Class II, Div 2 - 'Dusttight' Photoelectric Sensors

Micki

Member
Location
New Zealand
Occupation
Electrical Engineer
We design and build industrial machinery for international markets (North America / Europe / Asia / Oceania). We try to create designs where only minimal changes need to be done to comply with all relevant standards for each market. We also try to avoid intrinsically safe circuits wherever possible.

The machines have an internal Class II, Div 2 Location (Zone 22 for EU).

It's incredibly hard to find sensors with ratings for all markets (NA HazLoc Class II, Div 2 and ATEX Zone 22 and IECEx Zone 22).

Question: Is a photoelectric sensor that is not identified / marked for Class II, Div 2 acceptable if it is 'dusttight' (it has an IP65 rating, unfortunately no NEMA rating. The sensor is also ATEX and IECEx rated for Zone 22, however I know this is not recognized in the US)?

As I understand a sensor would fall under NFPA 70, Article 502.150(B) (Signaling, Alarm, Remote-Control and Communication Systems; and Meters, Instruments, and Relays). How is the term 'dusttight' generally interpreted and who makes the call if something is acceptable? Is the IP code system generally accepted in the US? Is the final interpretation all up to the AHJ?

We did use an intrinsically safe PE from Banner in the past that is rated Class II, Div 2 - unfortunately this sensor is only rated for gas atmospheres under the ATEX & IECEx schemes so we can't use it outside North America, it's a pain because just about all intrinsically safe photoeyes we found are only gas rated for EU.

Does someone know of a through-beam or retroreflective photoelectric sensor with Class II, Div 2 marking that doesn't require an intrinsically safe circuit?
 
If "6" is the first digit in the IP number, it is dust tight, and I would approve that for use in in a Class II, Division 2 location as I would consider that "otherwise identified for the location".
502.120(B)
(3) Resistors.
Resistors and resistance devices shall have dust-ignitionproof enclosures that are dusttight or otherwise identified for the location.
502.150(B)(3) sends you to 501.120(B).
 
If "6" is the first digit in the IP number, it is dust tight, and I would approve that for use in in a Class II, Division 2 location as I would consider that "otherwise identified for the location".

502.150(B)(3) sends you to 501.120(B).
Thanks a lot for your response. Yes, it is. It's IP65. Would an AHJ have any grounds to reject it?
 
Thanks a lot for your response. Yes, it is. It's IP65. Would an AHJ have any grounds to reject it?
Everything has to be approved by the AHJ....110.2. Few are familiar with the IP ratings, but I think if shown the IP rating descriptions and comparing them the the NEMA ones, most would accept.
The note at the bottom of Table 110.28 in the 2023 NEC says:
The term dusttight is typically used in conjunction with Enclosure Types 3, 3S, 3SX, 3X, 4, 4X, 5, 6, 6P, 12, 12K, and 13.
When you do a compassion between NEMA ratings and IP ratings. NEMA 12 is often specified for dusttight, and most show IP 54 as the equivalent. Not sure I agree that IP 54 is equivalent, but IP5x is only limited dust protection and I don't see that as dusttight. IP6x is for "full dust protection" and I see that as being a dusttight enclosure.
 
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