Intrinsically Safe "BLUE"

[jpayne]

I am seeing more and more information on the WEB in reference to blue terminal blocks representing "Intrinsically Safe."

To me, intrinsically safe means Class 1, Div 1. When I search the NEC handbook (specifically sections 501-4(a)) I can find nothing that designates the color blue as an identifier for this safety specification.

Is this a new specification? Or is this just a common occurrence which people have adopted?

From my past experiences, blue terminal blocks have typically represented 24VDC(+). But again, I know that this is not a standard and if you are dealing with a European built machine you will definitely see a different color representing 24V.

Any information regarding a color code specification for Class1, Div1 or intrinsically safe devices/wiring methods would be greatly appreciated.

 

[rbalex]

Re: Intrinsically Safe "BLUE"

The general rules are 504.80 "Identification" with "light blue" specifically referring to conductors in 504.80(C).

Section 504.80(A)requires terminals to be clearly identified; color coding is always an option.

"Intrinsic Safety" is a protection method recognized as acceptable in Division 1 locations per 500.7(E). It does not necessarily imply a location is so classified. The rest of Art 504 describes the general installation and application requirements unique to intrinsically safe systems.

 

[petersonra]

Re: Intrinsically Safe "BLUE"

Originally posted by jpayne:
I am seeing more and more information on the WEB in reference to blue terminal blocks representing "Intrinsically Safe."

To me, intrinsically safe means Class 1, Div 1. When I search the NEC handbook (specifically sections 501-4(a)) I can find nothing that designates the color blue as an identifier for this safety specification.

Is this a new specification? Or is this just a common occurrence which people have adopted?

From my past experiences, blue terminal blocks have typically represented 24VDC(+). But again, I know that this is not a standard and if you are dealing with a European built machine you will definitely see a different color representing 24V.

Any information regarding a color code specification for Class1, Div1 or intrinsically safe devices/wiring methods would be greatly appreciated.

I doubt the NEC specifies blue as a color for IS cirucits, however it is the most commonly used way to do so. Its common to see blue plastic wire duct to so designate, sometimes conduits containing such circuits are painted blue (or labeled).

IS can be used in both division 1 and 2 areas, but these days is not seen as much in division 2 areas since there are often more cost effective ways to protect against ignition.

[ September 20, 2004, 11:14 AM: Message edited by: petersonra ]

 

[tom baker]

Re: Intrinsically Safe "BLUE"

Section 504.80 (C)requires blue for IS circuits. There is a UL standard for IS control panels it may require blue for the terminal blocks

540.80(B) Wiring. Raceways, cable trays, and other wiring methods for intrinsically safe system wiring shall be identified with permanently affixed labels with the wording ?Intrinsic Safety Wiring? or equivalent. The labels shall be located so as to be visible after installation and placed so that they may be readily traced through the entire length of the installation. Intrinsic safety circuit labels shall appear in every section of the wiring system that is separated by enclosures, walls, partitions, or floors. Spacing between labels shall not be more than 7.5 m (25 ft).
Exception: Circuits run underground shall be permitted to be identified where they become accessible after emergence from the ground.

(C) Color Coding. Color coding shall be permitted to identify intrinsically safe conductors where they are colored light blue and where no other conductors colored light blue are used. Likewise, color coding shall be permitted to identify raceways, cable trays, and junction boxes where they are colored light blue and contain only intrinsically safe wiring.

 

[jpayne]

Re: Intrinsically Safe "BLUE"

Hey ... Thanks for all of the responses! You guys told me exactly what I needed to know (which is that my NEC book is out-dated).

After getting the latest NEC and reviewing the article mentioned, it is clear that nothing is completely clear.

'Light Blue' is definitely the color mentioned. But, this does not have the required sense of a "Green" Ground terminal block.

This seems to be more of a suggestion.
504.80 (C) "Color coding SHALL BE PERMITTED to identify intrinsically safe conductors ..."

504.80 (B) has more of a required sense to it.
"Raceways, cable trays & other wiring methods for intrinsically safe system wiring SHALL BE IDENTIFIED w/ permanently affixed labels ..."

I broke down and called Alex our HazLoc Project Engineer @ UL and he summarized this as a good recommendation if you intend to color code ... but not a standard nor a requirement.

Thanks to each of you for your contribution.

Best Regards,
Jeff

 

[petersonra]

Re: Intrinsically Safe "BLUE"

Originally posted by tom baker:
Section 504.80 (C)requires blue for IS circuits. There is a UL standard for IS control panels it may require blue for the terminal blocks

<snip>

(C) Color Coding. Color coding shall be permitted to identify intrinsically safe conductors where they are colored light blue and where no other conductors colored light blue are used. Likewise, color coding shall be permitted to identify raceways, cable trays, and junction boxes where they are colored light blue and contain only intrinsically safe wiring.

Did you really mean to say this paragraph requires IS circuits to be blue? It appears to me it allows the lt blue color to serve as IS identification but does not seem to require it.