howson Howard, I don't use a clamp meter enough to justify the Fluke (I do own an a Fluke DMM for other things). I also needed the DC measuring capability as I do automotive work (for myself only) and it's nice to be able to check amp draws and such. Since I could not justify the price of the fluke, I opted for a https://www.homedepot.com/p/Klein-To...L390/312649921 which also does non contact AC sensing.

I'm certain by the time the course is over you will have quite a collection of strange things you did not know existed or would ever need.

If he comes in and says you need something like this https://www.amazon.com/Reed-Tool-PPR...1768050&sr=8-1 I suggest you run as the future is full of rhymes with WRAP.

We each need a "DAYS WITHOUT HAVING TO FIX SOMETHING" counter under our avatar.

Sep 16 (Day 4)
Reviewed yesterday's materials and then, of course, another test (#3). I passed but it was an interesting review. I've taken endless tests and was on an Air Force promotion board that wrote an exam, so I know a little about writing (and taking) a test. I assumed there was no way to win a debate with the instructor in front of the class, so I tried to calmly make my point and then agreed to "let it go" as it makes not one iota of a difference what my test grade is as long as I pass the course.

I will pause here a moment and give Rob (the instructor) kudos as he did listen closely to both my input and several others who questioned the "right answer". Rob even conceded that there were several possible right answers on a couple of questions and agreed to review them after-the-fact. I was surprised by his willingness to do this--not many (if any) of my former technical instructors or college professors were willing to listen. Rob did (and does) listen to our input, so I found that quite refreshing.

After the test we started electrical basics. The school teaches conventional current flow (positive to negative) versus electron flow (negative to positive). The instructor tried valiantly to explain the difference to those who have no experience or knowledge of electricity. Personally, I'd have stuck with just electron flow but that's just an opinion. I don't think most have a clue what he's talking about anyway.

Another head-scratcher was a debate on whether you can "create electricity". To me "create" is synonymous with "generate". The school's stance is no, the electrons are already there and can't be created, so electricity can't be created by an alternator. I'm still having a hard time with that definition since I'd define electricity as the flow of electrons. The flow of electrons provides energy to accomplish work. After a bit it dawned on me what was going on. If anyone's taken any classes they "get a clue" when the instructor foot stomps a point or repeats it many times, so since Rob wouldn't budge off the point and emphasized it many times I realized it was time to accept the school's definition and be ready to regurgitate it on command. But I still think an alternator "creates" electricity (but not electrons).

I received the Fluke 325, UEI Gas Leak Detector and Klein GFCI Receptacle Tester via UPS. (Fast!) The Klein tool is cool--didn't know these little testers came with a GFCI tester built-in (I have the standard version already that doesn't have the GFCI checker). If anyone's interested in a digital copy of the UEI or Klein manual I scanned them and converted so they are text-searchable. Send me a PM or post here if interested and I'll put a copy in the Tools channel.

There was also a lot of interest in the solar, inverter, and the other electrical upgrades in my camper. Naturally I enjoyed playing "Victron FanBoy" and showing off the cool VictronConnect app--those who were interested found it amazing that I could monitor my camper from the classroom. The DC-DC Converter was also a specific item of interest to one of my classmates. I suspect he'll be "ghosting" here (he's not a GD owner) and reading the "Tapping 12v..." thread.

Howard

Watching this closely Howard, sounds like a great experience so far. I can tell you from the rally that there was a lot of interest in DC-DC converters. I even recommended to done I talked to that or might make sense to do that ahead of solar off their travel would include a lot of drive says. I steered a lot of people to the board for discussion on it.

howson Howard, I can argue with a fence post until it concedes. Alternators do not create electrons, all of them were created long before I was ever around. Alternators (AC flow creators) and Generators (DC Flow creators) provide the necessary force to make the electrons move inside the wiring.

I refer to those 'bolts' as shear pins....
Interesting reading Howard. Keep it up!

The Law of Conservation of Energy dictates that energy cannot be created or destroyed but only converted. So in the case of an alternator, mechanical energy is converted into electrical energy + heat.

Howard, have your instructor to watch this video.

https://www.youtube.com/watch?v=jdSKlg80DjU

Jim

[QUOTE=howson;n66056I received the Fluke 325, UEI Gas Leak Detector and Klein GFCI Receptacle Tester via UPS. (Fast!) The Klein tool is cool--didn't know these little testers came with a GFCI tester built-in (I have the standard version already that doesn't have the GFCI checker).
Howard

[/QUOTE]

Howard,

Reading the Klein GFCI Receptacle Tester (RT250?) GFCI testing section "If the circuit remains energized, or if " > 5 sec" appears on the LCD" got me reading about UL943's trip time for Class A GFCIs.
Class A GFCI UL 943 inverse-time curve formula: T = (20/I)^1.43 where T is Seconds, I is current in milliamps

So (20/6)^1.43 = 5.59 seconds

I checked some of my older and newer GFCIs at home:
My SureTest applied 7.2mA to the GFCI outlets and trip time was in milliseconds.
3 different Leviton GFCIs from ~1990 tripped at 124 msec, 132 msec, 165 msec.
2 Hubbell Autoguard GFCIs from 2005 tripped at 29 msec, 30 msec.

