Instrumentation Electrical Requirements. Enclosures for electrical instruments shall comply with requirements of the Electrical Area Classification in which they are installed. If the manufacturer of certain instruments cannot provide enclosures suitable for the area, purging of the enclosure with inert, dry air or gas shall be given consideration. Cases for locally mounted instruments and devices shall be weatherproof as a minimum. Terminals for electrical interconnections including thermocouple wire shall be clearly identified to indicate polarity, electrical ground where applicable, and test connection. Terminals for purchased items shall normally be identified in accordance with manufacturer’s standard marking. Electrical conduit connections for locally mounted instruments shall normally be internally threaded, where available as manufacturer’s standard option. Connections shall be suitable for the Electrical Area Classification in which the instrument is installed.
