With that being said, one of the things I want to bring as far as important part of the National Electrical Code is that it is an evolving document, as I mentioned earlier. And the reason for that is because our understanding of the science of how electricity works is still evolving, and anyone who's been in the industry for longer than 20,30 years has definitely know seeing the many changes that have happened over the last...you know, since the National Electrical Code first came out, and that's one of the reasons why this is an evolving document. And in support of this document, one of the things, if you have a National Electrical Code book that you have and we cover this our class too as you look in the front of it, and you will notice all the contributors to all the boards that sat there and pay attention to the roles that each of those members played when making the rules and the regulations as you find at the National Electrical Code. And you will notice that most of them are bonafide engineers, scientists, those who apply the scientific method for this.
In popular contrary to belief, the National Electric Code and also the entire NFPA series does make an effort to try to not make this politicized or driven by profit. That is a common misconception on when you new rules came out. So, someone is trying to make profit. So sometimes I can agree with you that it is the case, but overall, the whole NFPA series is designed to be an enforcement tool, and also to give a standard which all manufacturers, those of us who are technicians, construction persons, that way we have a standard to follow and that we can make things more safe and so we don't burn buildings down and get people killed accidentally because of neglect. And that's the purpose of the code is that we follow this code. Even though there are parts of that we don't understand, many of these pieces that are in there were thoroughly researched.
For example, some of the new things that have come up with the code that have evolved in recent time in the last decade is their understanding of art flash. Now, the National Electric Code explains it more generically, that's an NFPA 70, and the more detail in NFPA 70, the electrical portion of it and that's one of the reasons why if you go back, say far back as the 70s, people didn't take art flash nowhere near seriously as we do now, and that's just because the science has evolved considerably since then with the advent of high speed cameras, thermal infrared imaging, vibration analysis, and even the exchange of information with the internet. Much of that has what has led to the changes that we have in the National Electrical Code.
As you can see on the slide here, this is about typical. So, there's over 4,000 public inputs submitted to code in 2014. If several of these boards are put together and much discussions, even the wording is very specific because they want to make sure that the communication to the readers is as clear and precise as possible. Many of these are written with that in mind and so, they try to choose their language that is both easily understandable, broad, but unambiguous, so that it can be properly used. As you can see in 2017, five new articles were introduced.
First, is Article for 425, and this is talking about fixed resistance and of course electrical industrial process heating equipment. Yes, there's already been a lot of code regarding how boilers are set up, and there's even a separate code, and those of you who are boiler techs are really up to speed as far as how strict the code and regulations are for boilers. But as technology boilers themselves have evolved, so has the electronics, the types of equipment used to heat it, to ignite the boiler, and the regulation of it. That has also evolved. And as a result this code was created to augment the already existing code of boilers.
So next is Article 691. It makes pretty much sense because now we're getting that whole green energy thing. And as a result, photovoltaic supply systems, especially on the industrial scale, as you can see here five megawatts and larger, have become predominant enough to ignite the interest and as electric goes and say, "We need to address this. The good news about this is, as many of these standards are much the same, especially those of you who ever worked with large UPS systems, because a lot of times, photovoltaic systems act as both part of the UPS system and also act as, especially those who are also familiar with your if you have code generation because the photovoltaic system, especially large ones, act very well with code generation applications. So, here's an example of some of the larger farms. This is the kind of scale we're talking about, that takes up acres and sometimes, even several hundred thousand square feet on top of one of your large facilities. Kind of put it to scale, this is not referring to the couple panels you have on your roof at your home, but rather than industrialized large scale solar farms.