Electrical Theory Confusion

[DBoone]

I am relatively new to residential building and electrical (4 yrs), but I have not had any problems finding good information to study electrical theory. I have learned a lot thru this forum as a matter of fact.

Any ideas on why so many people are misinformed on electrical theory today? (electricity goes to the ground, follows only the path of least resistance, "neutral" and EGC are basically the same since "they go to the same place", etc.

 

[zbang]

Any ideas on why so many people are misinformed on electrical theory today? (electricity goes to the ground, follows only the path of least resistance, "neutral" and EGC are basically the same since "they go to the same place", etc.

Probably two things. First, science education was either dumbed down or just removed from the school curriculum years ago. The students never had a chance to learn the theory (like putting two light bulbs in parallel, they both light up). That covers those newer to the trade. For the older ones that might have had the benefit of that education, I suspect that many of them just ignored it, and when they went into the trade, the ideas and training were different so they never learned.

That's all a monday-morning guess.

 

[cadpoint]

You need to carry the ugly book or other pocket references to show to associates when they state
odd things.

Here's one I like to use.

If one drew out a single line diagram of a simple switched lamp circuit it being eiither A/C or D/C the only change of terms in what the single line is called after the lamp element! A neutral if a A/C and if a D/C circuit a ground.

Use the simgle line, watch for the oh moment. Go on to state that a complete circuit is required and with A/C it
wants to return to source and D/C needs the same thing, a path to a source of power that in D/C happens to be
a lot of times a self contanted power source.

Proceed at will with enlightment of the masses, it'll be like anything else so have selective listening some will
not be receptive. Good luck with the associates.

 

[K8MHZ]

I am relatively new to residential building and electrical (4 yrs), but I have not had any problems finding good information to study electrical theory. I have learned a lot thru this forum as a matter of fact.

Any ideas on why so many people are misinformed on electrical theory today? (electricity goes to the ground, follows only the path of least resistance, "neutral" and EGC are basically the same since "they go to the same place", etc.

Are you speaking of laypersons or electricians?

As for people not in our trade, the simple fact is that the things you speak of weren't taught in standard high school classes. Learning Ohm's Law does not explain how a premises electrical system functions and why there is a grounding conductor present.

I teach ham radio classes from time to time. There are many myths circulating about safe radio operations just like there are about basic electricity. One such myth is that it is good practice to disconnect your antenna lead and place the end in an empty glass for protection from lightning damage.

I don't think there are any more misinformed people now than there were decades ago. Just think about some of the messes in old wiring encountered that were done 40 or 50 years ago.

I can also tell you one thing about electrical theory. If you study it on an ongoing basis, you will learn that what you think you know now may not encompass all the facts.

For instance, when you think of a complete circuit being needed for current to flow, how do you explain current flowing in a dipole antenna? Enough to light up a string of Christmas tree lights. No apparent complete circuit, just two conductors with no (obvious) connection at all.

When most of us think about opposition to current flow, we think in terms of resistance, capacitance and inductance. What of radiation resistance and reverse EMF? We learned about REMF in the apprenticeship, but nothing of radiation resistance. How many sparkies are familiar with reluctance and acceptance? And what of conductance? Were you taught anything about mhos or seimens?

And what of the myths perpetuated by the teachers? We had an excellent teacher that was stuck on the myth that there were two phases in a single phase 120/240 volt residential system. That argument has taken place on this forum with literally hundreds of posts both for and against the assertation.

Much of this depends on your perspective. As an electrician what you see as obvious may be misunderstood by a layperson making you think they are misinformed. As an extra class amateur radio operator having been exposed to many nuances of electrical theory not taught to electricians, I often feel that electricians (and sometimes EE's) are misinformed. And in fact, when it comes to lightning protection, many are misinformed and dangerously so. What applies to a premises wiring system changes immensely when there is a 70 or 80 foot metal tower supporting an antenna connected to a radio supplied by said premises wiring.

I think it's the complexity of electricity's behaviour that makes it so difficult to understand for most, yet makes it so fascinating for a few.

 

[DBoone]

Are you speaking of laypersons or electricians?

As for people not in our trade, the simple fact is that the things you speak of weren't taught in standard high school classes. Learning Ohm's Law does not explain how a premises electrical system functions and why there is a grounding conductor present.

I teach ham radio classes from time to time. There are many myths circulating about safe radio operations just like there are about basic electricity. One such myth is that it is good practice to disconnect your antenna lead and place the end in an empty glass for protection from lightning damage.

I don't think there are any more misinformed people now than there were decades ago. Just think about some of the messes in old wiring encountered that were done 40 or 50 years ago.

I can also tell you one thing about electrical theory. If you study it on an ongoing basis, you will learn that what you think you know now may not encompass all the facts.

