30-Amp Power Mystery

[oldjohnt]

 

 

24 minutes ago, Wrknrvr said:

 I was thinking if you disconnect your inverter power from where it is attached now. Take a appropriate short adapter that you could plug your shore power cord into. And cut that short plug adapter in the middle, attach it to your inverter.        Now you have a known power source that you can plug into.   

  Now you can eliminate the shore power pedestal question.

 

    I did mobile rv repair for 12 plus years. Early on I realized I needed a way to test power from pedestals or other such places. So I bought short adapters, 30 & 50 amps, cut them in half, and now I could test power much easier. Just be careful when doing such testing. 

Vern, good tips in your most recent post above HE NEEDS AN EASY WAY TO SEE IF THE PROBLEM IS AT/IN THE PEDESTAL   OR   IN HIS RV ELECTRICALS including its cords, connections, switches, plugs, etc. etc.  Of course, plugging into another pedestal is one way or else measure volage UNDER LOAD at the pedestal and then at the input of his AC Power distribution panel. WHERE IS THE BAD CONNECTION OR CORD OR OTHER PROBLEM CAUSING THE VOLTAGE DROP ???

 I dont know for sure just how or where he is swapping, substituting or temporarily hardwiring his Inverter output (or any pass through) and the shore power so the feed gets to his AC Distribution Panel and how or where he is by passing (or eliminated) any Transfer Switch Functions so we have accurate Shore versus Inverter voltage readings.  

Oh if we were there armed with your splitter and our meters this would be easier lol

Thanks for your wisdom and experience, I appreciate it

John T 

[Kirk W]

15 hours ago, jesfl45 said:

my focus for that remains the (very old) 50 amp power pedestal to which I have been connected.

Another hint that might be an indication of the problem that you have would be to examine the blades of the plug that you have been using to mate to the RV park outlet. If they show signs of arcing or having been very hot, that would be further reason to suspect that outlet is bad. Old, weathered outlets often get weak in the spring action that clamps to the blades of the plug and as they do so they will introduce resistance which means heat if under load or they may even have momentary or partial gaps that cause arcing. 

[Wrknrvr]

   Some times I have twisted the blades on the male end. Just a tad biitttt. And made things work.

  Vern

[oldjohnt]

1 hour ago, Wrknrvr said:

Some times I have twisted the blades on the male end. Just a tad biitttt. And made things work

Vern, I always clean up shine n polish the plug blades to get any carbon and oxidation removed and/or even spring or bend them just a tad. We still don't know if his problem is in the pedestal (hope he tries a different one) but if its old n worn out it wouldn't surprise me one bit, in 50 years of RVing I've seen a ton of them worn out or ones that have overheated and are all loose and resistive with bad burned internal wiring connections. If he checks the voltage at the Pedestal and then at his main AC Panel input as I advised under load we will know more. When things overheated its no tellin where the problem is now regardless if in the Pedestal or some of his electricals. Even a badly burned or faulty pedestal or receptacle can show 120 VAC to a volt meter, but try to pull current out of it and things go south  QUICK

 Take care now

John T

    

[Wrknrvr]

  In situations like this it would nice to have a video conference with the person having trouble. Like reaching out of there computer and point to a certain location to test or what to do next.

 

    Vern

  

[Kirk W]

2 hours ago, Wrknrvr said:

Like reaching out of there computer and point to a certain location to test or what to do next.

And then looking out of the computer to get a close look at things! 

[oldjohnt]

3 hours ago, Wrknrvr said:

In situations like this it would nice to have a video conference with the person having trouble. Like reaching out of there computer and point to a certain location to test or what to do next.

The technology certainly exists with each side using their smart phone, my wife and kids n grandkids do it all the time but it's not been my thing lol..........Even easier if we were there armed with our own meters it would be a matter of minutes wayyyyyyyyyyyy less then we have spent trying to help the OP on this forum. Wonder what the voltage reads at the pedestal and at his panel as loads are applied hmmmmmmmmmmm ............... 

