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Thread: 24 VDC POWER IN JUNCTION BOX WITH SIGNALS IN C1/D2 NI AREA

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    24 VDC POWER IN JUNCTION BOX WITH SIGNALS IN C1/D2 NI AREA

    I am installing an Ultrasonic Flowmeter that is 24 VDC powered 4 wire passive hart signal in a C1/D2 NI design area. The Flowmeter requires >15 watts 20 to 32 VDC power. The signal is passive 4-20 mA HART powered from our DCS. Can I run the 24VDC power in the same Junction box as the DCS signal? If yes does the instrument and/or the junction box have to be purged? What are the electrical limits of C1/D2 Non Incendive? Volts, Amps,? I have always designed either Explosion Proof or I.S. with barriers so this is still new to me. Thanks

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    I no longer have access to ANSI/ISA-12.12.1; however, nonincendive systems place limits on voltage, current, thermal effects and overall Minimum Ignition Energy (MIE).
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2017 NEC unless otherwise noted.

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