Why can't I find a *Listed* Duct Temperature Sensor

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AtTheKeyboard

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Colorado
Is there any chance someone can help me find a code exception, or some other reason why I can't find a *Listed* Duct Temperature Sensor commercially available?

The following item was submitted, and was returned, as was not listed. This resistor is supplied/monitored by a digital control unit, which is supplied by a Class 2 power source. Am I correct that this must be a listed product, despite being on a Class 2 power system?


As the Contractor was revising the submission, they noted that they couldn't find a listed product. From my follow-up check, I too am not finding any indications of listing, including from some larger/familiar brands, including Siemens and Johnson Controls. I see indications of specification compliance, mentions of NEMA enclosure ratings, EMC compliance, and expected technical terms - but not a listing.


Is it generally accepted that these devices do not need to be NRTL-listed? Is there a reason why?
 

AtTheKeyboard

Member
Location
Colorado
I suspect it's because the hardware connection that feeds this has both limited voltage and current, avoiding both a shock and a fire hazard. - Just hoping someone has seen something more formal in the past - thanks!
 
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hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Is there any chance someone can help me find a code exception, or some other reason why I can't find a *Listed* Duct Temperature Sensor commercially available?

Probably because there is nothing to list. All it is is a thermistor. Who want's it listed?

-Hal
 

AtTheKeyboard

Member
Location
Colorado

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
I think the listing may be because the thermistor is packaged. You would have to look at the listing spec from UL to see what it is about.

Now, if you could get one of those duct sensor manufacturers to use one of those in their product I think you would satisfy your spec. :happyyes:

-Hal
 
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