HOWEVER as an Attorney Engineer all sorts of red flags start flapping imagining electrical dudes trying to instruct some novice to check lethal voltages here n there YIKES lol

John T   

Edited February 16, 2022 by oldjohnt

[jesfl45]

 

Good morning every one of you wonderful forum participants here . . . 

. . . again, I must say how grateful I am!

I was unavailable yesterday because of a family matter, and that again will be the case until later today or tomorrow (Thursday) morning. I cannot get back to the details of all your recent forum comments until later.

However, quickly, I do want to provide some additional information.

Importantly (I believe), I have tested and tested and tested, ad infinitum. I have photos and reading for every voltage and continuity test I have completed. I CAN compile those 20+ photos and digital multimeter readings shown in the photos. But, honestly, at this moment, that seems like a waste of my time.

In summary:

(1) I have tested voltage at every single connection from the power pedestal to the breaker connection in my RV's WFCO power panel. Every single wire and or receptacle a steady 122v to 123v. I know the main 30 amp breaker is working properly, because it is on at this moment as I use my solar inverter power (through the power panel). I read 123.7 volts at the power panel and 124 volts (no decimals available) on my little plug-into-an-outlet voltage meter. All is well on voltage from  my solar inverter.

Similarly, in my voltage tests of the 120 volt power (not connected at all with my solar inverter power system), I read 122.? to 123.? volts. with minior deviations.

(2) I also ran continuity checks end-to-end on every cable and wire from the RV park power pedestal to my interior WFCO power distribution panel.  (And, a few other non-120v wires, too, while I was thinking about it.) every single cable/wire tested 0.00 (+/- 0.01-0.02). 

As an afterthought, however, I awakened in the middle of the night last night wondering whether or not I should have tested continuity from the 50A-30A dogbone through the end of the temporary cable I am using that is directly connected to the power distribution panel. (I can drag the pedestal plug end inside the RV to the power panel.) That test result would be through all connections. Theoretically, I assume that continuity reading will also be the 0.00 (+/-) as with the cables, but . . . ?  (I have tested voltage on that part of my connection, and it is 122-123 volts.) If a continuity test of the entire connection length tests bad, that COULD (?) be the problem? My guess, however, is that continuity will be perfect with that reading, too.

Now a quick question.

I subscribe to diagnosis that "the load is the problem" at this moment. As suggested in comments, I want to test the power pedestal WITH A LOAD. However, at my level of knowledge, I don't know how to do that test?

Someone may already have answered my "load" question. If so, I missed it in my quick skim a short while ago.

Shore power will not come on inside the RV when I turn on the main 30 amp breaker in my power distribution panel. Ergo, I can't turn on or plug anything to "load" the power supply and run that test? I would have to directly connect something to load the power pedestal voltage as the test. So: (a) I don't really know how to do that, and/or, (b) my cautionary instinct screams "stop, that may be dangerous!" 

My only novice idea is to use the 50-amp to 30 amp dogbone; then plug that into a 30 amp to 15amp dogbone or adapter; and then plug something like my (inexpensive, easy to replace) heat gun into the 15 amp AC plug?  I am assuming my (new) clamp-type multimeter will/should be able to measure the flow through both the 50a-30a and 30a-15a dogbones? It's the only way I can figure how to "load" the power with a plug in the single 50 amp power pedestal connection. Am I correct?

Will that work? Will it reveal whether the power pedestal wiring just can't/won't take a load? 

If yes, I will do that as soon as I return when daylight work time is available.

I must now leave for the morning. I'll hope to get back to my power mystery tomorrow morning.

Again, thank you to everyone for all of your helpful thoughts.

Jim (jesfl45)

 

[Darryl&Rita]

13 hours ago, oldjohnt said:

all sorts of red flags start flapping imagining electrical dudes trying to instruct some novice to check lethal voltages here n there YIKES

That's why I've been quieter during electrical trouble posts, the last few years. Nothing personal to OP.

