Completely agree. Wire nuts were never intended for use in anything that moves. Not even allowed by ABYC for marine applications.

Rob

Subscribed to this series of posts - stumbled across them and am enjoying the notes on things to think about.

The number of things I don't know about RV's far exceeds what I do know so even just knowing to ask questions about something is helpful. Have had such a miserable experience with the local Grand Design dealer I'm actually taking my RV in to an independent dealer this next weekend and paying one of their techs to walk me through the different systems again to refresh myself and also get some pointers on inspecting the different sealants around the unit, things to look for while washing it, and maintenance of things I may be overlooking. (tried repeatedly to do this with the local Grand Design dealer with zero luck)
With regards to wheel bearings & brakes and the insurance issue - it's gotten so the only people who can afford those types of things are the shops that do them on a daily basis. For someone who's doing repairs as a retirement gig to keep themselves occupied while supplementing their income, probably better to stick with the misc. maintenance & repairs. (which is a shame as there are some very talented people with a lot to offer to an industry in dire need of skilled/talented people!!!)
Remember the counterfit bolts/nuts issue a few years back - got where if it's something I need to count on/trust I only purchase from a few select sources.

Thank you for taking the time to share what you're learning Howard!
Chris

howson Howard, I picked up one of these https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1 to assist in not having to stab the probes into a socket to test it. Also allows one to to amp draw testing without need to make a "special" chord with single runs of stranded wire (or stripping out an electrical cord).

I had done some work on other GDRV owners rigs and Jerry heard about it. He told me that I was welcome to do warranty work for them, but to send them an invoice for my labor. But there was a caveat. he told me that I'd need to get liability insurance too. I passed. Now, I let the owners do their own work and I just coach them while holding a cold beer in my hand.

Jim

21 Sep (Day 7)
Today was more about electricity, specifically 120vAC. Step up and step down transformers, the critical requirement that the neutral and ground are NOT bonded anywhere inside the RV (didn't cover the "why" this is so important, just that it is).

We then went into wiring, the different gauge wiring, and the different requirements for AC and DC. (DC requires stranded.) The topics of insulators and conductors was further explored with examples of the types of each kind.

Umbilical cords were covered in-depth, along with the proper way to check a pedestal and what to look for when inspecting a cord. They are essentially just large extension cords, so "common sense" covers most of what you'd look for in the larger cords. The instructor recommended DeoxIt to keep the contacts clean on both ends of the cord. I think Gene ( gbkims ) was the first to recommend this cleaner on this forum. (If not--sorry for my faulty memory.)

It's also good for the contacts on the 7-pin connector (both on the truck and the trailer.) https://www.amazon.com/CAIG-DeOxit-C.../dp/B07YZPB8RV



The instructor (it's "Bob", not "Rob" as erroneously reported earlier) brought out a few Power Distribution Centers and showed the different configurations of circuit breaker orientation, as well as the identification of the neutral vs ground bars. (Easy to identify the neutral bar since it is always insulated from the case.)

We then covered Automatic Transfer Switches, EMS' (he had a Surge Guard we could inspect), and the Hughes Autotransformer. The latter created a bit of a discussion but we didn't go too in-depth. Bottom line: instructor was quite adamant that an EMS was (I may be putting words in his mouth) "mandatory". Of course I agree--cheap insurance against preventable damage via an errant power pedestal, or low/high voltage.

The end of the day was a surprise--we took a test on Basic Electricity. (I passed.) For the sake of test integrity I won't address the one area where I almost got two questions wrong. It was a case of "Who's On First" (terminology). I put aside what I thought I knew and chose the answer that best reflected what the instructor stressed...and got them both right. Now I'll go back to using the terminology as I've always known it--regardless if Abbott can figure it out or not. ("Abbott", of course, being a reference to the comedian from Abbott and Costello and their "Who's On First" routine. See the video in post 1 if you have no idea what I'm referencing!)

Howard

Most important question - did they get the AC fixed? Glad you passed the test (no doubt you would). Carry on professor
Keith

LOL...yes...the AC was fixed over the weekend. So cold in the room some of my classmates are bringing in coats!

Follow-up to the ground and neutral bonding reference in post 35. Benjamin Sahlstrom has a terrific explanation in his video.

In one sentence: current should not flow on the ground wire back to the source unless there's a fault. If the ground and neutral are bonded in the RV panel, normal electrical loads will use the ground wire to return to it's source through the camper's wiring. This is not good. Neutrals and grounds are only bonded at the "first disconnect source". For an RV, that's the pedestal. ( Or in the case of a generator--the generator! See the video on the topic of "first disconnect source" that was posted in TucsonJim 's Does Your EMS Shut Down When Running on a Generator? thread.)

Here's Benjamin's video on why neutrals and grounds are not bonded in sub-panels:

Wed, 22 Sep (Day 8)

Batteries! All about batteries. I now understand how a hydrometer works, why a battery fails when the water level is not maintained, and why a battery at less than 100% SOC will freeze at a higher temperature.

All the information on the hydrometer and specific gravity was interesting, but in actual practice (if I was testing a battery) I'll check the battery by doing a load test after getting the manufacturer's specifications for the battery being tested. The exception is I'll pop off the vent caps on serviceable lead-acid batteries--if there's no water in a cell or multiple cells it's pointless to do a load test. The battery (if found with no water) will need to be replaced.

