D. McKinnon, ast technology Labs, Inc. (To be ansi/tia-571-B) Telecommunications Telephone Terminal Equipment Environmental Considerations

1.INTRODUCTION

1. 
   This standard is one of a series of technical standards on telecommunications user premises equipment (hereinafter referred to as “equipment” or “terminal equipment”), prepared by TIA Engineering Committee TR-41. This document, along with its companion standards, fills a recognized need in the telecommunications industry brought about by the use of user premises equipment sup-plied by numerous different manufacturers. It will be useful to anyone engaged in the manufacture of user premises equipment and to those purchasing, operating or using such equipment or devices.
   
2. 
   The standard establishes performance and technical criteria for interfacing and connecting with the various elements of the public telephone network. Compliance with these requirements should assure quality service. In some cases, quality performance requires the inclusion of location-oriented options in the equipment. This flexibility is needed to accommodate differences in operating environment between telephone companies and in a few cases, significant differences between network switching systems. Therefore, in order to assure satisfactory performance, two items are needed: equipment design compliance and a process for configuring the terminal equipment to the requirements of its serving area.
   
3. 
   In accordance with EIA Engineering Publication EP-7, two categories of performance standards are specified: mandatory and advisory. The mandatory performance criteria are designated by the word "shall"; advisory criteria are designated by the words "should," "may," or "desirable" (which are used interchangeably in this standard). The mandatory criteria generally apply to safety and protection, signaling and compatibility. They specify the absolute minimum acceptable performance levels in areas such as transmission parameters, equipment parameters, and durability.
   
4. 
   Advisory or desirable criteria represent product goals. In some instances, these criteria are included in an effort to assure universal product compatibility, even with equipment and facilities operational in statistically small quantities. In some cases, advisory criteria are presented when their attainment will enhance the general performance of the product in all its contemplated applications. Where both a mandatory and an advisory level are specified for the same criterion, the advisory level represents a goal currently identifiable as having distinct compatibility advantages, performance advantages, or both, toward which future designs should strive.
   
5. 
   As technology and application engineering techniques advance, the criteria contained in this document will become subject to change.
   
6. 
   Some of the tests prescribed in this standard may involve the presence of hazardous voltages and currents or other potential dangers to test personnel. Some of these hazards have been identified, and appropriate warnings have been included in the text prescribing such tests. However, appropriate safety precautions are always recommended when performing any laboratory test.
   

2.SCOPE

This document establishes environmental conditions which should be addressed in the design of telecommunications user premises equipment for interfacing and connecting with the various elements of the public telephone network. It defines physical and electrical conditions that the equipment may be subject to. This document applies to equipment as described in:

1. 
   TIA-464-B-1996, Private Branch Exchange Switching Equipment (Ref. A1);
   
2. 
   EIA-470-A-1987, Telephone Instruments (Ref. A2);
   
3. 
   TIA-547-1989, Network Channel Terminal Equipment (Ref. A3);
   

and such other standards which TIA Engineering committee TR 41 may promulgate.

This document describes environmental conditions applicable to equipment , and reflects engineering judgment for the telecommunications industry in the United States and Canada. The conditions are based on present telecommunications plant characteristics at the equipment interface. The requirements contained in this document should ensure satisfactory user voice service in a high percentage of installations both initially and over some period of time as the network grows and changes occur in telephone serving equipment.

3.DEFINITIONS

3.1.Earth (Ground)

A remote location considered to be at zero potential. Used interchangeably with “ground.”

3.2.Exposed Surfaces

Surfaces of equipment that may be contacted with the test probe defined in UL 1950 (figure 16).

3.3.Grounding Conductor

The conductor connecting the equipment’s frame or grounding terminal to a building’s ground system.

3.4.Network Interface or Demarcation Point

The point of interconnection between telephone company communications facilities and terminal equipment, protective apparatus or wiring at a subscriber's premises. The network interface or demarcation point is located on the subscriber’s side of the telephone company's protector, or the equivalent thereof in cases where a protector is not employed, as provided under the local telephone company’s reasonable and nondiscriminatory standard operating practices. See also Ref. A4.

3.5.Normal Operation

Normal operation occurs when the equipment meets all the requirements given in the appropriate EIA or EIA/TIA equipment standards. Normal operation includes random execution of functions representative of those for which the equipment is designed. For equipment intended for simultaneous operation of multiple functions, such as a PBX, normal operation includes random operation of a significant portion of those functions but not necessarily at the maximum rated capacity.

3.6.Outside Plant Interface Leads (OP)

These are CO-PBX trunk, tie trunk, ACD, off-premises station and other interface leads that connect to out-of-building facilities. They include, but are not limited to, telecommunications pairs that connect to the network interface. The interface leads are shown in figure 1.

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