[Kirk W]

2 hours ago, jesfl45 said:

My only novice idea is to use the 50-amp to 30 amp dogbone; then plug that into a 30 amp to 15amp dogbone or adapter; and then plug something like my (inexpensive, easy to replace) heat gun into the 15 amp AC plug? 

That would check it out or if you have a portable heater with high & low settings you you could test at 2 different levels. 

2 hours ago, jesfl45 said:

  I am assuming my (new) clamp-type multimeter will/should be able to measure the flow through both the 50a-30a and 30a-15a dogbones?

How-To use a clamp-on ammeter

[Danfreda1]

Unless I missed it I didn’t see anything about a power management system/ surge protector. Maybe it is seeing something and not let it pass through? High low voltage? Have had that happen to us a couple months ago. Just a thought 

[oldjohnt]

On 2/16/2022 at 9:48 AM, jesfl45 said:

My only novice idea is to use the 50-amp to 30 amp dogbone; then plug that into a 30 amp to 15amp dogbone or adapter; and then plug something like my (inexpensive, easy to replace) heat gun into the 15 amp AC plug?  I am assuming my (new) clamp-type multimeter will/should be able to measure the flow through both the 50a-30a and 30a-15a dogbones? It's the only way I can figure how to "load" the power with a plug in the single 50 amp power pedestal connection. Am I correct?

Will that work? Will it reveal whether the power pedestal wiring just can't/won't take a load? 

YES thats "one way" to draw load current (PROVIDED you have correct and adequate adapters) and measure the voltage so you can see what happens when a load is applied. AGAIN if there's 120 VAC at the pedestal WITH NO LOAD NO CURRENT DRAW but it drops (drastic if bad enough pedestal) when you draw current THAT MEANS THERES SOME SORT OF A FAULTY RESISTIVE VOLTAGE DROPPING CONNECTION OR WIRE OR TERMINAL OR RECEPTACLE OR BURNED CONNECTION ETC........IE A POWER PEDESTAL PROBLEM INDEED .......It could be alllllll thats needed inside the pedestal is a new receptacle and/or repair and replace any burned or loose or resistive wiring connections which the park owners need to do !!!!!!!!!!!!!! Hope the problem is NOT in your RV wiring *&^%^%$ Of course, the problem may be upstream of the Pedestal where its feeder wires splice in BUT NO MATTER ITS STILL THE PARKS PROBLEM AND THAT PEDESTALS POWER IS BAD. 

NOTE A Volt Meter (uses two leads) will read the Line (Red or Black) to Neutral (White) voltage (set on appropriate AC Voltage scale) to see if it drops when a load is applied...  

NOTE A clamp on AMMETER measures current flow through A SINGLE CONDUCTOR (such as Line or Neutral) which passes through its closed open and clamp over loop. You would have to isolate and separate the Line and Neutral Conductors to measure their current. If you clamp over both the currents cancel and it will read zero

NOTE a non clamp on series ammeter can measure current flow in and out of it but I doubt your meter can handle high currents

If at the 15 Amp receptacle (where you plug your heat gun) you have a dual splitter or a 3 outlet cube adapter you can use the spare non used one to insert your two volt meter leads, Line and Neutral, to see what the voltage does when you turn on the heat gun plugged into one of the other receptacles

Actual current (you could easily compute as Power = V x A) so long as less then 15 amps, isn't as important to know AS WHAT THE VOLTAGE DOES so Id try a two lead AC volt meter (set on high enough voltage scale) plugged into a spare 15 amp cube or Y receptacle then turn on your heat gun and read voltage (if it will even work that is ???) low voltage may damage some tools or appliances so turn it off quickly if it fails or smokes and/or voltage drops drastically...If it doesn't work because the voltage drops drastically and the pedestal (or its upstream wiring) is bad NEITHER will big RV loads DUH 

NOTE there's a chance ONLY ONE of the two legs of the two in a 50 amp receptacle is bad and the dogbone only uses one of the two legs ??? Wonder if your 30 amp one leg RV is utilizing the bad leg ???  I guess so if nothing works when plugged to a pedestal using that "bad" leg ??  JUST SAYING

NOTE there a chance ONLY THE NEUTRAL in a 50 amp receptacle is bad, however if its bad neither leg will work

OR ELSE plug to a different pedestal is another test method

I expect and hope the pedestal is the problem NOT your RV but hey thats possible you know !!!!!!!

