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Which standard to use ISA 60079 or UL 60079?

Which standard to use ISA 60079 or UL 60079?

Which standard to use ISA 60079 or UL 60079?

OSHA now recognizes both the ISA and UL 60079 series of standards for product safety testing (see OSHA Appropriate Test Standards)of equipment intended to be installed in hazardous locations.

While I suspect they’re identical, I’m not sure and I’d rather not invest +$3,000 for the UL set and another +$3,000 for the ISA set only to find out they’re the same. I’ve searched the web for some document that might clear it up for me, but haven’t found anything.

I’m working with someone who wants to get product approval based on 60079-15, believing the costs would be less for any additional standard which may be needed for marketing the product in other countries that accept the IEC-60079 series of standards.

I’ve read UL’s response to the initial OSHA proposal to add these standards (Docket No. OSHA-2013-0012) and they’re response with:
“UL particularly applauds OSHA’s decision to recognize the IEC-harmonized Zone standards published by ISA and UL”

I guess this statement isn’t definitive enough for me. Can anyone offer some additional references?


"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."

RE: Which standard to use ISA 60079 or UL 60079?

From my understanding...
UL 60079 and ISA 60079 are identical except for any country specific requirements (National Differences)...
They are identical but IEC may have a "national difference" that your instruction manuals also be available in French language..

So my answer to you is IF you only intend the product to be sold/used in the US then UL is really all you need.. If you will ever sell/use it outside of the US then go for the ISA standard and any others..

When we go through testing they typically only charge us a few dollars, if that, to get both UL,IEC,EN/CSA approvals since they are so similar and so far 100% of the time the differences are so small that it doesn't make any sense to purchase both standards.. We get access to all UL standards and design to that.. Then they might just come back and say.. "To get IEC you just need to include these 2 warnings in French and if a customer requests you will need to provide instruction manuals in German or similar minor requirement."

Its really a big joke IMO.. UL wants their money, IEC wants theirs,etc... But they all have the same requirements..
First time I ran into this we were going through UL and decided to also get CSA approval.. Well we paid for the "CSA" standard and when we received it the standard was 100% identical to the UL one except at the top of each page instead of just saying "UL" it said "UL/CSA"

RE: Which standard to use ISA 60079 or UL 60079?

Thanks for the input. I was able to get Part 0 and 15 of ISA-60079 (waiting on the others) and both have an annex for the US differences. The documents all have both the ISA and UL Logo at the top of the page. Intertek confirmed that the UL version has the ISA logo at the top of it as well.

My frustration is that I find myself educating the NRTL as to the requirement. Intertek though that they were accredited by OSHA to use either the ISA or UL version of 60079 and I was amazed that I had to show them why they're not and that any money I pay to them for a certification to the standard has no validity in the US until they are accredited. They're now scrambling to get their accreditation. My other concern is that they're telling me I have another standard along with 60079 that the equipment has to be tested to, but can't give me the "Legal Bases" for the requirement.

TUV did the certification for the ATEX approval but can't provide a report that documents their testing, which would have let Intertek relax some of the requirements.

My former boss, and mentor, referred to them as "publishers". He wasn't that far off.


"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."

RE: Which standard to use ISA 60079 or UL 60079?

"no validity in the US" - Not true, UL isn't the only safety agency in the USA; they don't set the 'standard'.

Back to your original question, the safety standard in the USA is defined in the NEC, NFPA 70. Article 501 references ANSI/ISA 60079-* in the Informational Notes (i.e. reference material). Occasionally they will reference an ANSI/UL spec thta doesn't have an ISA equivalent (such as ANSI/UL 913) but again, these are for reference only.

If your customer wants to integrate your equipment into theirs and then get a UL Listing on the top level equipment, then you are stuck with using UL 60079; otherwise UL will charge to repeat all the work.

If your customer doesn't require UL (and neither will future customers...), then use a non-UL NRTL.

That being said, which to buy is still tricky. UL 60079 excludes requirements in ISA 60079 (why exactly is aluminum dust not an issue in the USA? - that was discussed in another thread). Others can probably mention other topics where UL has stricter requirements that I'm not thinking of at the moment.

If most of your customers are in the USA then buy UL; other NRTLs can test against the ISA standard and there is a high probability you won't have major redesign costs. If most of your customers are around the world then get the ISA standards.

I started with the ISA standards, but eventually had to buy the UL standards as my ISA standards were expired by the time I got to a USA project...


RE: Which standard to use ISA 60079 or UL 60079?

My comment regarding "...no validity in the US...", was that if the lab, using the standard, wasn't accredited by OSHA to use the standard for testing, the certificate issued by them isn't valid.

Yes, I agree, there is an ISA, FM, and UL standard for "non-incindive" listing. The FM and UL standard both reference the ISA standard, which is a US derivative of the IEC standard. While the NEC may define the standard, OSHA determines the lab and the standard. You'll find that NEC never referenced the IEC standard until after OSHA accepted it some 3 years ago.

I have since read in the ISA version of the IEC 60079 series, that the standard is jointly published by UL and IEC. The OSHA NRTL site also references both standard bodies. At this point I'm just waiting for the Labs to get their accreditation from OSHA to use the standard. Intertek applied for this in June or July of this year. I'm sure others will follow.


"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."

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