Communication Methods for LED Signs / Electronic Message Centers: Wireless, Hard Wired, or Both?

LED Signs communicate information to the public, but how do you decide the best way to communicate to the sign? There are many ways to do this and each option has its own pros and cons, depending on your specific installation type.

There are (3) types of approaches to communication: wired, wireless, or both. Some locations have existing hard wiring to the sign site, others are more remote and using a cellular modem is the only realistic option.

WIRED (HARD LINE)   

  

In the past, before high speed networks were common, LED signs were usually hardwired using a phone modem or serial cable (RS485 or RS232). These options were fine back then, because the signs were less sophisticated and the actual data sent to the sign was minimal. As LED sign technology expanded, larger file sizes were required. These options became less common and were replaced by standard Ethernet network cable or Fiber Optics. The older options are still used in special situations like factory production floors where they have a large serial network with simple machine code, but for the commercial market Ethernet and Fiber have become the standard wired solution.
 
 
Ethernet TCP/IP  (Cat5/6 Cable - RJ45 Ends)

 
This is a common option for wall mounted signs, or street signs that are closer to the building or network drop, where the cable run is less than 300 Ft. Most LED sign manufacturers offer this connectivity imbedded into their system without any special adapters. Signs that require separate “Ethernet Adapters” may be using older Serial based controllers.

• Maximum run is 300ft without a network switch in the middle to boost the signal.
• Less fragile than Fiber Optics. Harder to damage.
• Ethernet networks are very common, and the cable is inexpensive.

Fiber Optic Cable

 
Although somewhat rare in commercial LED sign installation, Fiber is still commonly used in the military. Data is sent using light signals across refined glass strands that make up the fiber optic cable. An “Fiber Optic to Ethernet” converter is usually required on both sides of the system: one placed at the sign, and the other at the building where it connects to the main Ethernet network.

• Long distance capability near 40 miles with Single-Mode (more expensive), and 10 miles using Multi-Mode (less expensive).
• Fragile, and can be expensive to run and repair if damaged.

WIRELESS

  
You can get Wireless Radios that connect to serial networks, cellular networks, and standard Ethernet TCP/IP networks. Many frequency standards can be used, but the most common ranges are 900 Mhz, 2.4 Ghz, 5 Ghz and Cellular. Wireless radios have become the standard option for most manufacturers because they allow for a broad range of installation types, and can save time and money by not having to run a hard line in the ground.

Wireless is best when you have an LED sign that will be within 100-200 yards of the transmission point with clear “Line of Site” (no buildings or metal walls between the radios). The most common configuration  is (1) wireless radio installed at the sign, and (1) at the building. You connect the building radio to your network, or computer directly and the radios function as a long wireless “cable” connecting you to the sign. Other configurations can be used depending on the installation like Point to Multipoint, WiFi Access Point, and others.  

Common Frequency Types:

900 Mhz (slower data rate, longer distance): These were much more common in the past, when serial networks abundant. However, there are products out there that will use a multi channel 900 Mhz signal with a standard ethernet network to boost the data rate. These radios are best used for installation with special needs like distance or if the signal needs to go through structures between the sign and the transmission point.

2.4 Ghz (standard WiFi frequency): These radios are the most common, and have a good balance of distance and data rate. 2.4 Ghz is the most used frequency in the USA for home and commercial WiFi networks. This poses a slightly larger security risk for your sign, if the radios are not secured properly. (Deacon’s post on LED sign security)

5 Ghz (higher data rate, more secure): This frequency is less common than 2.4 Ghz, making it a bit more secure because most hackers are not looking for signals in the 5 Ghz range. You also avoid possible interference from other 2.4 Ghz devices in the area. Many manufacturers are leaning toward this option as the default choice for LED signs.

Cellular Modem

Another wireless option is a Cellular Modem. These are gaining popularity, but are less commonly used for LED signs. They provide access to the sign over the same data network as your smart phone (3g, 4g, LTE, etc..). Without getting too technical, the system works like this:

After purchasing a “Data Only” monthly plan through a wireless carrier supported by the Cell Modem (ATT, Verizon, T-Mobile, Sprint),  the wireless provider will then provide an external internet IP address for the Cell Modem to use. The Cell Modem is installed and connected to the sign (likely using a secured router). You can then send messages to the sign over the internet by using the unique IP address previously provided.