 Let me know what happens, use caution and be prepared for heat or smoking. If theres excess current flow a circuit breaker should trip but Im disappointed there's none in the Pedestal  ??????? Also another safety concern, such a breaker would be 50 amp rated and you're using 15 to 30 amp gauge wire !!!!!!!

USE CAUTION IF YOU DONT KNOW WHAT YOU'RE DOING HIRE A PROFESSIONAL

 John T there's more I can say but that's enough for now, I tried to ONLY ANSWER YOUR SPECIFC QUESTION       

Edited February 17, 2022 by oldjohnt

[jesfl45]

IT AIN'T THAT! (The pedestal loading issue.)

Pix below of a quick load test just after the surge protector. Load does nothing abnormal. I am deflated.

Family is in town, who I only get to see every two years. So, I'll be mostly unavailable until mid-week next.

Keep in mind that everything is completely disconnected when I test. I have been wiring the main power source wire directly to the WFCO main breaker connected wire-to-wire with heavy duty twist nuts. If AC is connected, solar inverter is completely disconnected, and vice versa. I'm having my Onan 3600 kw genset serviced next week and I will fire it up and test the genset power through the main breaker panel. Through all this, it has been completely disconnected . . .as is pedestal power right now as I use my solar inverter power.

As soon as I can, I'll make the list of all the voltage and continuity readings I've taken at every connection through the wiring. But, they were all perfect, so I don't get.

Thank you again for everyone's comments and suggestions. I need to stand back and enjoy some family time . . . and clear my (frustrated) mind from all of the mystery electrical power problems.

Jim (jesfl45)

P.S. Guess I can't send but one pix at a time in this limited system. I reduced the three to 17% of original size and saved at low resolution. No time to go back through that Photoshop process again. Sorry. FYI, normally the pedestal shows 122-123V when I check, but 87 degrees right now and many people in the RV park are running their AC. The no load reading was 118.9 volts.

 

[Jaydrvr]

For picture posting, start with this page.  

Once you've created a link there, strip (remove) the (IMG) front and rear, then use the Other Media link to insert the remaining link. Jay

Edited February 18, 2022 by Jaydrvr
Correction

[Darryl&Rita]

39 minutes ago, Jaydrvr said:

strip (remove) the (jpeg) front and rear,

Jay, the stripping needed is the IMG portion.

[oldjohnt]

2 hours ago, jesfl45 said:

 

 

Edited February 18, 2022 by oldjohnt

[oldjohnt]

On 2/17/2022 at 4:54 PM, jesfl45 said:

Pix below of a quick load test just after the surge protector. Load does nothing abnormal. I am deflated.

Sooooooooo if its NOT a Pedestal problem (IE the voltage stays up even under a heavy load) you're left with your shore power cord or a plug or receptacle (bad or not wired right) or a loose/burned/resistive connection or the Transfer Switch ifffffffffff its still in play ?? Hard to know sitting here with such little info to go on.

Still remember your RV uses ONLY ONE of the two legs of 120 VAC out of a 50 Amp pedestal and one may be good the other bad !!!!!!! You have only tested ONE leg !!!!!!!!! A 50 to 30 Dogbone Adapter only connects to one leg of the 50 Amp but if that's the same leg that feeds the RV ???? and it tested good, you're right back to the Pedestal being okay....

