Non Incendive wiring method

[TomzH]

I'm new at Mike Holt's forum. It's a really good forum to have great information. My name is Tommy and I'm working as an instrumentation engineer in Canada. We are currently working on a project for the USA, where the electrical installation is covered by NEC 2011.


I'm looking to power some equipment certified for Class I, Div 2 NI. (The control drawing is in attachment)


Firstly, in the NEC 2011, article 501.10 (B) (3) say that you can use NonIncendive Field Wiring method. However, the NonIncendive wiring method is not clearly explain in the NEC and how to do the wiring correctly. Is it possible to have some clear exemples (with specification of all components in ths exemple, like certifications, manufacturer, etc.) or basic concepts about the Nonincendive method? Is it possible to have a book for that?


Secondly, If I use the Nonincendive wiring method, how I power my equipment? To meet the Nonincendive requirements, which kind of power supply is required, is it obligatory to dedicate this power supply for the Nonincendive equipment or I can power any other unclassified equipment in my control panel (panel is in the unclassified area)?

The intrinsically safe wiring method is very clear with the use of an intrinsic barrier. The Nonincendive method is not as clear as intrinsically safe system.


Is it possible to have some clarification about my questions.


Best Regards,
Tommy

 

[rbalex]

You might review the various nonincendive related definitions, especially nonincendive circuit in Section 500.2 and the ANSI/ISA reference document mentioned in the FPN/INs.

 

[TomzH]

I can read all definitions, but the definitions are very large. The are no concrete exemple.


Also, with the datasheet of the Endress&Hauser pressure transmitter, can you give me an exemple to how to connect this equipment to respect the Class I div 2 requirements of the control drawing. I just want to have an exemple of the power supply to use (manufacturer & part number) and how to connect the 4-20mA signal to analog input card, SIEMENS #6ES7 331-7KF02-0AB0. To be Nonincendive, do I need an interface module between the 4-20mA signal of the transmitter to the plc analog input module? What is the restrictions to connect my Nonincendive wires to the terminal of the analog input card, where the other inputs are not Nonincendive?


I know that we need more precautions to meet the class I Div 2 requirements, for example the seal at the boundary, the type of cable, wire duct dedicate to the Non incendive circuits, etc. But I would like to have an example of a general case to help my understanding of the NonIncendive wiring method of the NEC2011.

Best Regards,
Tommy