Nonincendive circuits

[don_resqcapt19]

The rule as far as required separation of nonincendive circuits from other circuits in 501.10(B)(3) is not really clear to me. I assume the rule is saying that the nonincendive circuits cannot be mixed with other circuits.

Also I assume that the required control diagram should say something about the power supply that is located in the non-classified area. I requested a control diagram and all I received was a terminal block wiring diagram with no other information. I don't think that is a "control diagram" as required by the code.

 

[petersonra]

The rule as far as required separation of nonincendive circuits from other circuits in 501.10(B)(3) is not really clear to me. I assume the rule is saying that the nonincendive circuits cannot be mixed with other circuits.

Also I assume that the required control diagram should say something about the power supply that is located in the non-classified area. I requested a control diagram and all I received was a terminal block wiring diagram with no other information. I don't think that is a "control diagram" as required by the code.

I think the rule is saying that individual NI circuits have to have separation from each other.

the control diagram comes from the manufacturer. it does not have to say "control diagram" on it, as long as it shows how to wire it up. what more do you think is necessary?

I am not sure there are any special requirements for the power supply.

 

[rbalex]

The ISA (currently the International Society of Automation - a name they change regularly) is the US representative to the IEC Committee on Hazardous Atmospheres and have developed a tremendous influence with CMP 14.

That said, I suggest reviewing the definitions of Control Drawing and Nonincendive Circuit ​(especially it's FPN/IN).

This is only my opinion, but I believe nonincendive and intrinsically safe systems are going the way of Art 725 in that the ISA is as much interested in protecting their signals as preventing fires, shocks, etc.

 

[don_resqcapt19]

...
the control diagram comes from the manufacturer. it does not have to say "control diagram" on it, as long as it shows how to wire it up. what more do you think is necessary? ...

This is a valve position indicator and all they gave me is a drawing that shows what terminals are for the closed limit switch and what terminals are for the open limit switch. The device also has LEDs to indicate the valve position if you are looking at the valve in the field. I expect that the control diagram would have to show me a complete circuit if they are saying it is nonincendive. I would expect that the power source or the device that the position indicator is connected to would have a big effect as to the complete circuit being nonincendive.