 If you turn OFF the Main and alllllllll branch breakers,,,,,, Get plugged to a GOOD Pedestal,,,,,,,,,,,,,,,Put a volt meter on the main panel AC Input,,,,,,,,Then turn on main and then branch breakers and turn on or plug in tools/appliances  ONE AT A TIME  that "should" place a load on the system to see if/when the voltage drops ?????? IF SO and the pedestal is good ?? the problem could be 1) Power Cord 2) Power cords plug (wired right?) or receptacle and plug on RV or is it hard wired there ?? where it connects to RV 3) Wiring and connections from RV input to transfer switch or main panel 4) TRANSFER SWITCH iffffffffff its still in play ??????   Problem could be in either the Line or Neutral   

NOTE If voltage is good at the pedestal as you indicate even under load ?? but drops at the main panel when you apply loads,,,,,,if you had a way to check voltage at various vantage points/junctions/connections/cords/plugs/receptacles BETWEEN Panel and where RV plugs to pedestal you can find the bad place where voltage is dropping........

NOTE the above paragraph assumes there's a connection from shore power cord plug into pedestal alllllllllllllll the way to the main panel, I don't know if that's true or not, I dont know for sure if/how the TS is by passed and out of play

 If the pedestal is good that's about all I can think of that may be the problem but not being there and knowing how all is wired I cant help you much more, but hey give me credit I sure tried lol.

 Best wishes and good luck

John T  

Edited February 19, 2022 by oldjohnt

[Wrknrvr]

   Just by chance, do you have one of these in your breaker box.

[jesfl45]

 

I have some time this morning before family obligations, for the day.

I thought I would post with the hope of another idea to solve my mystery problem.

Once again, up front, I want to say how much I truly appreciate everyone’s ideas and suggestions. They have been immensely helpful in narrowing the possibilities of my very frustrating electrical problem.

Also, I know I haven’t answered each individual query. That's discourteous. My apology. There’s just been toooooo much. Toward that end, I’m trying the summary below to catch up somewhat.  

(Note: I have, and would send, photos of everything mentioned herein and elsewhere if not for the unfortunate and discouraging-to-good-communication multi-stage photo-posting process required for this forum. John T., I appreciate your direction to the conversion link website. I tested. At my throttled 5mb/s cell internet speed, it takes 30-50 seconds for just one of my hi-res cell phone pix to load and convert. Overall, a minimum of 2 minutes each, often more, to complete a posting of each image. Sending all of the photo documentation I have of the points below = about 20 images to convert and post = 40 minutes to one hour of time. That’s just not happening. One or two critical images, maybe. Too many questions asked to provide photo “proof” for all answers.)

For anyone joining this post recently, the (still-a-mystery) problem is:

(a) Overheated twist-lock 30 amp power cord receptacle at rear of RV.

Note: Everything was working fine prior to overheating likely caused by my absent-mindedly leaving hot water heater on when air conditioning kicked on while also running TV, computer, lights, etc. How many amps is that? Oops.

(b) Replaced with high quality 30 amp SmartPlug.

(c) Power pedestal power would no longer work, even though voltage into main 30 amp breaker on WFCO power distribution panel was 122.5 volts. Tested many times hard-wired directly to power panel main breaker.

(d) However, solar system 3000 watt inverter power works perfectly when similarly hard-wired to main 30 amp breaker (after disconnecting pedestal power). Loaded by running 1500 watt microwave, no problem on solar system power.

Now, a few qualifying information bits as reminders:

-- The (once-discussed) transfer switch is physically in the trash out of the RV. It is not a factor in anything.

-- I am 100% confident all wiring connections are connect (and I have photos, except for the huge barrier noted above).

-- Absolutely nothing but one power source at a time is hard-wired to the power panel for my testing -- either the power pedestal power or my solar system inverter power.

-- the generator has been completely disconnected (awaiting service) since I removed the transfer switch. It is not a factor whatsoever.

-- I have tested every connection many times. Both voltage and continuity tests are perfect on every part of the power pedestal connections -- dog bone, power cord, 30 amp receptacle at RV rear, original in-floor wiring from power receptacle to power panel (plus a directly connected, temporary 10/3 “test cable” which is just easier to hard-wire on/off when I change power sources for testing.)