For instance, when you think of a complete circuit being needed for current to flow, how do you explain current flowing in a dipole antenna? Enough to light up a string of Christmas tree lights. No apparent complete circuit, just two conductors with no (obvious) connection at all.

When most of us think about opposition to current flow, we think in terms of resistance, capacitance and inductance. What of radiation resistance and reverse EMF? We learned about REMF in the apprenticeship, but nothing of radiation resistance. How many sparkies are familiar with reluctance and acceptance? And what of conductance? Were you taught anything about mhos or seimens?

And what of the myths perpetuated by the teachers? We had an excellent teacher that was stuck on the myth that there were two phases in a single phase 120/240 volt residential system. That argument has taken place on this forum with literally hundreds of posts both for and against the assertation.

Much of this depends on your perspective. As an electrician what you see as obvious may be misunderstood by a layperson making you think they are misinformed. As an extra class amateur radio operator having been exposed to many nuances of electrical theory not taught to electricians, I often feel that electricians (and sometimes EE's) are misinformed. And in fact, when it comes to lightning protection, many are misinformed and dangerously so. What applies to a premises wiring system changes immensely when there is a 70 or 80 foot metal tower supporting an antenna connected to a radio supplied by said premises wiring.

I think it's the complexity of electricity's behaviour that makes it so difficult to understand for most, yet makes it so fascinating for a few.

One thing I've learned is I have only just begun to scratch the surface of understanding electrical theory. Just when I begin to think I'm getting pretty good I get humbled quickly and realize I don't know very much yet after all.



I confess I only study electrical theory and installation as it applies to 120/240v single phase systems because that is what I deal with in my job.

 

[ggunn]

One thing I've learned is I have only just begun to scratch the surface of understanding electrical theory. Just when I begin to think I'm getting pretty good I get humbled quickly and realize I don't know very much yet after all.

Me, too, and a lot of times it's OW! Why did that happen?

 

[Besoeker]

One thing I've learned is I have only just begun to scratch the surface of understanding electrical theory. Just when I begin to think I'm getting pretty good I get humbled quickly and realize I don't know very much yet after all.

That's a big step in my opinion.
The beginning of understanding is the acknowledgement of ignorance.
I think that's paraphrased from Socrates.

 

[junkhound]

ideas on why so many people are misinformed on electrical theory .QUOTE]

Hmm, good question..... have been designing power and power systems for over 50 years, everything from B&W TVs to spacecraft and airplanes, and still am learning things.

Most of the misinformation I run across is by folks who have never seen 'happenings' first hand, who just regurgitate what someone has said or read in a textbook. Seeing stuff happen is when you may understand and usually remember.

Example: 50 kVA Delta-Y xfmr in office building operated just fine for decades, inspections showed no degradation. One day it just up and burns out, severe overheat, but measured load on new transformer (100kVA) showed only 23 kW. Wazzup?? Company had recently upgraded desktop computers. Investigation showed every desktop now had a 12 Vdc power supply with full wave bridge feeding big 800 uF capacitor, PFC chips were still almost a decade away.


Learned good that week about triplett harmonics generated by bridge rectifiers and the delta primary being a short circuit for the harmonics, big time overheat. Many folks probably never even consider PF let alone harmonics.

 

[GoldDigger]

Example: 50 kVA Delta-Y xfmr in office building operated just fine for decades, inspections showed no degradation. One day it just up and burns out, severe overheat, but measured load on new transformer (100kVA) showed only 23 kW. Wazzup?? Company had recently upgraded desktop computers. Investigation showed every desktop now had a 12 Vdc power supply with full wave bridge feeding big 800 uF capacitor, PFC chips were still almost a decade away.


Learned good that week about triplett harmonics generated by bridge rectifiers and the delta primary being a short circuit for the harmonics, big time overheat. Many folks probably never even consider PF let alone harmonics.

What was your long term solution? Just keeping the oversize transformer or more specific corrective action?

 

[junkhound]

Just keeping the oversized xfmr. Learned that since the 19th century delta-Y oversizing has been a common triplet harmonic remedy. The advent of the single core 3 phase transformers resulted in triplett harmonics due to slight flux imbalance (much less than rectifiers though) and most early 3 phase single core transformers were designed with oversized primary winding simply to dissipate the harmonics.

In the 1990s, the EU instituted a bunch of regulations that limit PF and harmonics on electrical and electronic equipment. Once the windmills and solar inverters are more than 10% of grid support here, expect to see similar regulations in USA. http://www.eetimes.com/document.asp?doc_id=1272376

 

[rt66electric]

1920' hawkins books

1920' hawkins books

I have read some 1920's "hawkins electrical guide"

There is a complete line of books similar to a "Machinist handbook"

from plumbing to shipbuilding.

