TIA TIA-4950

This standard applies to:

a) Apparatus or parts of apparatus in Class I, II, or III,Division 1 locations.

Note: Section 500-8(B)(2) of NationalElectrical Code, ANSI/NFPA 70, states that equipment that has beenapproved for a Division 1 location shall be permitted in a Division2 location of the same class and group.

b) Those parts of apparatus located outside of the Class I, II,or III, Division 1 location having a design and construction thatmay influence the intrinsic safety of an electrical circuit withinthe Class I, II, or III, Division 1 location;

c) Apparatus or parts of apparatus in Class I, Zone 0 or 1,Groups IIA, IIB, and IIC locations;

d) Those parts of apparatus located outside of the Class I, Zone0 and 1, Groups IIA, IIB, or IIC location having a design andconstruction that may influence the intrinsic safety of anelectrical circuit within the Class I, Zone 0 and 1, Group IIA,IIB, or IIC location.

These requirements are based on consideration of ignition inlocations made hazardous by the presence of flammable orcombustible material under normal atmospheric conditions.

For the purposes of this standard, normal atmospheric conditionsare considered to be:

• An ambient temperature of 40°C (104°F);
• An oxygen concentration not greater than 21 percent; and
• A pressure of one atmosphere.

This standard does not cover mechanisms of ignition fromexternal sources, such as static electricity or lightning, whichare not related to the electrical characteristics of the apparatus.This standard does not cover apparatus based on high voltageelectrostatic principles, such as electrostatic paint sprayingapparatus.

Purpose

The purpose of this standard is to provide requirements for theconstruction and testing of electrical apparatus, or parts of suchapparatus, having circuits that are not capable of causing ignitionin Division 1 hazardous locations as defined in Article 500.5 ofthe National Electrical Code, ANSI/NFPA 70 – 1987.

This standard is not to be considered an instruction manual foruntrained persons. It is intended to promote uniformity of practiceamong those skilled in the field of intrinsic safety.

Edition:

12

Published:

07/01/2012

Number of Pages:

82

File Size:

1 file , 4.3 MB