After the mind-bending morning session about batteries the topic shifted to converters. I had no idea there were different types. I doubt Grand Design trailers were built with Linear or Ferroresonant-style converters. Tomorrow we'll cover Electronic / Switch Mode Converters. I suspect that is the style of the WFCO typically used in our trailers.

[QUOTE=howson;n66446
The end of the day was a surprise--we took a test on Basic Electricity. (I passed.) For the sake of test integrity I won't address the one area where I almost got two questions wrong. It was a case of "Who's On First" (terminology). I put aside what I thought I knew and chose the answer that best reflected what the instructor stressed...and got them both right. Now I'll go back to using the terminology as I've always known it--regardless if Abbott can figure it out or not. ("Abbott", of course, being a reference to the comedian from Abbott and Costello and their "Who's On First" routine. See the video in post 1 if you have no idea what I'm referencing!)

Howard[/QUOTE]

Howard, I did get caught in the terminology of "Who's On First" on one of the electricity test.

Howard - While at the Quartzsite rally a couple of years ago, my truck wouldn't start. I had a hydrometer and was able to isolate a bad cell in one of the two batteries. It was a quick and easy test out in the desert where I didn't have a load tester.

Jim

Thurs, 23 Sep (Day 9)

More "Advanced" electrical theory and some hands-on with a battery and a linear converter.

The morning theory lecture covered the Electronic / Switch Mode Converter. This is the type of converter I think all GD trailers utilize. Certainly those of us that have the stand-alone WFCO converter have this type of converter. The advantages are quite significant over the earlier generation converters, including smoother voltage output and the three-stage charging capability.

Kind of useless trivia, but the Electronic / Switch Mode Converter down-converts 120vAC (60hz) to ~12vAC (35,000 hz)! It does this as part of the process to filter out the ripples (AC oscillations) in the output. The insanely fast oscillations are then removed through a bridge rectifier and voltage regulator circuit to provide a steady 13.6vDC (Bulk).

Thankfully the instructor just briefly discussed Silicon Controlled Rectifiers without getting into the weeds. If he'd gone into how PNP (or NPN) components work and are controlled by gate voltage I think half the class would have folded up their tents and gone home.

One component we did spend time on is the capacitor. This is logical since we'll be checking them in the air conditioners in a later block. More trivia (related to capacitors)--did you know a coulomb is 6.25e18 (6.25 * 10^18, or 6.25 billion billion) electrons? (I think Yoda 's head just exploded.)

From capacitors we transitioned to rectifier circuits. I was familiar with bridge rectifiers, but the fact you can rectify AC to DC with only two diodes and a center-tapped transformer (on the secondary windings) was new. Not hard to understand, just new (to me).

The last theory of the day was automatic transfer switches. These were relatively easy to understand after all the rest of the theory--really!

The end of the day was hands-on with a lead-acid battery and a linear converter.

There are several people here on this forum that, when they post something, I have learned to pay attention to their counsel. So since TucsonJim took the time to comment about hydrometer usage (and I was unfamiliar with them) I spent the time to get familiar with them. We did find two specific cells in one battery bad using the device. I found the device on the right in the picture below very easy to use. It automatically temperature-compensates and is so easy to read almost anyone could identify if the cell was good or bad. The device on the left had super-small lettering and was a little befuddling to read. (At least for a bunch of old guys trying to read the tiny writing.)



As I've already mentioned, we got to put our hands on a powered Linear converter, too. It was fun trying to figure it out without a schematic. I "got" most of it but Bob had to fill in a few gaps on some components that had me puzzled. Two distinct surprises: the huge "heat sink" (just a piece of aluminum bent into a U) that looked like the rear of the case was "live" with the 12v output of the rectifying diodes. I was very surprised such a large surface was "live". The other surprise were how the fuses along the front of the unit were powered. Even though they were in a row, they didn't all get their power from the same output of the Linear converter! I only figured this out because I could read the AC voltage "ripple" on the fuses were different. I spent most of the time helping my classmates which is like helping here on this forum but in person, face-to-face. (I enjoy it!)

Hope this wasn't too long. Now to study for a potential test tomorrow...(sigh).

Howard

Sorry Howard howson my head exploded years ago Differential Equations and Thermodynamics - Then Carl Sagan said something about a billion to the 10th power stars out there.
Sounds like your having fun,

howson That hydrometer on the right is the one I keep in my tool kit. They are so easy to use on a flooded battery. Of course, now that I'm running LiFePO4 batteries in the RV, it's another world. But I still keep the hydrometer handy in case another RV owner is having an issue.

Jim

Friday, 24 Sep (Day 10)
Done with electricity. At least the formal lecture part. The subjects we covered in the morning were Inverters and Charging Systems. As we dove into both legacy and newer inverter models it was amazing to see how much they've advanced in just the short time since I installed my Multiplus. (Victron still has the coolest tech IMHO, but there are some really good inverters out there capable of handling both legs of a 50A setup.)

Even though we are "done" with the formal Electrical part undoubtedly the knowledge will be leveraged when learning how to troubleshoot appliances (refrigerators, a/c units, furnaces, ect) in the weeks ahead. Not fun to take a test after lunch on a Friday afternoon, but at least there's no need to study "Advanced Electricity" over the weekend. (Yea!)

I am looking forward to next's week topic: propane! I'll learn to use a manometer and how to do all the tests on a propane system.

Howard