Non-incendive components in Class 1 Div.2

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alte

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I wonder if non-incendive circuits require a separation from all other circuits in Div.2 area. Intrinsicaly safe circuits must be in a separate raceway. What about non-incendive? Have a bunch of pressure transmitters that are approved per UL1604 (non-incendive)- wonder how many conduits to run - mix them with the rest of signals or in a separate raceway.
 

rbalex

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Re: Non-incendive components in Class 1 Div.2

What you are describing is nonincendive field wiring:

501.4(B)(3) Nonincendive Field Wiring. Nonincendive field wiring shall be permitted using any of the wiring methods permitted for unclassified locations. Nonincendive field wiring systems shall be installed in accordance with the control drawing(s). Simple apparatus, not shown on the control drawing, shall be permitted in a nonincendive field wiring circuit, provided the simple apparatus does not interconnect the nonincendive field wiring circuit to any other circuit.
FPN: Simple apparatus is defined in 504.2.
Separate nonincendive field wiring circuits shall be installed in accordance with one of the following:
(1) In separate cables
(2) In multiconductor cables where the conductors of each circuit are within a grounded metal shield
(3) In multiconductor cables, where the conductors of each circuit have insulation with a minimum thickness of 0.25 mm (0.01 in.)
The essential element is: Nonincendive field wiring systems shall be installed in accordance with the control drawing(s).?
500.2 Control Drawing. A drawing or other document provided by the manufacturer of the intrinsically safe or associated apparatus, or of the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus, that details the allowed interconnections between the intrinsically safe and associated apparatus or between the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus.
The control drawing will generally specify the necessary separation of nonincendive circuits from ?common? light and power circuits because they are usually power-limited circuits similar to those specified in Art 725.
 

petersonra

Senior Member
Location
Northern illinois
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engineer
Re: Non-incendive components in Class 1 Div.2

Bob - when did all this stuff get added to the code?

As a practical matter, does it really change anything?
 

rbalex

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Location
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Re: Non-incendive components in Class 1 Div.2

It was "officially" introduced in the 2002 Code.

Part of coordinating Divisions and Zones required updating a lot of product standards. The ISA is the US organization dealing with coordinating with the IEC for "Protection Techniques" (Section 500.7) since they represent a broad range of interests, especially manufacturers. (They are classified as a "Manufactures" on the CMP)

Many of the concepts were in place before, like the wiring was often Art 725 installations and then modified to adapt to Classified locations.

As a practical matter, Section 500.4 "documentation" is an OHSA enforcable item and the "Control Drawings" are part of it.
 

alte

Member
Re: Non-incendive components in Class 1 Div.2

Bob,
In my case there is no control drawing available. The second part of 501.4(B)(3) calls for "separate non-incendive wiring" to be installed in cables. It really contradicts the first part when any wiring method is allowed, unless in my understanding "separate" is required by the control drawing. On the same note if I have a simple apparatus (i.e. thermocouple) - it is permitted as non-incendive wiring and can be wired using any method permitted in unclassified location and installed together with the rest of 24VDC regular circuits in single conduit.

And by the separate conduit I meant separate non-incendive circuits only (apart from 24VDC low voltage DC circuits). Power and light are obviously in their respective conduits.

The canadian electrical code specifically calls for a separate raceway for non-incendive field wiring only. It seems this is not required in NEC.

Mike
 

rbalex

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Location
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Occupation
Professional Electrical Engineer
Re: Non-incendive components in Class 1 Div.2

You are leaving me with a big problem here.

The lack of a control drawing means you have to treat the installation as Art 725 circuits which specifies separation. That assumes that the transmitters are indeed Class 2 or 3 power-limited supplies; otherwise, they would be ?ordinary? power installations and separation is simply a design issue with regard to signal conditioning.

Note: the second part of 501.4(B)(3) does NOT call for ?separate nonincendive wiring" to be installed ..., but that ?separate nonincendive field wiring circuits .? The intent is to avoid interconnection between the circuits that may increase the available ignition energy.
 
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