This option is best used for signs that are controlled off-site, in remote locations, or outdoor digital billboards.

WIRELESS AND HARD LINE

I’ve been on installations who utilize both options as a fail-safe measure when the sign is providing mission critical data. This is more common in a military setting, but I’ve seen schools and other government organizations use this approach. For the average user, I believe it’s overkill, but if you do decide to take this route make sure you communicate this to the manufacturer. Some manufacturers will need to put an extra “Network Switch” inside the sign, and this can be an extra fail point. Others will have multiple network ports built into their sign control unit, a much better solution in my opinion.


Conclusion

The bottom line is, make sure you work with the manufacturer or LED sign dealer to get the best solution for your installation. Not being able to communicate with your brand new sign because the communication method is in-correct can really ruin the excitement of the moment. If your manufacturer doesn’t pre-program street ready messages on the sign, you may be stuck with “Sign Test 3” scrolling across the sign until the communication is fixed.

Make sure your manufacturer secures the wireless devices prior to shipment, and allows you to configure them with your own security measures if needed. Communication to your sign is a fundamental necessity, make sure you get the best solution and equipment from your manufacturer.


-Scott Hofheins



I hope this post has been informative and helpful. As usual, I welcome ALL constructive comments. Please feel free to comment and add anything I’ve missed, or additional tips you may have regarding this topic. Please visit www.vantageled.com for many other resources, white papers, and of course: Great looking LED Signs!

**All posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

Power Cost of LED Displays

- Mike Prongue 

Many very technical people in the Electronic Message Center (EMC) industry, those who are licensed in electrical and in state construction regulations, look the other way and suddenly seem to want to change the subject when this innocent question is asked by a curious customer:

“What will this cost me to run?”

There is no reason to panic! And, better still, this question is a buying signal. If the customer has gotten this far into their evaluation of a possible EMC for their business, now is not the time to "freeze up". A great reply to this question may seal the deal for you.

It’s a very simple question to answer and you can start by calling your power company, or searching online for their price per kilowatt of power. If you don’t even want to do that, use the average of 10 cents per kilowatt ($.10).

Next determine the power consumption of the EMC in watts. This information has been provided by the manufacturer. If you do not have the watt specification then you will have the amperage draw of the EMC.

Remember that Watts = Amps x Voltage. So if you have an EMC rated at 10 amps, and it is installed in a 110 volt service, you have 10 (amps) x 110 (volts) or 1100 watts of power consumption (per hour).

1100 watts of power is 1.1 kilo Watts of power, of course kilo means “thousand”. We already determined the cost of power was  five cents per kilowatt.

If the customer runs the display non-stop, at peak power, displaying all lamps all of the time for24 hours per day, then it will cost approximately:

1.1 (kilowatts)   x   .10 (cost per kilowatt)  x   24 hours   =   $2.62* per day.

If it is a double-sided EMC, then the cost would double to $5.24 per day if the EMC ran at maximum output, all the time, no slide transitions, no interruptions, fully illuminated.

Simply because no EMC, in use by a customer, runs at maximum output all the time, you should use an very realistic percentage of max power when estimating average power consumption-- 30% of max. Just tell your customer to expect about a 1/3rd of maximum cost- even more affordable - $5.24 x .30  =  $1.58* per day!

This is a great investment. What other form of advertising only costs  $1.58 per day for thousands of exposures to thousands of customers (driving by)? Now you can share this great advertising deal with your customers- head held high, ready to impress!

Now close that sale!

* Always check with your local power company for peak/ off-peak rates, and understand that this article is a general statement on the subject and not specific to your project.