-- Progressive Industries portable surge protector after the pedestal works fine. Proper blue/green lights on. I have tested the pedestal power connection with and without it. No difference. Contacted the company last week. They assure me it is perfect.

But, one thing I HAVE NOT TESTED is each separate section of the power pedestal connection system WITH LOAD. Since I have tested voltage and continuity on each section (all perfect), I expect no issue. However, I have figured out how to do a section-by-section load test and I will do so when I am back at my RV. That will satisfy my curiosity and any other questions.

So, from the last of the posts on this forum backward:

-- No SquareD Surgebreaker in my power distribution panel. Never seen one before.

-- I cannot “get plugged into a good pedestal” easily, without a major move of the RV. Once, I was ready to do that. BUT, now, it makes no sense to me to go through the hassle of moving the RV for the same exact result . . . since the load test on the pedestal power showed no voltage drop?

If the power pedestal tests good under load, why would a different pedestal make any difference at all? To be clear, there is no good power pedestal reachable with my 50’ of 30 amp power cord extensions plus about 20’ remaining of my main power cord (after I cut off several feet at both ends of the main cord to assure sure there was no overheated wire remaining before installing new plug/ receptacle). That’s a total of about 70’ of power cord available. (Buying 3-4 more 25’ extensions to reach the closest “good” power pedestal is not in the cards.

 -- I do understand that because I am using a dog bone I am testing only one leg of the power pedestal under load. Previously, I multi-meter tested the 50 amp power pedestal receptacle and it tested perfectly on both left/right legs and the main leg.

But, why does it matter, since whichever single 30 amp leg works perfectly with no voltage loss when loaded with a direct 1500 watt load through the 50/30 dog bone? Trying to learn something new here.

-- I do not believe the voltage drops at the main distribution panel under load. BUT, I realize it is not tested. Upon considering that, I suppose it is possible? SO, I have figured a way to test with a 1500 watt load immediately BEFORE the hard-wired connection to the main breaker. I will do so.

However, I do not know how to test with a load AFTER the main 30 amp breaker when hard-wired because there is no power when any of the secondary circuit breakers are turned on? Suggestions?

REMINDER (Re: WFCO Power Distribution Panel)

(1) Secondary breakers do not receive power from power pedestal source when main 30 amp breaker is on, even though 123-123 volts is shown on line going into the 30 amp main breaker at the hard-wired connection in back of the breaker and at the connection terminals on the front of the power panel at the breaker directly.

(2) BUT, all secondary breakers and circuits work perfectly when hard-wired to my solar system inverter, always showing 123-124 volts on my wall outlet voltage meter. High-load microwave (1500w) microwave works fine.

If the main 30 amp power distribution panel breaker was bad, why would it work fine with the solar system inverter power?

Ergo, these questions seem relevant:

-- Is there somehow a strange difference in the power from the (very old) power pedestal vs. the (clean?) power from my solar system inverter that causes inverter power to work and pedestal power to fail?

-- Can a breaker switch somehow be nearing failure so it would allow one power source (solar inverter) to work perfectly while another source (pedestal) would not?

-- Is there some other connection in the WFCO panel that could be causing this problem? If so, how do I check?

-- Is there any other rare electrical anomaly that could cause this works-one-way-but-not-the-other problem?

Later this week, when I’m back at the RV full time, I’ll replace the 50/30 dog bone and all the power cords from the pedestal to the power distribution panel. Although, I believe that will prove to be a complete waste of my time and money.

OK, I’ve run out of steam and time for this morning. I must continue my work further backward on questions and comments at another time.

Again, thank you to all.

I am still hopeful someone will think of or know some odd or tricky little thing that is the cause of my no pedestal power mystery?

 Jim (jesfl45)

[Kirk W]

I continue to wish that there was some way that I could come to the RV with my meter and trace out exactly what you have and take my own readings, and observe yours. I have doubts that we really understand how you have your RV wired. Have you drawn a schematic of it by any chance? If so could you scan it and send it as a .pdf file via email? That same thing goes for your pictures. I don't remember if you have said where you are, but unless nearby I doubt that any of us can come to your location. I share your frustration as I still believe that if I were physically on site I would be able to determine where the problem is. 

