UL required in the US?

UL in the US...

I get asked this a lot but have never been able to find a clear cut answer.

Internally we have always required all devices used in equipment to be UL approved.

I read recently that NEC 70 Article 409 states devices are to be UL approved. But find it anywhere. I was also told in a safety class that NFPA 79 requires all components to be tested by an NRTL. But also couldn't find anything stating this.

Anyone have anything that will clear this up for me.

Alot of answers I find tend to say "Depends on the AHJ, or how an inspector is doing that day".

(Sorry for the double post, I added the same question at the end of another UL thread. I figured I would have better chance with a new thread)

This one gets miss-understood by about 90% of the people I come across (in the Automation world). UL isn’t standard, they are a testing laboratory that tests to other standards. The NFPA, (National Fire Protection Association) as well as the NEC (National Electrical Code) creates and publishes literally thousands of standards including standards used in the Automation world. In my past life I worked for a company that sold radio modems and I would routinely get asked “are your antennas UL approved?”, my response was “to which standard?” because there isn’t a safety standard that covers antennas (outside of installation). When something has a UL label on it, it means that it has been built to meet any safety standards that apply to the type of product and the market which it is sold into. For example, NEC 409 (the “70” is actually an NFPA code) covers Industrial Automation Control Panels that are intended for general use in ordinary locations using 600V or less.
Having said all of that (and I could go on for many pages), it is a very complex system of standards, testing (which is where UL and others come in) and enforcement and over time it’s all been lumped together and called “UL”.
I can’t publish it (because it’s probably copy protected) but do a search for “Kendal Electric NEC 409” and you should find a PDF that they produced that doesn’t directly answer your questions but it should give you a good idea of how the safety standards work.

UL, and NEC, and FM are not laws and of themselves have no mechanism to force compliance.

However, many local jurisdictions (i.e. states, counties, municipalities, etc.) cite the above-mentioned organizations' standards in their ordinances and statutes. This does make compliance a matter of law in that jurisdiction.

It is important to note that these standards organizations are safety oriented, and compliance is intended to make it difficult to electrocute yourself. A component or a panel can be fully in compliance with UL, for example, and not work worth a damn.

Firejo said:

“Kendal Electric NEC 409” and you should find a PDF that they produced that doesn’t directly answer your questions but it should give you a good idea of how the safety standards work.

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I did a search for this but could only find a power point covering SCCR.

Tom Jenkings said:

UL, and NEC, and FM are not laws and of themselves have no mechanism to force compliance.

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Understood. The way it has been explained to me is that it is indirectly law based on the OSHA general duties clause. So even though it isn't law you can still be fined based on not following known good practices and standards.

I'm just surprised that there isn't anything for components. Like Circuit breakers, there is a UL standard for molded circuit breakers and Power supplies... But by what you guys are saying even if a standard says must meet NEC/NFPA/ISO yadda yadda these standards don't require components be UL approved.

It all seems so grey and unclear... Same goes for machine safety...
If a question is asked on this forum about safety on this forum the first response is what does the risk assessment say.

In the US a Risk assessment isn't required by law... Unless you count indirectly via the General Duties Clause.

Sorry, a little bit of a side rant there...

Please correct me if I am wrong on any of this. Still learning and studying all of this.

So I think I found the answer to my question.

I most of the sections (in NFPA79) I see that it uses the phrase 'Listed'...

Example:
5.3.2 Type. The supply circuit disconnecting device shall be
one of the following types:
(1) A listed motor circuit switch (switch disconnector) rated
in horsepower

Then by the definition of Listed:
Equipment, materials, or services included in a
list published by an organization that is acceptable to the authority
having jurisdiction and concerned with evaluation of
products or services, that maintains periodic inspection of
production of listed equipment or materials or periodic evaluation
of services, and whose listing states that either the equipment,
material, or service meets appropriate designated standards
or has been tested and found suitable for a specified
purpose.

So the sum of all that seems to point that as long as a section states a device must be 'Listed'. Means that it must be approved by a NRTL, UL for example.

Does this seem correct?

Tom Jenkins said:

UL, and NEC, and FM are not laws and of themselves have no mechanism to force compliance.

However, many local jurisdictions (i.e. states, counties, municipalities, etc.) cite the above-mentioned organizations' standards in their ordinances and statutes. This does make compliance a matter of law in that jurisdiction.

It is important to note that these standards organizations are safety oriented, and compliance is intended to make it difficult to electrocute yourself. A component or a panel can be fully in compliance with UL, for example, and not work worth a damn.

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This has been my experience.