**Note all posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

LED Sign 101: Myths and Misunderstandings about LED/EMC/Digital Signage

-Deacon Wardlow

Technology is confusing. Looking from the outside-in, one would think the people in technology-sector jobs work hard to keep it that way. NITs, Lux, Flux, EMC, LED, EDS, OOH, DOOH, OA, IC, RJ-45, DVI, HDMI, and the alphabet soup list goes on and on. To clarify things I put together an online (PDF) reference guide (The ABCs of LED Displays); there are still a lot of myths and misunderstandings about LED Signage out there and it almost seems like you need a “Geek Speak” interpreter so here are a few of my favorite myths/misunderstandings simply answered and explained.

LEDs last forever!
That’d be great, but unfortunately, this is not the case. Most LEDs sourced for LED Signage are carefully qualified to last 100,000+ hours (24/7 = 11.4 years, 18/7 = 14.8 years, 12/7= 22.8 years, 8/7 = 34.2 years... a fairly long time for a produced light source!). With proper care and strategic use of heat sinks, it’s possible to get even more optimal lifetime performance before the LED is no longer good. What happens at the end? LEDs don’t really “die” like other light sources. They gradually dim over time. Given enough time, they reach a point where they degrade beyond usefulness (the agreed upon level is less than 70% of the original starting brightness levels = LED “death”).

There’s a bright-light race in the industry and some companies will stoop low to achieve high light levels. Be cautious about manufacturers who tout super bright LEDs, it’s possible they’re overdriving the LED (running a larger amount of power than is recommended and thus increasing the light output, but shortening the lifetime of the LED). Many achieve brightness through fair-play practice, but “caveat emptor” (buyer beware) still reigns out there.

All LED Signs are the same...
With LED signs (as with life) not all things are equal. You’ve got to dig deeper and go beyond the LED. There was a time when due diligence meant what LED is the company using, that’s simply not enough. It’s important to know the LED source is solid and proven to last, but you’ve got to check the other components. Are the power supplies good? How does the manufacturer prevent oxidation on sensitive contacts and leads on the PCB (printed circuit board) in their sign and in the components? Is the software simple to use? Are the communications reliable (and if wireless, do they operate in the 5GHz range as opposed to the 2.4GHz (2.4GHz is more prone to interference)? A knowledgeable salesperson should be able to explain all this and more in easy-to-grasp terminology an show how the overall system performs to meet your needs.

Virtual Resolution is a sham!
This is only true if the manufacturer represents a “virtual” system as containing the same quality as a real pixel (for example a 20mm 64x128 LED sign which is virtualized, saying it’s the same as a 10mm 128x256 LED sign). You can read more on virtualization here.

Size doesn’t matter...
Not true with LED Signage. Make sure what you’re getting quoted is based on the matrix (number of pixels high by number of pixels wide). Some manufacturers and resellers go by size alone. Check this blog on size issues. Systems are rarely standardized across manufacturers and unfortunately this means the retainer (border, if one exists) can be anywhere from 1.5” around the viewing size to 7”. That’s a fairly large difference.

There’s a lot of misdirection and half-truths out there. Please take the time to dig deeper and learn more about the product line before you buy so you’re sure what you’re getting is what you want. A little time spent up front to ensure you’re getting the best system at a fair price will save you a lot of time and money on the back end.

*I invite you to comment here and/or email me directly with requests at deacon@vantageled.com. Vantage LED has white paper resources and more educational material on the website (http://www.vantageled.com), please check it out when you have a moment. Note all posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

Finding a Quality Sign Installer for an EMC or LED Sign Project

Finding a good company to install your very expensive LED sign can be challenging. You want to get a good price and high quality work but there are some obstacles to overcome. Some areas have many companies to choose from, others have very few. How do you find the best installer for your money?

I would like to share some tips I’ve learned over the years, and hopefully save some time and money for those who are entering the world of LED Signs, Video Boards and Electronic Message Centers. 

Research is Key
The internet has provided many sources and ways to research any topic, sign installation included. I’ve listed a few good sources below:

• SignSearch: This site allows you to search for anything sign related, installation included. I usually select “Have a sign installed” and simply put “Pole Sign” or “Wall Sign” in the description field. Companies are then listed, and you can check out their services, contact info and website.
• Google Maps: This is pretty straight forward. Just search your organization's address. Once it pops up on the map, click the “Search Nearby” link, and type “Sign Installation” or something similar. This will show a nice geographic location of businesses in your area that have something to do with signs and/or installation. 
• SignWeb: This has some good directories, similar to SignSearch.

