I think it would be better if they would go to a five-year cycle. Some people think that this means that electrical safety would suffer. I personally don’t think that it means that. If during the five-year development cycle a few safety issues arise that need to be more quickly resolved, states have the power to adopt their own amendments. I actually think it might be better for safety to have a 5 year cycle because instead of going back-and-forth and changing verbiage to supposedly clarify things every three years and creating more confusion in the process they might be able to create a better standard.
If they were on a five-year cycle more people would have experience with implementing the new version before the closing of public input stage due to its having been adopted. This would mean more every day electrical stakeholders having exposure and being more able to submit actually substantiated public inputs. This would make for a better standard. Instead they have this hyper-development schedule where mostly large enterprise (and the retired of course) very many times are involved in what the new code version says because everyone else is busy working and it has not yet been adopted for their work.
I partly agree. NESC (IEEE C2) is one of the few IEEE documents that has a fixed cycle of 5 years. Even after the testing was done it took years for IEEE 1584 to get voted on for final approval. There was nearly 20 years between the 2001 and most recent edition. Similar issues have happened with other standards and even more mundane things like computer software. The best way to avoid stagnation and letting things get bogged down in committees is by having a fixed time table. NFPA has required 3 or 6 years for most of their standards.
The problem right now is two fold. The first is that we have manufacturers sitting on committees voting on whether or not a new product is a good idea. Almost by definition they shouldn’t even be allowed to vote. Similarly we have engineers doing the same thing. If anything it should be obvious that the problem is too many partisans that are able to manipulate the system. This has resulted in many really bad or at least unsubstantiated and expensive ideas creeping into the Code. In my opinion NFPA is creeping ever closer to the point where aggressive AGs are going to dig into them.
Similarly we have a problem over on the engineering side. There has been a battle brewing for years not only with engineering but all trades. Are you seriously telling me you need a special college degree and pass a test and pay a license fee to cut hair? Licensing boards have become far too strong for all professions and it has become nothing but a scam, electricians and engineers included. At one time when things were just getting started the first president of the AIME (what became IEEE) wasn’t even an engineer. At that time AIME and SME (mining engineering) promoted developing standards and promoting education for the public good. Their engineers for the most part worked within various manufacturing and other businesses. The ASCE (civil engineers) on the other hand represented a group that wanted to put themselves up on a pedestal, banning everyone else from practicing engineering (literally doing simple arithmetic or looking things up in tables in many cases). They were all about the money and felt they should be a protected group like doctors and lawyers. And the battle still goes on today. Most recently the NCEES has been heavily pushing efforts to sue anyone and everyone they deem to be doing engineering without a license. Recently for example in Oregon they went after a mathematician because he claimed when they put in red light cameras the traffic engineers purposely adjusted the light timing so fast that it was physically impossible to stop in time. He beat them in court because essentially his crime wasn’t practicing engineering without a license but doing unauthorized arithmetic.
And to some value points, two of the big “gotchas” in terms of required engineering studies are short circuit studies and arc flash studies, and the two go hand in hand. The problem with short circuit isn’t that an average licensed electrician can’t do it. There are lots of seemingly simple methods out there. A basic example is the “infinite bus” method of calculating short circuit on a transformer secondary. The calculation is simply kVAx1000/(Volts x 1.732 if it’s 3 phase or 1 if it’s not) / (%Z/100). You can also include feeders and other things with the point-by-point method published by Cooper-Bussman which truly makes it a simple calculation. But there’s a catch: inductive loads (motors and generators) become SOURCES during a short circuit. This simple calculation misses this fact. For 30 cycle equipment it is less of an issue but with 3 cycle equipment it can be a significant factor. This is where engineering software and knowing how to use it matters. And at that point, might as well just pay the fees. There are some rules of thumb though. If no motors exceed 25 HP you can effectively ignore this (not enough inductance to matter).
Aside from this issue the problem with using the infinite bus calculation is that it is often wildly off and produces very high results. It’s one thing if the calculation says you need 25 kA AIC or even 35 kA. But the price goes way up on 65 or 100 kA equipment. So this is where an engineer can actually reduce costs on a job.
Realistically the ANSI method was developed way back when we used slide rules instead of calculators and spreadsheets. It is easily possible to still do this with a spreadsheet and a little knowledge. Expensive engineering software is convenient but not absolutely necessary.
Second major area is arc flash. This one is much harder to solve. Currently NFPA gives you two options. You can use the tables in 70E but then it has all kinds of “gotcha” clauses about arcing current and trip times that are essentially impossible to answer. Or use the engineering approach which means use IEEE 1584. The current calculation method is not too terrible. It is long, tedious, and needs spreadsheets but it can be done. Aside from some basic equipment data the key problem
Input is the short circuit current. Everything else is fairly straightforward.
But wait, we can just use the infinite bus calculation or ANSI method, right? Well not so fast. With short circuit ratings we don’t care about accuracy as long as we don’t undersize the equipment. If we calculate 20 kA and the real short circuit is say 15 kA that’s not a problem but would be a big problem if it was 25 kA. All the short cuts result in higher short circuit currents. So it works for short circuits.
Logically we would expect that if we overestimate currents for arc flash we just get overestimated arc flash energy. But that’s not what happens. At the first step in the calculation we calculate the arcing current which is essentially a percentage of the short circuit current. Then we look up how fast a fuse or breaker will trip with the known arcjng current. Finally we use these two pieces of information and some others to calculate the thermal energy from the arc. If the short circuit current is overestimated something curious happens. If the breaker trips due to an instantaneous setting then as we would expect, the overestimate results in higher thermal energy. If the arcing current is low enough that the breaker is operating on its thermal (inverse time) curve, if the arcing current is overestimated then the arcing time goes down. BUT the increase in current is not enough to overcome the decrease in time. The result is that the overestimated arcjng thermal energy is underestimated rather than overestimated. Often by a large amount. Thus current practice is to estimate arc flash with the most accurate calculations available. Thus means getting as close to an accurate short circuit result as possible with NO short cuts.
Mind you it can still be done. But as an example all impedances in AC consist of a resistance and a reactance. With larger cables in power distribution (starting around #6-8) the reactance dominates. To simplify things the typical ANSI method simply drops resistance and does all calculations with reactance. So instead of complex numbers we work in simple algebra. Under predicting impedances results in higher short circuit predictions but as I said already this is not a problem for short circuit estimation but is a big problem for arc flash. IEC does similar things. You can still optionally do the full calculation with either method but what engineers call the “ANSI” method is the method designed for slide rules. Most computer programs call the full calculation the “comprehensive” method.
Neither calculation requires an engineer. In fact most engineering firms use apprentice or JW level workers to do the actual work. The engineers just check the results and verify everything. At least they claim to…most engineering studies are chock full of all kinds of errors. I once had a major engineering firm (KBR) tell me I had an arc flash boundary of over 3000 feet, larger than the plant itself. The voltage was high enough the software reverted to a known invalid calculation (Lee method) which the engineer did not understand and just accepted the result. If you saw the price tag (hundreds of thousands) you can understand why we had a very heated meeting with them.
