Class 1,2,3 vs the zones

[tcpolasek]

Main question: Do I use the “classes”(500-503) and “zones” (505 and 506) chapters independently or in conjunction with each other? If yes the where/when and how would I use them?

I have had several Journeymen tell me yes, but when I look at the scope of 505 and 506 I can't help but think that one is just a repeat of the other. A lot of the text also says the same thing.
Can someone help me iron out the details?
I am operating out of the 2020 NEC.

"505.1 Scope.
This article covers the requirements for the zone classification system as an alternative to the division classification system covered in Article 500 for electrical and electronic equipment and wiring for all voltages in Class I, Zone 0, Zone 1, and Zone 2 hazardous (classified) locations where fire or explosion hazards may exist due to flammable gases, vapors, or liquids."
Thanks

 

[tom baker]

I seem to recall there are no applications of Art 505 in the US, and I tried to do a search to find a post about this but could not.

 

[tcpolasek]

I seem to recall there are no applications of Art 505 in the US, and I tried to do a search to find a post about this but could not.

Cloud you elaborate a little bit please on what you mean by "applications"? I would think that zone 2 applies to the area around a gas pump.

 

[tortuga]

Cloud you elaborate a little bit please on what you mean by "applications"?

In United States and Canada historically hazardous locations are generally classified with the Class/Division system.
In Europe and the rest of the world - the Zone system is used.
Some engineers whom do allot of oil and gas work prefer the Zone system, in the lower 48 people use Class/Division system.
Manufacturers prefer the zone system.
Either one is fine.

Main question: Do I use the “classes”(500-503) and “zones” (505 and 506) chapters independently or in conjunction with each other? If yes the where/when and how would I use them?

Cloud you elaborate a little bit please on what you mean by "applications"? I would think that zone 2 applies to the area around a gas pump.

Article 514 applies to motor fuel dispensing facilities, 514.3 in the 2020 NEC shows you what Class / Zone relationships are.

 

[tcpolasek]

In United States and Canada historically hazardous locations are generally classified with the Class/Division system.
In Europe and the rest of the world - the Zone system is used.
Some engineers whom do allot of oil and gas work prefer the Zone system, in the lower 48 people use Class/Division system.
Manufacturers prefer the zone system.
Either one is fine.


Article 514 applies to motor fuel dispensing facilities, 514.3 in the 2020 NEC shows you what Class / Zone relationships are.

Cool another imperial/metric war.

 

[don_resqcapt19]

If the area classification documents required by 500.4 or 505.4, specify the Class and Division system you would use 501, 502 and 503 as applicable. If the documentation shows Zones, you would use 505 and 506 for those areas.

 

[petersonra]

I seem to recall there are no applications of Art 505 in the US, and I tried to do a search to find a post about this but could not.

There are places that are classified in the US by the zone method, HOWEVER, you have to be careful because US and IEC zones and equipment are not the same. I have personally yet to run across any place in the US classified to the zone method, but I have a very small sample set of classified areas to go by. I have been told that the most common reason to classify any area by zones is to be able to use some equipment that is listed that way. However, I think there is some kind of dispensation that allows the use of zone listed equipment in areas classified by class and division so I don't know that would matter much.

Someone once told me that only a P.E. could classify an area by the zone method but the code only seems to actually require that it be a "qualified" person, whatever that means.

 

[tortuga]

Cool another imperial/metric war.

It was a brief war, its long over, as Don pointed out someone needs to put their signature on the system so to speak and pick a system per 500.4 or 505.4.

you have to be careful because US and IEC zones and equipment are not the same.

Can you elaborate on this? Are you refering to Atex 95/100a ? I am not sure if they are.
I am pretty sure Semi conductor plants use zones.

 

[petersonra]

It was a brief war, its long over, as Don pointed out someone needs to put their signature on the system so to speak and pick a system per 500.4 or 505.4.

Can you elaborate on this? Are you refering to Atex 95/100a ? I am not sure if they are.
I am pretty sure Semi conductor plants use zones.

I think equipment listed for US zones has an "A" in it. I have no idea what the difference is.

 

[rbalex]

There are some specific cautions/restrictions for mixing and matching NEC Divisions and Zones in Section 505.7 (Read the whole thing)

The “A” appended to “Ex” required by Section 505.9(C)(2)(3) indicates two things:
1. The evaluation was by an NRTL.
2. The product also meets “ordinary location” requirements. (IEC/CENELEC/ATEX does not necessarily require this)