Referrals are also a great way to find good installers. Ask your neighbors who they used for their sign installation, and if they had a good experience. Also, your LED sign supplier might have some good contacts for you.

Qualities to Look For

• Equipment “In-House”: I have used several companies in the past that outsourced their entire crew and have done an outstanding job. But for the most part, having cranes, bucket trucks, and installation crews all in-house is preferable.  In-house equipment means that scheduling and implementing your installation happens much more quickly than someone who is relying on a third party.

• Sign Company or “Install Only” Company: I have had success with both types of businesses, but I tend to lean toward finding a company who just does installations. If you need fabrication done (pole covers, painting, ect..) in addition to the installation, a sign company that also specializes in installations might be the way to go.

• Experience With LED signs: More and more business are using LED signs, so many installers have at least a little bit of experience with LED signs.

• Licensing and Insurance: Every installer should be licensed and insured in the state/county/city they do work in. Using unlicensed or non-insured installers can cause many long term installation and legal  issues. Most installers will give you their license number to verify.

• Fast Communication: How quickly a company responds to a quote request, is often a signal of how quickly they will execute your installation. Avoid installers who never seem to be available via telephone, or email. This can signify a lack of organization that will ultimately affect your installation schedule.

Getting Quotes
Narrow your search, but try to get quotes from 3-5 different companies.. This will help you get a better feel for a reasonable cost for your installation and give you more chances to see how quickly each company will respond during the quote process.

Make sure to be very clear on the “Scope of Work” for your installation, so there are no unexpected charges. Here are some general items that should be covered:

• Pre-Installation Site Survey: The installer should see the site prior to installation to verify power, access, existing structures, and other important items
• Permits: Are they required? (See my series on permits) If so, who will be pulling them, and how much will it cost. City/County fees vary, but the labor fees for installers to pull permits is usually an hourly rate. In my experience it usually doesn’t go over $300, unless you have to get a special sign variance.
• Installation of the LED Sign: Where will it be going, how high, how many faces, etc...
• Electrical Connection: Most installers will make the final connection to existing power within 5 ft of the sign, as long at there is no digging involved. Make sure this is clear.
• Terms: Layout your expected terms in the quote request. Common terms are 50% down payment, and 50% after the installation is completed.

Once you get the quotes back, take note of the following items:

• Is the price reasonable? Getting more than one quote will help you determine this. If you get (4) quotes back for $2000 and (1) quote back for $600 chances are the low price is either because the installer isn’t quoting the entire scope, or they are under quoting to secure the job, and will increase the cost during or after the installation. The key is to get as many reasonable quotes as possible, to help you get a feel for the “Market Price”.

• How quickly did they get it back to you? Most of the time a 1-2 day turnaround is good. If the quote comes back to quickly, verify that the installer is actually quoting all the work and not just throwing a cheap price out there. If it takes too long, you may want to avoid that particular installer. They might be overly busy, or under organized.

• Does the quote include the entire scope in your original quote request? Double check your quote and make sure you are comparing apples to apples between the quotes.

When securing the final installer, make sure the agreement and scope are very clear. I commonly use the phrase “if it’s not in writing, it doesn’t exist” when talking about any kind of service or agreement between two parties. Make sure you have a clear and complete quote and/or agreement for any installation. Email is useful here, and can serve as a good place to verify and keep pertinent information available.

- Scott Hofheins


* I welcome ALL constructive comments. Please feel free to comment and add anything I’ve missed, or additional tips you may have regarding this topic. Please visit www.vantageled.com for any other resources, white papers, and of course: Great looking LED Signs!

**All posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

Is your Digital Signage creating a call to action?

-Deacon Wardlow

Oil change $19.99. Bottomless cup of coffee: $0.99! Sale! Town Hall meeting: 7pm. A lot of Digital Signage is failing the target audience. We push out information without considering the medium nor the end-result. Digital Signage is dynamic, alive, changeable and still unique enough to be eye-catching for even the most mundane of messages (time and temperature).

