romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
i was thinking divided impedance's kwired~RJ~
Grounding- What Smart Students and Electrical Engineers Are Really Being Taught
- Thread starter mbrooke
- Start date
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
As mentioned basics are the same, but the vehicle body/chassis is generally composed of high conductive material, where you usually have less conductive material in earth return situation. SWER likely don't work at all if you were using it as one side of a 12 or 24 VDC system, and probably is poor performance for nearly all AC systems between 100 and 1000 volts.In what way is a vehicle body/chassis not electrically equivalent to an SWER system?
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
Another video. I'm going to strongly disagree that earth ground keeps frames cold:
mikeames
Senior Member
- Location
- Gaithersburg MD
- Occupation
- Teacher - Master Electrician - 2017 NEC
He specifically talks about "Earth Ground" and then continues to explain how he misunderstands its use compared to Bonding equipment ground..... bla bla bla
Bottom line. It's too easy to make a video, website, post or distribute information with a with good but not perfect understanding. I get tired of seeing it and getting charged up. Some of us get it. Just look at the posts here. We split hairs and critique every word.
It does make it easier sometimes to grab peoples attention as a teacher. They think they understand until you challenge them on their thinking. Then they realize they misunderstood and they never forget. I use the myth or vague line of "electricity takes the path of least resistance". Just tell people its flat out wrong. Incorrect. Then pause while they sit in silence wondering if your serious. Ask them if while in a grocery store if they only check out with the fastest cashier regardless of how many people are on line or if they evaluate how many people are in each line and disregard cashier speed?
People will organize themselves in grocery lines much like electrons do in parallel. Most current will take the path of least resistance, but not all. The most amount of shoppers will checkout with the fastest cashier, but not all. It will always be worth it to be the first in line with the slowest cashier than the 10th online with the fastest. The balance will be decided based on actual speeds and resistances.
Then people start to think instead of repeat stuff. They also start to ask more questions to understand it more.
Bottom line. It's too easy to make a video, website, post or distribute information with a with good but not perfect understanding. I get tired of seeing it and getting charged up. Some of us get it. Just look at the posts here. We split hairs and critique every word.
It does make it easier sometimes to grab peoples attention as a teacher. They think they understand until you challenge them on their thinking. Then they realize they misunderstood and they never forget. I use the myth or vague line of "electricity takes the path of least resistance". Just tell people its flat out wrong. Incorrect. Then pause while they sit in silence wondering if your serious. Ask them if while in a grocery store if they only check out with the fastest cashier regardless of how many people are on line or if they evaluate how many people are in each line and disregard cashier speed?
People will organize themselves in grocery lines much like electrons do in parallel. Most current will take the path of least resistance, but not all. The most amount of shoppers will checkout with the fastest cashier, but not all. It will always be worth it to be the first in line with the slowest cashier than the 10th online with the fastest. The balance will be decided based on actual speeds and resistances.
Then people start to think instead of repeat stuff. They also start to ask more questions to understand it more.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
I know plumbing is a popular analogy for current flow. To illustrate in that case, I'd tell someone to imagine a tank full of water. At the bottom of the vertical sides, we place 1/2", 1", 2" and 4" outlet pipes. Will the water flow out of only the 4" pipe?
mikeames
Senior Member
- Location
- Gaithersburg MD
- Occupation
- Teacher - Master Electrician - 2017 NEC
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Was "at the bottom" insufficient?Yes, you didn't specify the height of the pipes and the water,
I suppose I could have specified the centerlines of all the outlets be the same distance from the bottom of the tank, but as a general thought experiment, it didn't seem necessary.
mikeames
Senior Member
- Location
- Gaithersburg MD
- Occupation
- Teacher - Master Electrician - 2017 NEC
I was just picking it apart as usual for fun.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
My thoughts. And I teach second year apprenticeship. Frankly I have not been the best teacher, because I have tried to hard to be accurate at ties. Most of these students will never care what the difference is between and autotransformer and an isolation transformer, or regretfully the nuance of electricity taking all paths with the path of least resistance, usually being so overwhelming that the current in other paths is negligible. I have been arriving at the conclusion that I push the basics, discuss the nuance and reinforce and test on the basics. I need to make the "good enough" to perform and survive. They need to teach themselves to be successful. My phone number is available to them basically until I am dead and gone.
Mike explained this best in his bonding and grounding seminar. Much of this stems back to the days of edison where the water lines were the path back to the transformer on city connected systems. Since they were in the ground it became the effective fault path albeit a terrible one. However, the point at the time was valid the electrons would try to go to the earth as that's where their ungrounded conductor was connected.
Unfortunately it stuck and today we think of the ground as the effective arc fault current path. Also it wouldn't hurt for engineering profs to spend a day in mike's seminar's now and again, but overall the bigger problem is much like making changes in the code. The engineering curriculum is governed by the ABET accreditation body, you'll need to get profs who are willing to fight this fight to change it. And bear in mind as a prof I get negative credit for doing such things. I'm not there to teach, I'm there to bring in grants and publish. I'd be free to add it to my own classes but the deck is stacked against changing it writ large.
Unfortunately it stuck and today we think of the ground as the effective arc fault current path. Also it wouldn't hurt for engineering profs to spend a day in mike's seminar's now and again, but overall the bigger problem is much like making changes in the code. The engineering curriculum is governed by the ABET accreditation body, you'll need to get profs who are willing to fight this fight to change it. And bear in mind as a prof I get negative credit for doing such things. I'm not there to teach, I'm there to bring in grants and publish. I'd be free to add it to my own classes but the deck is stacked against changing it writ large.
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
And thats what I like about you. You are willing to sacrifice your own time to explain it to those who know less. That is the only way to keep humanity going. I can't stand people who are like "figure it out yourself" "its not part of your job, so why do you care" I think that attitude is in part why the lights can not stay on in Texas and elsewhere. You have to teach those who want to know, even if they don't "get it" the fist dozen times around. I've had to ask a hundred times how lightning works until it clicked for me that there is actually a difference in potential between the cloud and strike point.
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
Everyone and anyone capable of bringing mercy to humanity gets negative credit. Society as it stands actually helps the followers reach success, but fails the most brilliant leaders. The most painful aspect is the level of hostility one encounters when challenges the status quo.
My point is I get you, and you are a hero in admitting the obvious that most others deny.
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
hats off to the teachers who understand the concern here ...... ~RJ~
~RJ~- Status