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NEC vs. UL

NEC vs. UL

NEC vs. UL

(OP)
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?
 

RE: NEC vs. UL

Generally, the NEC applies to field installation and wiring.  Manufactured items and package systems that are shipped pre-wired are generally not covered by the NEC - that is where UL comes in.

 

David Castor
www.cvoes.com

RE: NEC vs. UL

(OP)
True, but Part VII of Article 410, includes detailed requirements regarding the CONSTRUCTION of Listed luminaires, and they are stricter than those of UL 1598.
 

RE: NEC vs. UL

What section of Part VII are you concerned about?   

David Castor
www.cvoes.com

RE: NEC vs. UL

(OP)
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. Please see the 2nd & 3rd paragraphs of my initial post (above), regarding this.

RE: NEC vs. UL

They are 2 different specs for 2 different constructions. The both apply. One is for metal parts that could be contacted by live wires, one is for metal parts that can't be contacted by live wires.

RE: NEC vs. UL

I don't see a 410.18(A) or a 410.28 in the 2008 NEC.  

Also, keep in mind that some lighting "fixtures" are one off designs dreamed up by architects and implemented in the field using manufactured components.  

 

David Castor
www.cvoes.com

RE: NEC vs. UL

410.18 in the 2005 code is 410.42 in the 2008.

RE: NEC vs. UL

(OP)
Sorry - I usually state the edition. Yes, 410.18 in the 2005 code is 410.42 in the 2008. And 410.28 in the 2005 code is 410.56 in the 2008.

RE: NEC vs. UL

The latest edition of the NEC prevails.

RE: NEC vs. UL

Quote:

The latest edition of the NEC prevails.

In most cases that is true, but there are still a few states still on the 2005 NEC and some on even earlier editions.  

And the 2011 NEC is due out soon!

 

David Castor
www.cvoes.com

RE: NEC vs. UL

(OP)
Thanks to all those that replied.

I've asked a number of folks about this, and posted it on Holt's forum as well. To summarize all of it:

(1) Section 90.7 of the 2005 & 2008 NEC roughly states that one need NOT inspect Listed equipment prior to installing it (except to look for defects, or alterations).

(2) Article 410 of the 2005 & 2008 includes requirements regarding the internal wiring, grounding, and construction of luminaires (2008 even states that they shall be Listed).

(3) Luminaires that are Listed in accordance with UL 1598 ("Luminaires")are allowed to be built (including grounding and internal wiring) to less stringent requirements than those of the 2005 & 2008 NEC.

Thus, it seems to me that there are requirements in the NEC (such as those presented above) that apply to NOBODY, regardless of how well-intentioned & well-founded they are.

For anyone that disagrees, please tell me WHO is it that must satisfy Section 410.42(A) of the 2008 NEC (Section 410.18(A) of the 2005 NEC): "Exposed metal parts shall be connected to an equipment grounding conductor or insulated from the equipment grounding conductor and other conducting surfaces or be inaccessible to unqualified personnel."
 

RE: NEC vs. UL

If the local AHJ told someone they needed to comply with that requirement, then that someone would be the WHO.  

As I mentioned in an earlier post, some lighting fixtures are field-constructed using lampholders, sheet metal, and whatever else is needed based on an architect's design.  In those cases, I could possibly see some need for this requirement.

The NEC is an old document that has been revised numerous times.  It is not too hard to find archaic and obsolete references in it.  At the end of the day, it is up to the local inspector to make the interpretation.  In a lot of cases, it's easier to go along with that interpretation than to argue about.

Also, anyone can submit a suggested change to the applicable NEC Code Making Panel for consideration in future revisions.  There is certainly a lot of room for improvement.  



 

David Castor
www.cvoes.com

RE: NEC vs. UL

(OP)
I mostly agree. But I find it hard to believe that anyone would seek the AHJ's opinion regarding the particular construction details of LISTED luminaires.

It's likely that the only time the Article 410 sections I referenced will come into play, will be AFTER there has been an injury or fire. Then an inspector can easily determine that the NEC has been 'violated'; but there seem to be NO identifiable 'violators' (not the installer; and not the manufacturer of the Listed luminaires).

Yes, something should be revised/updated. But not piece-by-piece, ad-infinitum. It seems that the UL and NEC should have consistent & non-redeundant requirements across all applicable standards & articles, where they interface, overlap, etc.

Maybe I will take your advice to send a couple of suggestion forms for the NEC, and to UL.

RE: NEC vs. UL

Quote:

But I find it hard to believe that anyone would seek the AHJ's opinion regarding the particular construction details of LISTED luminaires.

I certainly would not unless the AHJ made an issue of it.   

The NEC and UL will never be totally consistent ("harmonized" is the Standard-writers term) because both are in constant flux.  The NEC is not even consistent with itself in all situations.  

 



 

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