Without a call to action, Digital Signage falls flat. What is the reason for the target audience to do anything other than forget your message when they’ve passed by the display? Regardless of the medium (LED Sign, LCD, DLP, etc.) content which lacks a call to action fails.

A call to action doesn’t have to be a clarion call to the masses. Simply adding a small touch, a few words to something changes the nature of the message and makes it more appealing to the audience:

OLD: Oil Change $19.99
New: Meet Bubba, have a cup of coffee & an Oil Change, all for $19.99

OLD: Coffee: $0.99!
NEW: Free coffee with cup rental: $0.99!

OLD: Town hall meeting: 7pm
NEW: Be heard and be a part of the community, Town Hall Meeting @ 7pm!

The call to action is often lacking and this underutilizes a valuable resource for communication to your audience. A monologue (Coffee: $0.99) becomes an intriguing message which potentially leads to a stop-in (Free coffee with cup rental: $0.99!). Having your audience connect with you draws them in, makes your message more memorable, more effective, and your signage becomes dynamic.

Put a special on (i.e. free drink for the best joke emailed to: _____@email.com), give people something in return for their taking the time to stop in or do something. Put up messages with no other purpose than to make someone smile (give a person a smile and they’ll remember you and come looking for more).

The next time you’re putting together a message, ask yourself if it contains a call to action. If it doesn’t, step back and see how it can be modified to turn the monologue into a dialogue. You have the opportunity to start a great conversation, make it happen today!

*I invite you to comment here and/or email me directly with requests at deacon@vantageled.com. Vantage LED has white paper resources and more educational material on the website (http://www.vantageled.com), please check it out when you have a moment. Note all posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

National Electrical Code Compliance and YOU!

- Mike Prongue

    
My dear wife, a former fire inspector and fire fighter once attempted to share “sage advice” with me regarding fire codes with the statement “behind every fire code is a tragedy”. Government regulation, regardless of an individual’s political opinion, has at its core the intention to help further and validate an industry and more importantly, in the case of safety regulation - to save lives.

The Electronic Message Center (EMC) industry, Digital Sign Industry, is not exempt from this regulation and most business owners familiar with these requirement look toward the National Electrical Code (NEC) particularly Section 600, for guidance and conformance. Like any regulation there are ambiguities regarding the NEC but EMCs are required to be inspected to NRTL (Nationally Recognized Testing Laboratory) standards. That is clear.

In the early development of the NEC, the term UL, for Underwriters Laboratory, was used in lieu of today’s reference of  "NRTL". Many UL equivalent organizations have come to the forefront since OSHA changed its terminology to reflect it’s choice of “NRTL” in 1988, a few examples are: MET, CSA, NSF, TUV, ETL (Intertek) and others.

Regardless of the NRTL chosen to inspect and approve the EMC at the factory, this inspection has to occur and the inspection is to the same standards regardless of the NRTL used.

When a code inspector signs off on an installation, a NRTL certification listing label number is the permission required for him to not open up the display and inspect the components contained therein.  Without this certification listing the local code enforcement body can ask that the EMC be removed.  Some sign companies lean heavily on the NRTL certification of the power supplies alone, to convince the inspector that the EMC conforms to the NEC. This is bypassing the intent of the NEC and opens the sign company up to liability if damage, injury or death were to occur as a result of a faulty EMC product.

In addition to false claims by sign companies engaged in the actual installation, many overseas manufacturers are quite liberal with use of the NRTL certification label. Displaying a UL certification label (for example) on a website could cause the reader to think the total EMC is UL certified rather than just subcomponents such as a power supply. This is not the same as the completed, total EMC assembly having a UL certification. The same non-compliance penalty exists regarding removing the EMC from the structure after installation due to non-compliance of the certification requirement.

Many documented issues exist regarding EMCs produced offshore and their claim to be NRTL approved- ETL, MET or others.  If it does not have a NRTL certification listing label number issued by the manufacturer, the EMC project should be suspect. If it does have a listing label number and the sign dealer wants to be sure it is legitimate, every NRTL has a toll-free line to validate the certificate.  Many offshore produced EMC units have the claim to be NRTL certified but investigation of this claim will prove that only subcomponents have been inspected to NEC standards.