[Randyretired]

I hate to get involved as you don't need a bunch of people all giving advice.  However, one way to determine if it is a problem under load is to turn off all the breakers in the RV.  Measure the voltage at the RV breaker panel.  If it is good then drops when the breakers are turned on it is a load problem.  If the power isn't there then somehow it isn't connected to the source.  

Edited February 20, 2022 by Randyretired
Add RV breaker panel.

[oldjohnt]

Hello once more Jes, THANKS FOR THE UPDATES the more you help us the more we can help you

RANDY please help and please get involved, I've tried about all I can think of above lol any other ideas ???

 Jes, I have an answer to that, it's basically the same as what I already spoke of above, but I will go over it again once more in detail.

1) Once you are hard wired to the AC power distribution panels INPUT (ahead of and before the 30 Amp MAIN breaker) input via your shore power cord and any of its in series plugs receptacles and splices/junctions and it plugged to the pedestal via the dogbone WITH MAIN AND ALL BRANCH CIRCUIT BREAKERS OFF,  I take it your read a good 110 to 120 or so volts right ??????

2) So how to apply a load you ask ?? As you turn on BRANCH breakers (typically 15 or 20 amp) one at a time you should SUBJECT TO what tools/appliances/chargers/fridge/elec water heater etc. are served by those individual BRANCH breakers, draw load current. Devices such as a Converter/Charger or a fridge or elec water heater set to operate on AC might be energized and draw current, but if none do, plug a high current device like a hair dryer or microwave or elec space heater or a heat gun into one of the branch circuit receptacles AND WHEN YOU FLIP THAT BRANCH BREAKER ON THAT SHOULD DRAW LOAD CURRENT.

3) Sooooooo does the voltage before and ahead of the MAIN 30 Amp Breaker (thats fed via your power cord and its plugs and receptacles and plugged to the pedestal) drop drastically when loads are applied or not ????????????????

IF SO BUT NOTTTTTTTTTTTT if your Inverter feeds the very same dist panel ahead of and before the main breaker in the same exact location, my best guesses as to the cause not being there are as follows

 a) Your power cord has a bad internal conductor or other fault or short or open, maybe caused when things overheated

 b) One of the Plugs or Receptacles is miswired or bad (At cords end that plugs to pedestal, where cords other end plugs into RV, the receptacle in the RV,,,,,,,,,,,Any splices or junctions or terminals or wiring blocks or busses located ANYWHERE between pedestal and the input to the dist panel.

 c) A faulty or miswired or burned or loose or corroded splice or junction or wiring connection anywhere between power cord plug and the main panel

QUESTION AND NOTE This assumes your Inverter and the shore power cord (including plugs and receptacles) are connected at the SAME PLACE and the Inverter works but NOT shore power is that correct ???????????????????

NOTE 1 while you DID NOT test BOTH legs at the pedestal, if you're using the same 50 to 30 dogbone adapter by which the pedestal load tested okay with a heat gun ??? (if thats true I wasnt there??) that should be the same leg youre plugging your shore power cord into    BUT I CANT GUARANTEE THAT ONLY SAYING.. If one leg of the pedestal is bad and that's the leg you're plugged to then the RV wouldn't work properly, and it may be fine but the pedestal is bad. Again not being there I can't guarantee the pedestal is good but have proceeded herein like it is, however, it could still have a problem !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!    