The books are amazing. Everything an electrician needs to know is in there( including kn+T wiring methods) I have learned more from the OLD books as compared to any instructor in college,or trade school. Most everything was invented before 1920, and alot has been forgotten, ( electronics is a new thing 1960's ,just getting smaller and faster)

I have had RLC theory and such and more in electronics engineering, but the instructors could not come up with a real world example as how use it in action.

 

[DBoone]

Me, too, and a lot of times it's OW! Why did that happen?

Glad to know I'm not alone. PS - I've been at my current job for 3.5 yrs, not 4.

 

[K8MHZ]

I have read some 1920's "hawkins electrical guide"

There is a complete line of books similar to a "Machinist handbook"

from plumbing to shipbuilding.

The books are amazing. Everything an electrician needs to know is in there( including kn+T wiring methods) I have learned more from the OLD books as compared to any instructor in college,or trade school. Most everything was invented before 1920, and alot has been forgotten, ( electronics is a new thing 1960's ,just getting smaller and faster)

I have had RLC theory and such and more in electronics engineering, but the instructors could not come up with a real world example as how use it in action.

Well, I would think that PF correction would be a real world example. Also antenna design. Antennas can be made shorter by using loading coils. Traps made of coils are used in multi-band antennas. Many high end TV antennas have trimmer capacitors in them. My Winegard does.

I do not agree about most everything being invented before 1920. How many solid state devices were invented before 1920?

Many tubes were invented after 1920. For the pentode, it was 1926. Power beam tubes, like the 6L6, did not come out until the 30's. Same for most multi-function tubes.

The first modern circuit breaker was patented in 1924.

Most of the insulation we use today is of relatively modern origin. What was it in 1920, shellac, paper and gum arabic? NM was first listed in 1926.

Plastic tape wasn't around until the 1940's.

As for wire nuts, the porcelain ones came about shortly after 1920 and the bakelite ones, 1930. Plastic ones came out in the early 60's.

And on and on. The fact is, most of the stuff we use today was invented after 1920.

 

[kwired]

This is not the only trade like that. There are many out there that think just because they can make something "work" that they are experts in the application, yet they don't really know how or why it works the way it does. There are times when those people run into a problem and just throw parts at it until it works, where a true expert finds the problem based on theory and logic, and usually finds the right problem the first time.

 

[GoldDigger]

This is not the only trade like that. There are many out there that think just because they can make something "work" that they are experts in the application, yet they don't really know how or why it works the way it does. There are times when those people run into a problem and just throw parts at it until it works, where a true expert finds the problem based on theory and logic, and usually finds the right problem the first time.

Old computer geek joke from the days of Digital Equipment Corporation:
"How many DEC field service engineers does it take to change a flat tire?"


"Five. That's four to lift up the car and one to swap tires until he finds the one that's flat."

 

[Conrad]

One thing I've learned is I have only just begun to scratch the surface of understanding electrical theory. Just when I begin to think I'm getting pretty good I get humbled quickly and realize I don't know very much yet after all.


I like the saying "Its what you learn after you learn it all that counts"

I served a 4 yr App Program, actually 5. I changed companies and started with a new program back at first year again.

Much of the theory I learned will never get used, the understanding it gave me gets used everyday. I now like to play in electronics and such, the theory is still there, I just have to think real hard. But just like basic electrical, integrated circuits still work because they contain "magic smoke". When the magic smoke leaks out, they stop working.

Anybody else working on a synchronized Christmas light display this year?

 

[ggunn]

Much of the theory I learned will never get used, the understanding it gave me gets used everyday.

That means you use the theory you learned every day. The purpose of studying theory is to develop the intuition you use when you confront a problem in the real world.

 

[kwired]

One thing I've learned is I have only just begun to scratch the surface of understanding electrical theory. Just when I begin to think I'm getting pretty good I get humbled quickly and realize I don't know very much yet after all.


I like the saying "Its what you learn after you learn it all that counts"

I served a 4 yr App Program, actually 5. I changed companies and started with a new program back at first year again.

Much of the theory I learned will never get used, the understanding it gave me gets used everyday. I now like to play in electronics and such, the theory is still there, I just have to think real hard. But just like basic electrical, integrated circuits still work because they contain "magic smoke". When the magic smoke leaks out, they stop working.

Anybody else working on a synchronized Christmas light display this year?

You may not use all the theory you learned everyday, but if you stop and think about it you probably use more of what you learned than you realize on a pretty regular basis, if you are involved with electrical work of any kind on a regular basis.

What many people call basic electricity 101 or something similar is the foundation of all electrical trades, from power and lighting to electronics, to high voltage distribution, they all learn Ohm's law, Kirchoff's laws, many basic definitions that are the same through all electrical applications, etc. If you understand why the magic smoke leaked out, you have applied some of that theory to come up with that understanding.