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Navigating the Jungle of U.S. Industrial Standards

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Different countries have different customs. What seems reasonably exotic to us as Europeans is normal for other nations.

For example, the difference between Listed (UL) and Recognized (UR) components. To prevent any misunderstandings, I will provide you with a quick guide through the American "jungle of standards."

OK, I admit it: As a company with headquarters in the U.S., we have a home advantage. My colleagues in America are sitting right at the source. They are well informed and help us navigate the industrial standards in America.

And the use of the expression "jungle" is justified in this context: The world of applicable standards in the United States is in fact fairly dense, may appear to be tropical for those new to IEC, and is therefore not at all easy to see through. But the good news is – is that it is possible.

And we are happy to help you do it – right here, right now – with a quick but comprehensive guide to everything you need to take into consideration when joining the market in the United States:

The "Big Three" Provide a General Overview

With regard to your machinery or control panel equipment, you must keep in mind the following as the basis for everything to do with electrical equipment: UL508A (for control panels with a voltage of up to 600 V in normal environmental conditions), NFPA 79 (for industrial machines) and the National Electric Code (NEC).

There are Exceptions to Every Rule

This also applies here. Hence why there may be various additional requirements in the State Building Codes of the individual federal states.

It is especially important to check this where large new systems are involved. Generally speaking, the customer knows best what circumstances need to be taken into account locally.

The American National Standards Institute (ANSI), the National Electrical Manufacturers Association (NEMA) and/or the Occupational Safety and Health Administration (OSHA) also still have a decisive say on a number of topics.

Consideration Company Regulations

In large companies in particular, meticulous compliance with the company regulations (e.g. wire colors and core marking) is a top priority.

It is therefore better to make inquiries in advance rather than suffer during factory acceptance testing or be subject to the obligation to make subsequent modifications.

Plan in a Buffer During Commissioning

Since the laws, and sometimes also the practices, are different in the United States, newcomers to the American market should have a good "guide" to who is very familiar with the local circumstances, and they should factor in a little more time than normal for installation and commissioning on site.

It is generally highly beneficial to collaborate with a system integrator at the relevant site who knows the local requirements and has the relevant concessions – especially when installing the system and putting it into operation.

If in Doubt, UL Listing Simplifies Machine Builder Effort

The UL/UR marks of Underwriter Laboratories are very important in the United States.

It is much easier for a machine builder to incorporate a UL Listed component into their system. A UL Listing mark on a device or system helps ensure that the products will comply with the standards and regulations in the U.S.

When marked only as "Recognized," the machine builder should be aware that the product meets UL recognition requirements, but this specific configuration has not necessarily been tested by UL.

Finally, another hot tip on the topic of UL certification: In this context, if at all possible, be sure to keep in mind the motto "If it ain't broke, don't fix it."

At the end of the day, changing a tried and tested solution that has already been accepted by the Underwriter Laboratories could cost you dearly – and lead to numerous discussions or sometimes even new examinations.

The same applies to what appear to be mere trivialities, such as a simple name change for a product combination that has already been listed.

A Land of Virtually Unlimited Voltage Options

America is largely a neutral conductor-free zone. This means that nothing enters the power supply in the country without pole transformers.

And there are a large variety of voltages available for this: Everything is possible, from 120, 240, 480/460 up to 600/575 V, whereby the 480/460 version is the most commonly used.

However, nothing is fixed. This is why the key data must be clarified for every project, e.g. how much voltage, which grounding method, which network.

With grounding measures in particular, you may be in for a nasty surprise, and in the area of engineering, failures lead to fatal errors and additional costs.

Just One More Thing

Short Circuit Current Ratings (SCCR) are an absolute must in the United States. The ability of switchboards to resist a short circuit must be determined mathematically and specified on the rating plate.

Alois Marks
Alois Marks
Technology Consultant, Rockwell Automation
Alois Marks ist Technology Consultant in Linz ist seit über 33 Jahren Ansprechpartner für Kunden von Rockwell Automation rund um Fragen zum Schaltschrankbau nach nordamerikanischen Standards.

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