If you rigged a known good substitute 30 amp cord with a NEMA TT 30 plug into the pedestal/dogbone (TO A GOOD TESTED LEG) and the other end hard wired to the main panel at same place the inverter allows all to work fine THAT WOULD TELL YOU THE PROBLEM IS IN YOUR CORD OR A BAD OR MISWIRED PLUG OR RECEPTACLE OR SOME OTHER SPLICE OR JUNCTION    

DISCLAIMER If I (50 year RV owner, past dealer, and electrical engineer) were there I may be able to locate the problem in a short time however over the net its difficult. Myself and others have spent a great amount of time trying our best to help and glad to do so but with your limited electrical experience and doing this over the net its tough lol

Iffffffffffff Inverter works yet the shore power does not when hard wired to the exact same location, problem about has to be Pedestal,,,,,,,Shore power Cord,,,,,,Plugs or receptacles (bad or miswired), Junctions or splices and overheating may well have been the cause. A loose/burned/resistive/open Neutral can cause all sorts of problems and its a conductor just like the Line conductor is and EITHER can be bad. I might envision problems if the Neutral and Equipment GroundING Conductor were mis matched or substituted or had opens or shorts  BUT IM  NOTTTTTTTTT OPENING THAT CAN OF WORMS NOW LOL

ENGINEERING THEORY even with a very bad very resistive conductor or connection or cord or plug or receptacle you can still read 120 volts with a meter HOWEVER once you draw current so long as it does NOT burn the conductor open there will be a V = I x R Voltage Drop across the bad connection so there's not enough voltage left to power RV devices 

Thats is and all I can do for you now LET ME KNOW what you find and I will keep trying my best to help. If any of the other very fine electrical minded gents have more ideas as to what the problem is let us all knowwwwwwww..  Watch it be something sooooooooooo simple we all missed it lol

Best wishes to all here

John T

Edited February 20, 2022 by oldjohnt

[Randyretired]

John, I am late to the party but there seems to be a concern that this may be a problem when under load or just not connected.  That is what I am trying to address in my post.  If the RV is plugged into the pedestal and all of the breakers are off in the RV there should be voltage at the RV panel.  If the voltage isn't present then there  isn't a connection to the source (wiring for instance).  If there is power but it diminishes or goes away when the breakers are turned on it is a load problem.  From that we can try to trace the problem.  Has this already been done and do we have an answer to that?

[oldjohnt]

18 minutes ago, Randyretired said:

John, I am late to the party but there seems to be a concern that this may be a problem when under load or just not connected

Thanks Randy, somewhere wayyyyyyy up above based on his postings I got the impression THERE IS A CONNECTION (albeit perhaps bad) AND VOLTAGE IS PRESENT but nothing is working (Load problem) but there's been soooooooo much and he's not electrical minded, so I wouldn't bet a lot on that lol 

 If there is NO voltage whatsoever, it's an OPEN connection, but still I see it in the Cord or Plug or Receptacle or junction or splice especially if it happened only AFTER the overheating.     

 In my post and questions for him above you can see I asked him IF VOLTAGE WAS PRESENT with all turned off so once he responds this can be answered. Regardless he has to locate the bad or miswired cord or plug or receptacle or splice or junction or where the connection is lost/open.......... 

THANKS for your help, oh if we were there only a few minutes lol

John T

Edited February 20, 2022 by oldjohnt

[Randyretired]

5 minutes ago, oldjohnt said:

Thanks Randy, somewhere wayyyyyyy up above based on his postings I got the impression THERE IS A CONNECTION (albeit perhaps bad) AND VOLTAGE IS PRESENT but nothing is working (Load problem) but there's been soooooooo much and he's not electrical minded, so I wouldn't bet a lot on that lol 

 If there is NO voltage whatsoever, it's an OPEN connection, but still I see it in the Cord or Plug or Receptacle or junction or splice especially if it happened only AFTER the overheating.     

 In my post and questions for him above you can see I asked him IF VOLTAGE WAS PRESENT with all turned off so once he responds this can be answered. Regardless he has to locate the bad cord or plug or receptacle or splice or junction or where the connection is lost/open.......... 

THANKS for your help, oh if we were there only a few minutes lol

John T

Yea John if we were there it would be easier.  If you and Kirk haven't found though it probably  won't be easy.  I will try to work with you to bring another set of eyes.