NEC vs. UL

[rwilsond]

Sometimes there are inconsistent requirements for manufacturers, between the NEC and UL standards. Presently, I'm looking at requirements for manufacturing luminaires, and see some grounding requirements in the NEC, are stricter than those of the UL.

For example Article 410.18 states that exposed metal parts shall be grounded or insulated from ground and other conductive surfaces...

But UL 1598 (Section 6.14.1.2 of the 2004 edition) states that decorative parts, metal guards, metal shades that do not enclose live parts need not be grounded.

Which prevails?

 

[resistance]

re-read what you wrote, then tell us what you think.

 

[cadpoint]

The NEC likes for one to ground the chasis of the device or equipment that one brings power too.. In most cases the lamp shade by construction will become one with the chasis.

 

[resistance]

They are worded different, but require the same in my view.

 

[rwilsond]

They are worded different, but require the same in my view.

I sense some 'resistance' here.

They are not the same. Consider a cord-hung fixture with easily-accessible metal decorative parts that come into contact with other metal parts, and is in close proximity to the 120 VAC cord. The NEC requires that these metal parts be grounded.

But the applicable UL standard (1598) allows the manufacturer to "List" the fixture, without grounding the decorative parts (since they do not enclose live parts).

 

[Pierre C Belarge]

rwilson
I do not have a copy of the Standard, so it is difficult to properly answer your quetion, but I am going to try anyway


The Standard may have some differences from the NEC, but the process of a manufacturer getting a listing from a NRTL may shed some light on this. The process of listing will require some testing, etc... in that process the NRTL can determine if the decorative parts may become a hazard without the bonding/grounding of parts.

 

[rwilsond]

rwilson
I do not have a copy of the Standard, so it is difficult to properly answer your quetion, but I am going to try anyway


The Standard may have some differences from the NEC, but the process of a manufacturer getting a listing from a NRTL may shed some light on this. The process of listing will require some testing, etc... in that process the NRTL can determine if the decorative parts may become a hazard without the bonding/grounding of parts.

Many manufacturers are UL shops (i.e., they are at liberty to place the UL "Listed" label on their products). Let's say such a manufacturer produces fixtures that comply with the UL standard (and they place "Listed" labels on their fixtures). These fixtures are then installed by qualified electricians that follow the NEC. But it is all at risk of having a NEC-savvy inspector noticing that the fixtures don't satisfy the grounding requirements of Article 410 of the NEC.

What would be the manufacturer's defense?

 

[don_resqcapt19]

The code does not apply to a the making of a listed product. The code only covers the installation of that product. Note that this is a general comment as there are some sections of the code that have product construction specification, but this is not one of them

 

[Pierre C Belarge]

Many manufacturers are UL shops (i.e., they are at liberty to place the UL "Listed" label on their products). Let's say such a manufacturer produces fixtures that comply with the UL standard (and they place "Listed" labels on their fixtures). These fixtures are then installed by qualified electricians that follow the NEC. But it is all at risk of having a NEC-savvy inspector noticing that the fixtures don't satisfy the grounding requirements of Article 410 of the NEC.

What would be the manufacturer's defense?

The product at one point was evaluated by UL. The product will be periodically evaluated again, more often if there is a complaint.

There will be times in this industry where an inspector may or may not accept the NRTL sticker. Then lots of discussion on the job occurs and not all situations are resolved in the same manner.

If you have a situation where you are not sure, one solution is to discuss it with the inspector prior to installation.

 

[rwilsond]

The code does not apply to a the making of a listed product. The code only covers the installation of that product. Note that this is a general comment as there are some sections of the code that have product construction specification, but this is not one of them

True, the 2nd paragraph of Section 90.7 of the 2008 NEC states the "intent" of the NEC, such that "Listed" equipment need not be inspected, except to detect alterations or damage. And Section 410.6 requires all luminaires to be "Listed".

So, the responsibilities are clear (the manufacturer builds & Lists luminaires per UL 1598, and the electrician installs them per NEC)... until one sees Part VII of Article 410, which includes detailed requirements regarding the construction of luminaires (that are stricter than those of UL 1598).

 

[don_resqcapt19]

...
So, the responsibilities are clear (the manufacturer builds & Lists luminaires per UL 1598, and the electrician installs them per NEC)... until one sees Part VII of Article 410, which includes detailed requirements regarding the construction of luminaires (that are stricter than those of UL 1598).

I guess I should have looked at the Article before posting, but I still don't see the grounding rule in Part VII.

 

[rwilsond]

I used Part VII as an example. What interests me the most are actually: 410.18(A), 410.20, 410.28. These requirements seem to apply to the manufacturing stage of the fixture.

For example, should a manufacturer disregard NEC 410.18(A), as long as he has met the less-stringent requirements of the applicable UL Standard (1598)? It could be a huge loss if he makes 100's of them, and they are rejected after installation, for improper bonding/grounding of the non-current-carrying metal parts.

 

[don_resqcapt19]

I used Part VII as an example. What interests me the most are actually: 410.18(A), 410.20, 410.28. These requirements seem to apply to the manufacturing stage of the fixture.

For example, should a manufacturer disregard NEC 410.18(A), as long as he has met the less-stringent requirements of the applicable UL Standard (1598)? It could be a huge loss if he makes 100's of them, and they are rejected after installation, for improper bonding/grounding of the non-current-carrying metal parts.

I don't see where the manufacturer of a listed product has to comply with code sections that do not specifically apply to the construction of the product. In the case of this article the only rules that the manufacturer has to comply with are those in Part VII and those in the UL standard that his fixture is listed under.

 

[rwilsond]

Thanks. But somehow, it seems that the various exposed non-current-carrying metal parts of a luminaire must be made to comply with the grounding/bonding requirements of the NEC (including those outside of VII).

So, let me pose the question from another angle. Whose responsibility is it to comply with Section 410.42(A) "Exposed Conductive Parts" of the 2008 NEC for a hanging luminaire? Is it the manufacturer's responsibility, or is it the installer's responsibility?

If you say it's the manufacturer's responsibility, I'll remind you that 410.42(A) is not part of VII (the 'Construction' part of the article), and that the manufacturer complied with the UL standard 1598, and gets LISTED labels on his luminaires. And, let's say for the sake of discussion that he fully complies with VII of the NEC.

As for the installer, I doubt any qualified electrician would dare attempt to start grounding/bonding various parts of a LISTED luminaire. He simply connects the ground wire from the ceiling box to the canopy and moves on.

 

[don_resqcapt19]

I don't see any need for the installer to make modifications to the listed fixture to bring it into compliance with the code sections you are citing. There are lots of applications where the manufacturer of a listed product is permitted to do things that are not permitted by the NEC.

 

[rwilsond]

I don't see any need for the installer to make modifications to the listed fixture to bring it into compliance with the code sections you are citing. There are lots of applications where the manufacturer of a listed product is permitted to do things that are not permitted by the NEC.

But why would there be requirements in the NEC that do not pertain to either party (not to the manufacturer, and not to the installer)?