Also, with regards to offshore produced EMCs, this writer has been told by many company representatives that the EMC model submitted for NRTL inspection bears little resemblance to the EMC models eventually delivered to the USA. The components offered for inspection are top-grade, the electrical connections and wiring are to standard, and installation has been completed with meticulous detail. This sets up a NRTL quandary similar to the magician’s trick of “three cups and a pea”. What cup is the NRTL certification under?

It’s the responsibility of the sign dealer to make sure their product meets the standards of the National Electrical Code.  You get what YOU inspect.

**Note all posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

LED Signs and Free Speech

I read an article last week (read here) about a church in Virginia who was cited by the county government for changing their LED sign more than twice in 24 hours. The church was apparently unaware of this particular restriction and tried to work with the county on a compromise. Unfortunately they couldn’t reach an agreement so the church is now suing the county saying that the law restricts their free speech and free exercise of religion.

I agree with the church, and not just because I work in the LED sign industry. I believe super restrictive sign codes are wrong in general. Signs are usually the first communication that organizations have with the local community. LED signs have taken this communication to the next level, allowing clear and specific messages to be given. This country was built on free speech, free exercise of religion, entrepreneurship, and hard work. I believe overly restricting the ability of organizations to communicate goes against these principles. That being said, I understand the need to make sure we don’t have giant digital billboards shining into a residential area.

Reasonable restrictions and guidelines are necessary, but limiting message changes to only two per 24 hours is going too far and might be overreaction by the county, worried about turning the area into a mini Las Vegas. This “Las Vegas”  fear has its roots in the fact that LED signs are still relatively new to the commercial market. In the beginning, only organizations with deep pockets (like casinos) could afford the full color high quality signs.  Additionally, these new LED signs were purchased not just to communicate, but to be an attraction on their own, seeing who could make the biggest and fanciest sign on the strip.
LED signs are much more affordable, and are now used regularly for churches, businesses, schools and other smaller organizations. Unfortunately, the old idea of an LED sign’s purpose continues to affect sign codes across the country today. This story has received more coverage than normal, but it is by no means an uncommon situation. I have personally been involved with a number of these type of situations across the country and they can be extremely frustrating for the organization involved, who in most cases just wants to replace old technology and better communicate to the public.

I am glad to see this church fighting for their free speech rights, and that this story has received national press. It will be interesting to see how it turns out. The county has already backed off from there original stance (see update here), and many local officials have agreed with the churches position. Supervisor Pat S. Herrity (R-Springfield) is quoted in the updated article saying “This is what happens when you’re not careful with regulation.” Hopefully this inspires other organizations facing similar issues to stand their ground and work with the local government for more reasonable sign codes.

LED signs are the future, they will be around for a long time. Rejecting them in the sign code is  like rejecting the car because it goes faster than a horse and buggy. Obviously, this is the wrong way to approach the situation. Speed limits are put in place, better roads are built, stoplights are utilized and fair traffic laws are developed. This same level headed approach should be taken with LED signs. Fair regulations will promote a higher quality product and safer installations that benefit the public, organizations, and the industry in general.

- Scott Hofheins. 

I hope this post has been informative and helpful. As usual, I welcome ALL constructive comments. Please feel free to comment and add anything I’ve missed, or additional tips you may have regarding this topic. Please visit www.vantageled.com for many other resources, white papers, and of course: Great looking LED Signs!

**All posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

Electrical Safety Certification Marks explained: NEC/OSHA/NRTLs and more...

-Deacon Wardlow

I often come across the question of what an acceptable Certified Mark is for UL compliance. Unfortunately, there’s a lot of confusion as to what an NRTL is, what the code requires and such. So here’s some quick clarification:

Specific Information on the 2011 NEC (National Electric Code) requirements:

The National Electrical Code (NEC) – or NFPA 70 – was updated in 2011, as part of its 3-year change cycle.  The NEC is published by the National Fire Protection Association (NFPA), and is commonly adopted by U.S. state or local political subdivision, and enforced by the Authority Having Jurisdiction (AHJ).