Unless the DW is telling me one of her appliances isn't working, I just use the GFCI test button (when I remember to test).

I see a lot of the newer GFCIs being sold now mention trip times for 6mA of less than or equal to 25 msec.

gbkims (Gene),
I did find it odd that the instructions for the tester say to push the button and the GFCI should trip. Then repeat (after resetting the GFCI) but hold the test button for 7 seconds. Not sure what the tester is doing differently the second time (if anything).

Fantastic video, Jim--thanks for posting. I did not know how the electro-magnet regulated the output. I'll definitely suggest to my classmates and instructor.

Day 5 (17 Sep)
No test today (yea!). We continued on with basic electricity/electronics including a tsunami of glossary terms and schematic symbols. There are a lot of symbols that are new to me. The one that caught my attention is the difference between a chassis ground and an earth ground. The drawings I've made of my system use the earth symbol, so I'll need to update to show the proper chassis symbol.



The school teaches that there are three types of circuit representations we might see in the field. The one that surprised me was a schematic-like drawing called a ladder. This type shows the steps of a circuit as it functions, literally "stepping" up a level as the circuit engages different components. I've never used one (or seen one to my knowledge) including going way back to when I worked on copiers, and not in the USAF on aircraft. Maybe I've seen one and didn't realize what I was looking at?

A schematic, on the other hand, shows the entire circuit and is what I'm familiar with reading. The schematic printed inside the cover of the Dometic (Atwood) water heater is an example.

The final circuit representation is called a pictorial diagram. This is what I've drawn to show my modifications and installations since it uses actual representations of the devices and the connections.

The schematic is what uses all of the symbols I referenced earlier. There are over 50 symbols in the school's text that we're supposed to know. I feel sorry for my classmates that are completely new to all of this--they are definitely "drinking from the fire hose".

We then covered series, parallel, and series-parallel circuits. None of that is new to me. Finally, the day ended with an introduction to multimeters. Obviously that's not new material, either.

Next week will be more basic and then advanced electricity. I suspect the test will be on Friday.

Oh--and the AC company was installing the new compressor as we were leaving. I sure hope that thing works next week--sitting in a 90 degree (and hotter) classroom is no fun. But it's all good--one week down, nine to go.

Howard

Monday, Sep 20 (Start of Week 2 or Day 6)

Today was "Play With Your Multimeter" day. What it showed (to me, and it wasn't a surprise) is there's a canyon-sized difference between talking about something and doing something. The instructor spent a good amount of time explaining AC and DC as well as the various components, but I spent a lot of time assisting classmates since out of the 20 in the class only two of us knew anything about multimeters or how to measure the components. It was fun helping, though I was exhausted from all the talking (not something I do a lot). Some of the items the class measured include diodes, resistors, relays, bridge rectifiers, capacitors, and a wall socket (for 120vAC).

On one occasion the instructor asked me to check an amperage measurement with my multimeter to verify what other classmates were seeing on their clamp meters. I've actually never used the amperage reading side of my multimeter (though I know how) and didn't realize there was a DC and AC amperage mode. When I kept getting "0" (and was momentarily stumped) the instructor pointed out I had AC selected instead of DC. Doh! So much for being an "expert".

The afternoon was spent going over connectors and wiring. This is definitely an area I hope the class will actually get to practice, but I doubt it. I was happy the instructor stressed that "Scotch locs" aka "T-Taps" are not acceptable as a permanent repair. I piled on and said they weren't even good for temporary repairs. Too many other good options available for a quick repair without resorting to T-Taps.



A helpful tip I'd never heard (or considered) was when wrapping a wire nut with electrical tape is wrap the tape clockwise. The tension from the direction of the tape will help to hold tension on the wire nut. (I personally prefer heat shrink, but for those that use electrical tape...probably can't hurt to do it that way.)

Sounds like another good day. Brian and I can definitely commiserate with you on the talking from our experience at the rally. It is not a thing we normally do and I was shocked how exhausting it was.

howson
I can relate to your classroom experience. It is interesting to watch the class as they watch the instructor.

Several years ago, I wanted to take a Community College course on TIG welding (had to do with a stainless steel boat project). To get to the TIG course, I had to take their prerequisite courses in gas, stick and MIG. At one point the instructor (about my age) was describing that the welding should sound like “frying bacon”. I saw all the blank stares from the my 20-something classmates . . . and just had to ask . . . how many of you have ever fried bacon? I think three hands went up.

Rob

In my opinion, if you feel the need to tape a wire nut, you are using the wrong connector. Wire nuts should not be taped.