When UL violates the NEC

[rich000]

What happens when a piece of UL equipment violates the NEC?

For example, we have roof top HVAC units with the wiring inside the air stream (plenum) that is covered in ENT. This to me would violate 2008 NEC 300.22 (B) and (C).

 

[Dennis Alwon]

I had this situation the other day and I started a thread on it. It appears that UL trumps in most cases if the unit is approved assembly for that specific install.

 

[charlie b]

What happens when a piece of UL equipment violates the NEC?

I didn't see the thread that Dennis started, but my reaction to this question is that it cannot happen. Listed equipment is outside the scope of the NEC, and therefore cannot violate the NEC.

 

[raider1]

Bring this to the attention of the listing agency. There are times that listed equipment is manufactured in violation of the UL standards that there are suppose to be listed to.

This exact issue was brought up at an inspectors forum that I attended and the UL representatives said that they would like to hear about these type of situations.

Chris

 

[kwired]

Bring this to the attention of the listing agency. There are times that listed equipment is manufactured in violation of the UL standards that there are suppose to be listed to.

This exact issue was brought up at an inspectors forum that I attended and the UL representatives said that they would like to hear about these type of situations.

Chris

UL and other NRTL's do not go looking for products to inspect, the makers of products come to them. Any listing they give to a product is based on the equipment that was evaluated. They have no way of knowing if there was a change made to a product unless it was presented to them for re-evaluation.

Likewise USDA inspects meat and dairy processing facilities. That does not guarantee that once they approve a plant and leave that things will not change once they are gone. Unlike UL they will come back even if not invited back.

 

[steve66]

Its also quite possible that UL has test the unit, and determined the limited amount of ENT is acceptable.

IMO, having a short piece of ENT in a listed air handling unit is quite different from allowing electricians to run unlimited quantites in a plenum.

 

[Mgraw]

I think you are comparing apples and oranges. A furnace, for example, is built to ansi standards written by CSA. The NRTL is just certifying the furnace is built to those standards. This has nothing to do with the NEC.

 

[Dennis Alwon]

I didn't see the thread that Dennis started, but my reaction to this question is that it cannot happen. Listed equipment is outside the scope of the NEC, and therefore cannot violate the NEC.

This thread about a meter main combo

 

[renosteinke]

Open any UL standard, and it will lead off with a long list of other standards that influence the UL standard. The NEC is but one of these standards.

Look to the NEC, and you will find its' scope is quite limited once you're within an appliance. That's why your toaster needs neither a fuse, nor a #12 cord.

UL isn't about to 'violate the NEC.' That's what has led to decades of waffling about power strips, discussed elsewhere. Look closely at your suspected 'violation.' and I expect you'll find it is outside the scope of the NEC.

The whole point to listing a product is to relieve the AHJ from playing design engineer.

 

[don_resqcapt19]

...UL isn't about to 'violate the NEC.' ...

Then why did they permit electronic switching devices to use the EGC as a current carrying conductor? That permission from UL to use the EGC in violation of the NEC rules is why we now have to run a grounded conductor to switches.

 

[rich000]

Thank you all.

 

[renosteinke]

Don, the NEC never, as best I can tell, forbade the use of the ground wire as a conductor. All the NEC ever banned was 'objectionable' current over it.

Sure, there was some debate at the time, but back then about the only thing that used the ground wire were some illuminated switches. It was also seen as inevitable with certain electronics that there would be some current on the ground wire. Define 'objectionable.'

Enter the new millennium, where various save-the-world types want to mandate all manner of automatic switching. Suddenly, we're looking at a lot more current going over that wire. Plus, we have all those power quality concerns that we were blissfully ignorant of even in 1980.

I don't think the NEC even yet bans current over the EGC; you're just required to run the neutral to the residential switch boxes. Thus, the UL standards are still in conformance with the NEC.

Though I expect that to change ....... that is, I expect the standards to change, in tandem with the NEC changing.

 

[don_resqcapt19]

Don, the NEC never, as best I can tell, forbade the use of the ground wire as a conductor. All the NEC ever banned was 'objectionable' current over it.

Sure, there was some debate at the time, but back then about the only thing that used the ground wire were some illuminated switches. It was also seen as inevitable with certain electronics that there would be some current on the ground wire. Define 'objectionable.'

Enter the new millennium, where various save-the-world types want to mandate all manner of automatic switching. Suddenly, we're looking at a lot more current going over that wire. Plus, we have all those power quality concerns that we were blissfully ignorant of even in 1980.

I don't think the NEC even yet bans current over the EGC; you're just required to run the neutral to the residential switch boxes. Thus, the UL standards are still in conformance with the NEC.

Though I expect that to change ....... that is, I expect the standards to change, in tandem with the NEC changing.

Any current on the EGC, other than fault current, is objectionable to me. If you use the EGC as a normal current carrying conductor, is it still an EGC? I think not.

Grounding Conductor, Equipment (EGC). The conductive path installed to connect normally non?current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.

 

[weressl]

What happens when a piece of UL equipment violates the NEC?

For example, we have roof top HVAC units with the wiring inside the air stream (plenum) that is covered in ENT. This to me would violate 2008 NEC 300.22 (B) and (C).

The appearent 'violation' of NEC rule occurs the following way: NEC rules apply for all possible use of a specific material, installation method, etc. The UL listed equipment undergoes test within specific use and parameters and thus the specific material, instalaltion method, etc. is TESTED to be safe for that specific application and defined use. Most common example is wire sizes, they always seem to be undersized in comparison to the 310 tables.

 

[weressl]

UL and other NRTL's do not go looking for products to inspect, the makers of products come to them. Any listing they give to a product is based on the equipment that was evaluated. They have no way of knowing if there was a change made to a product unless it was presented to them for re-evaluation.

Likewise USDA inspects meat and dairy processing facilities. That does not guarantee that once they approve a plant and leave that things will not change once they are gone. Unlike UL they will come back even if not invited back.

The equipment manufacturer is legally obliged to notify the lister of ANY changes to the listed equipment. That is actually how Federal Pacific actually went under; they failed to notify UL and resubmit their breakers for testing but continued to apply the label after changes were made to those. The ensuing lawsuits killed them.