Generally, I've found two reasons a panel needs to be UL certified:

1. The End-user's policy is to have all equipment have a UL sticker. (Generally large companies)

2. The local ordinance / law states that equipment must have a UL sticker.

In the second case, you will often find that OEMs make equipment that might be in 30 plants across the US - and only 1 will be different because that county has a law about UL certification.

Personally, I go ahead and make all of our panels 'UL' compliant. For the most part, you are just providing extra information.

[Plus - if you switch to using Class 2 power supplies - you can get away with Non-UL listed components.]

First off, the "NEC" is actually / officially NFPA 70, they are not different standards, they are different names for the same standard.


Each state has its own rules as to a) whether they "adopt" the NEC and b) which VERSION they adopt; it is not uniform across the country. Below is a map showing the adoption across the US (as of the time of this posting):



WITHIN the NEC, there is no provision directly REQUIRING listing by UL or any other agency, collectively referred to as "NRTLs" for Nationally Recognized Testing Labs. But what there is are several places within the NEC imposing requirements that can only be met by having an NRTL listing. I know, it's semantically similar, but not exactly the same thing.

ONE of those areas is Article 409, which requires that Industrial Control Panels be marked with a Short Circuit Current Rating (SCCR), and that the SCCR be obtained by "an approved method". It then goes on, in an "Informational Note" to tell you that one such "approved method" is laid out in UL508A Supplement SB. the fact is that unless ALL of the components have been assembled and TESTED by the manufacturer, UL508A is actually the only PRACTICAL method of attaining it.

In addition, Article 90.7 Examination of Equipment for Safety, goes on to say:

It is the intent of this Code that factory-installed internal
wiring or the construction of equipment need not be
inspected at the time of installation of the equipment, except
to detect alterations or if the equipment has
been listed by a qualified electrical testing laboratory that is
recognized as having the facilities described in the preceding paragraph and that requires suitability for installation in
accordance with this Code.

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What that means is that you don't HAVE TO use an NRTL for listing, but if you don't, you are subject to the local inspector doing it. Most inspectors that I run into are LOATHE do do this, it takes a LOT of time in the field. So to "punish" you for forcing them into it, they ALWAYS find something wrong. ALWAYS... That then means red-tagging the entire project until it is corrected, and that will cost money and consternation that nobody wants. That said, many jurisdictions will have a requirement for an NRTL listing, usually with a "limit" of the number of devices in an assembly below which a listing is not required. For example here in California, it is 5 devices in an assembly, including the box. that can vary by location and by the nature of the components involved.

Next, the NEC has a section on "definitions", Article 100, within which is the following:

Listed. Equipment, materials, or services included in a list
published by an organization that is acceptable to the authority
having jurisdiction and concerned with evaluation
of products or services, that maintains periodic inspection
of production of listed equipment or materials or periodic
evaluation of services, and whose listing states that either
the equipment, material, or service meets appropriate designated
standards or has been tested and found suitable for
a specified purpose.

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Followed by another "informational Note";

Informational Note: The means for identifying listed
equipment may vary for each organization concerned with
product evaluation, some of which do not recognize equipment
as listed unless it is also labeled. Use of the system
employed by the listing organization allows the authority
having jurisdiction to identify a listed product.

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All by itself this can be loosely interpreted, but in many places within the NEC (too numerous to post), you will find the term "listed" or "listed assembly" for all manner of devices.

Also, "Labeled" is defined:

Labeled. Equipment or materials to which has been attached
a label, symbol, or other identifying mark of an
organization that is acceptable to the authority having jurisdiction
and concerned with product evaluation, that maintains
periodic inspection of production of labeled equipment
or materials, and by whose labeling the manufacturer
indicates compliance with appropriate standards or performance
in a specified manner.

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Finally, NEC section 110.2

Approval. The conductors and equipment required or
permitted by this Code shall be acceptable only if approved.
Informational Note: See 90.7, Examination of Equipment
for Safety, and 110.3, Examination, Identification, Installation,
and Use of Equipment. See definitions of Approved,
identified, Labeled, and Listed.

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Approved by the way just means "acceptable to the Authority Having Jurisdiction" (AHJ).

So what happens is that each state, municipality, county etc., in adopting the NEC (if they do), will have a section of the local electrical code delineating WHICH of the many NRTLs are acceptable to them. As a gross general rule, most of them defer that to a list maintained by OSHA in the link below:
https://www.osha.gov/dts/otpca/nrtl/nrtllist.html
UL is just ONE OF the NRTLs on that list. However it should be noted that, with the exception of CSA, most of the other NRTLs will use UL's standards for testing equipment.

So bottom line, the NEC does not specifically SAY that you must have UL listings, but it is implied in many places that you must meet standards, and UL is the standard to meet.

Thanks for all of the information guys. I think I have a better understanding of it now.