Non incendive for dummies

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Senior Member
I thought I knew what a non-incendive circuit was, but we have a new engineer at that is saying we need barriers on all of our instrument loops. Looking for a good web site or some guidance here as to what non-incedive is.

With the above said, if I have a instrument that is rated for use in a class 1 div2 and my DCS is current limited to 25 ma .. I say no barrier is needed?


Staff member
Mission Viejo, CA
Professional Electrical Engineer
No barriers shown on the dwg.
I suspect you don't have a manufacturer's control drawing. However, if you did, I also suspect it wouldn't show barriers either unless you are trying to use a wiring method not recognized in Section 501.10(B). In Class I, Division 2, you have a pretty broad range of suitable wiring methods including nonincendive; however, nonincendive specifically requires a control drawing [501.10(B)(3)].
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