NEC Article 725: requirement or loophole

Author

Durham, Marcus O. ; Lockerd, Clark R.

Author_Institution

Theway Corp., Tulsa, OK, USA

fYear

1988

fDate

12-14 Sep 1988

Firstpage

15

Lastpage

19

Abstract

It is argued that Article 725 is one of the less obvious but powerful sections of the National Electrical Code. This article covers remote-control, signaling, and power-limited circuits that are not an integral part of a device or appliance. The limitations imposed and the advantages provided by the section are discussed. Application in conjunction with hazardous environments is presented. The installation, application, and transient protection of communications cable for instrumentation circuits is outlined. It is concluded that use of power-limited circuits with intrinsically safe equipment significantly reduces the complexity and cost associated with hazardous environments and inexpensive communication cable can be used for power-limited controls. Direct burial cable makes possible excellent performance and wide bandwidth. Lightning and transient protection can be very effectively implemented. Installation is simple and reliable

Keywords

health hazards; power integrated circuits; signalling; standards; telecontrol; NEC Article 725; National Electrical Code; hazardous environments; lightning protection; power-limited circuits; remote-control; signaling; transient protection; Bandwidth; Circuits; Communication cables; Communication system control; Costs; Home appliances; Instruments; Lightning; National electric code; Protection;

fLanguage

English

Publisher

ieee

Conference_Titel

Petroleum and Chemical Industry Conference, 1988, Record of Conference Papers., Industrial Applications Society 35th Annual

Conference_Location

Dallas, TX

Type

conf

DOI

10.1109/PCICON.1988.22412

Filename

22412