Many NEC requirements refer to “listed” or “labeled” devices, as defined in Article 100 of the NEC. The NRTL (Nationally Recognized Testing Laboratories) program accredits those organizations that, by whose labeling, the manufacturer indicates compliance with appropriate standards or performance in a specified manner.

What is an NRTL?

A Nationally Recognized Testing Laboratory (NRTL) is an independent laboratory recognized by the Occupational Safety and Health Administration (OSHA) to test products to the specifications of applicable product safety standards – such as those from Underwriters Laboratories (UL) and other standards-writing bodies. An NRTL's function is to provide an independent evaluation, testing, and certification of any electrically operated or gas- and oil-fired product. Intertek is recognized as an NRTL in the United States.

What’s the difference between the UL, CSA, and ETL/other Listed Marks?

All the marks demonstrates the product has met the minimum requirements of widely accepted product safety standards as determined through the independent testing of a Nationally Recognized Testing Laboratory (NRTL). As part of that testing regimen, the product manufacturer has agreed to periodic follow-up inspections to verify continued compliance.

Aren’t manufacturers required to use UL for their compliance testing? Isn’t this mandated by the standards themselves?

The simple answer to both questions is "no." In fact, this misconception has misled many manufacturers, distributors, contractors and end-users to believe that UL must be used as the third-party testing partner. To satisfy the prerequisite of having your products tested by an independent organization, the true legal requirement is that the laboratory that performs the testing be a Nationally Recognized Testing Laboratory (NRTL) recognized by OSHA.

Some Useful Links:

OSHA recognizes four organizations to develop product safety:

1.    ANSI
2.    ASTM
3.    UL
4.    FM

Standards from the four are approved for use by ANY of the NRTLs OSHA lists/recognizes to test and certify products.

OSHA’s listing of NRTLs (Nationally Recognized Testing Laboratories)

http://www.osha.gov/dts/otpca/nrtl/

UL has both a standards development group AND a testing group. The landmark case which MET instigated in the 80s made it so UL no longer had a monopoly and other companies were allowed to be listed as NRTLs.

For further reference, please check the following websites:

OSHA article on NRTLs Approval of Products:
http://www.osha.gov/dts/otpca/nrtl/NRTLarticle.html

More on NRTL and legal use:

Under the Occupational Safety and Health Administration (OSHA) Act of 1970, OSHA uses Federal regulation Title 29 of the Code of Federal Regulations, Paragraph 1910.303, Subpart S (29CFR 1910.303 (S)), which requires that all conductors and equipment are approved (listed), it also requires electrical equipment to be examined, to ensure it is free of hazards likely to cause harm to employees and be suitable for installation (by listing or labeling).

In addition to OSHA requirements, which cover only the workplace, the USA relies on local building codes to ensure safe residential housing. These codes are based on the requirements of the National Fire Protection Agency, standard NFPA 70, also known as the National Electrical Code (NEC). This code is adopted universally by state and local inspectors who are empowered by their authority having jurisdiction (AHJ).

Some common AHJ (Authorities Having Jurisdiction) personnel known for their strict enforcement of local electrical codes include the City of Los Angeles, the City of Chicago, the State of North Carolina, the State of Oregon, the State of Florida, the City of Orlando and New York City. In these locations' electrical inspectors "red-tag" electrical products that are not listed or labeled. The legal requirement for acceptability to the local AHJ is derived from Article 110 - Requirements for Electrical Installations. As a result, electrical inspectors will look for an NRTL listing, or a field label

The NEC code 800-4 additionally requires all equipment connected to a telecommunication networks to be listed. If equipment is not listed or labeled a supplier may be asked to pay for it to be field labeled on site before it is released for use, and lose a potential repeat order from the customer, due to the delays involved. In addition, AHJ inspectors who are IAEI members exchange information on manufacturers who they know are noncompliant.

Source: http://www.engineeringtalk.com/news/tvi/tvi102.html

Make sure the manufacturer/reseller you’re dealing with knows the code and is 100% compliant. A failure on their part can cost you and your business money, reputation and more.

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