How much electrical theory should a first year apprentice know?
Not so much on the job stuff but classroom work. Now that I am in a teaching post I am having to re-learn a lot of stuff. Stuff that I just took for granted whilst on the tools (never looked at once on the tools more like, or just did without thinking about it)
I have been asked to look at the units I teach with a view to improving them. Ohms law , Kirchofs law, series and parralel circits are quite staight foward. But the only way I see of taking these units froward is to introduce more AC theory. Is it usefull to know how to calculate RMS, peak and average voltages,complex numbers, phase angles and the like? Shurely only a systems designer is concened about these calculations? Or do you use them out in the field?????
from a contractors perspective, save the theory for a bit. 1st half of 1st year should be practical. Nothing fancy, just wire sizes and ampacitys (upto #8 or so) basic principals of distribution, some notion of different receptacles and what they are for.
I say this, because we hire 1st yrs who don't know the basics, so we have to spend time teaching them. costing the contractor money. But at the same time they are getting seriously confused by all the theory that they are learning in school.
once we spend 6-8 months teaching them the basics everyday, then they seem to grasp the theory better.
it's a tough call, and this is just from my experience.
Beyond the basic physics of how many amperes you can stuff into a given size wire, one of the basic tools that apprentices can utilize early on is transformer thoery. Perhaps an overview of the Tesla System, briefly how it is made, distributed and down to the level that we work on every day, how the basic 120/240 voltage is derived, 120/208 and 277/480, but start with a basic doorbell circuit and turns ratio=voltage ratio stuff. Kirchoff's Laws are a bit esoteric for a beginner, they can't relate, whereas the question of how come a house has x voltage between this drill case and the water pipe I just grabbed is something every greenhorn can relate to.
Ohm and Kirchoff are important but mostly from the overview aspect. Ohm says the current is dependent of voltage and resistance, an important concept to understand. Kirchoff says if the current went in there it is all coming out somewhere, also important.
As far as school goes, I got just basics when I started out. I learned quickly in the US Navy and parlayed what I learned there into wiring new homes. Out in the field nobody teached me any theory. Somehow I managed to survive and before too long I was wiring all sorts of things including services.
I'm in school now learning all about theory and I have a new found confidence in the workplace because of it. I should've done this 10 years ago!!!
As fas as being out in the field, I am teaching a 1st year guy who knew nothing 6 months ago. One of the first things I taught him was how to avoid being shocked. That means never working live unless you really have to. But he understands about becoming "part of the path" and the measure that need to be taken to avoid accidential shock. He can cut-in and wire receptacles, single pole switches, sometimes even 3-ways, and understands the importance of using GFCI protection on construction sites.
[This message has been edited by ShockMe77 (edited 10-09-2006).]
While theory is fine - and I certainly appreciate the need to understand why you need to do things a certain way- I fear that we have a tendency to give too much theory too soon.
I think that first you need to learn what gets done. Then you learn how to do it. THEN you learn the 'why.' When all this is covered, then you can begin to tinker with things, try to apply what you've learned.
Instead, I have been in far too many coures where they started off with theory. Ask "how," and the response was "you can figure it out."
Even in our trade, I have encountered far too many who spoke knowingly of "harmonics" - folks who had never seen an amp clamp. had no idea how to use one, or any clue as to how to identify / eliminate harmonics as the problem. To me, this is a sign of when "education" has exceeded "learning."
One aspect that complicates things is that many come to the trade having already been mis-educated by their prior jobs. I suspect that most of the first year is spent 'un-learning' bad habits.
I would say a mixture of both for the first years. Therory in itself wont tell you how to actually put it together, but all the machnical ability in the world wont give you a clue to how it actually works. I would say a delicate balance of hands on, and know how and know why. If you hold off all the book work, it will never get done, but if you drown them in it, they are useless for a few years in the field.
Is the book end of it usefull? - darned straight it is! If you have no understanding of therory, you are essentially a Parrot - mimicing what you have little understanding of. Doing what you are told.... You might be able to connect 2 wires together but not be able to understand how or why to fix something, and will have a really hard time troubleshooting later, if at all. And all circuit design is in the field. No one has ever handed me a schematic or line drawing of any use.
Conversely, I learned therory, and was trained to troubleshoot before I got out of the classroom. I could troubleshoot generators from the engine through the voltage regulator and through just about any 3-phase motor control you threw at me. But ask me to actually install something and I was clueless.
The "laws" are useless without therory, and practical application can be a life of robot work without a fuller backround of understanding.
However, therory at this level does not need to be complicated. It can be summed up in some simple anaolgies. It doesn't need to broken down to the atomic level to gain an understanding of Ohm's law, or visualizing a sine wave, or understand the difference between AC or DC. The Firehose, Ping-pong ball, Billiard ball or Pachinko game anology would work fine for the purpose.
Mark Heller "Well - I oughta....." -Jackie Gleason