NUMBERING METHOD......Page 29