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Kirk, John. Electrical folks one and all. Please help.


Daveh

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SORRY, I HIT WRONG BUTTON BEFROE MY POST WAS COMPLETE LET ME TRY AGAIN

 

Good questions Dave, shows you're actually reading all this stuff LOL and it appears my discussion is sinking in yayyyyyyyyyyy. Let me try to explain a bit further and answer your new specific questions.

 1) You ask " but what happens ... like in a circuit coming off the panel in the RV"

 ANSWER if the Neutral comes off the individual branch circuit to say a light or toaster IT DOESNT WORK. It takes two wires Hot and Neutral having 120 volts across them to power a 120 volt appliance. Just a single wire, be it the Hot or the Neutral, doesn't suffice and I'm  sure you already understand that.

 Of course, if the Neutral comes off BEFORE it even gets to your panel:

 A) If its a 30 amp 120 volt RV   nothing works  WELL DUH

B) If its a 50 amp  120/240 volt RV absent a Neutral and loads are turned on fed from BOTH (L1 & L2) and they aren't the same resistance, one is gonna see high voltage the other one low voltage and things get FRIED !!!!!!!!!

 2) You ask  " would that impact the whole coach and give me weird readings at the panel"

  ANSWER

  A) If a Neutral to only a single branch circuit came off to your lights or toaster NO that doesn't impact the whole coach.

   B) If a Neutral came off BEFORE the panel YES that impacts the entire coach, see the above, 30 amp and 50 amp RV would be different.

 

Some of the terminology above is a bit fast n loose and inconsistent regarding the terms GROUND   NEUTRAL   LOOSE  FLOATING  so let me try to explain it using state of the art and NEC terminology used by electricians and electrical engineers.

1) Ground is NOTTTTTTTTTTTTTTTTT the same as Neutral and Earth Grounding the Neutral is NOTTTTTTTTTTT the same as Neutral Ground BONDING.   

2) Some Generators utilize a FLOATING  Neutral while others use a BONDED Neutral, although the utility electrical service like where your RV is plugged  uses a BONDED Neutral and the Neutral is also EARTH GROUNDED for surge and lightning protection and to keep the grid at one common low voltage reference IE Mother Earth.

3) Wayyyyyyyyy back when I practiced and attended NEC Seminars here's the terminology used............

  a) If the Neutral becomes totally disconnected THATS AN OPEN NEUTRAL

  b) If the Neutral comes loose yet still conductive via high resistance carbon THATS A LOOSE OR RESISTIVE NEUTRAL

   c) As the Utility DOES NOT utilize a FLOATING NEUTRAL (Its Bonded to the Ground Buss and earth grounded remember) the Neutral UNLIKE a floating Neutral Genset, is Bonded yet can still become loose/resistive or totally open. 

 Floating Neutral means its NOT Bonded, while it can be bonded yet loose and resistive in which case THE VOLTAGE is what's gonna "float" subject to current flow and the amount of resistance in the loose connection.........   

 

As well posted above it would be very possible to make this far more complicated, but it need not be if you just remember the basics of 120/240 volt Single Phase Three Wire Service.

The LV Secondary transformer is 240 volts line to line HOWEVER if you tap it in the dead center (Neutral) its ONLY 120 Volts from either end to the middle. A 120/240 volt panel has TWO hot legs L1 and L2 each fed off opposite ends of the 240 volt transformer THEREFORE L1 and/or L2 in that panel would measure 120 Line to Neutral PROVIDED NEUTRAL IS GOOD AND IN PLACE. If not in a 120 volt 30 amp RV nothing works and If in a 50 amp 120/240 RV  things may fry as the Voltage may be "floating" above or below 120 depending on the loads and current...........

 

ITS THAT SIMPLE you don't have to make it more complicated for purposes of this discussion yayyyyyyyyyyyyyy lol  

 

DISCLAIMER its IMPOSSIBLE TO EXPLAIN IN A PARAGRAPH what fills entire libraries and involves a lifetime of practice BUT HEY I SURE TRY MY BEST LOL gotta give me credit for that

 

So Dave, does this help ??? If you have more questions let me know !!!!!!!!!!! 

 

John T Tooooooooo long retired EE and rusty but believe this is still true

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Well. Apparently, the campground I was in is owned by the City of Manistique, Michigan.

Anyway, I called today about our site and was told that an electrician had been to the site and found no problem. I asked if the outlet was tested under load but the person at the park said they did not know but that the electrician was coming back to do another test. I again told them I thought the site could present danger to person or property and that the problem could be an open or floating neutral. The park employee told me that they had another party in the site the last two nights and they had no problem.  I again started to wonder whether the problem could be in our unit. So I moved from the 30 amp site in the campground we are staying to a 50 amp site. I ran the air, water heater etc.. No problem. None. The voltage on each side of the leg at my panel were 123 and 121. Ground to neutral was less than 1 volt.  So assuming it is a problem in the park why would other campers not have an issue?  My load is not balanced as most things run through the subpanel to the inverter. I am questioning whether a real licensed electrician inspected this or a city employee.

Anyway, any thoughts?

On another note. We prepaid 9 days in advance at 40.00 per night. They will not give us a refund or allow us to move to another site but they are renting out our site to others while we wait for them to find the problem. I have never experienced such a policy so I have more fights ahead of me.

 

Dave and Lana Hasper

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"

20 minutes ago, Daveh said:

So assuming it is a problem in the park why would other campers not have an issue? 

It depends, usually they will only notice if they use a protective power monitor on their entire incoming service, or have some equipment like you which has built in protective power monitoring and auto shuts off in this situation. Without the builtin power monitoring circuit, things appear to work normally, although its a serious safety issue.  I've seen many RV parks and boat marinas wired by inexperienced electricians, that have this issue. I always used a Progressive power monitor on my RV and my live aboard sailboat has one builtin. I bet I've been told more than 6 times, "no one else has a problem plugged in here and we havn't changed anything in years". Well that red light there and that alarm you hear beeping, says you do have a wiring problem.

Jim

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3 hours ago, Daveh said:

So assuming it is a problem in the park why would other campers not have an issue? 

How do you know that they do not have voltage issues but do not realize it? I would not return to that park without using an EMS of some type. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

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Whenever no one else has a problem, that just means they don’t have an EMS. When you are told that the EMS is faulty or junk, it only means we have had our worker stick the probes of his meter in the plug without a load and it had voltage. Usually the electrician is the one carrying the meter in his toolbox. At one Thousand Trails I was told that money was tight and they couldn’t go around and change all the receptacles and breakers that needed it. He had to go to town to purchase a receptacle for my site. 

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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Yea, I think we have decided we are not going back. Things are souring quickly because they are not returning phone calls.  We prepaid nine days in advance and had to leave after the first night. They are renting our site to others even though we said not too and they are refusing to give us a refund or allow us to use another site unless we pay for that site in addition to the one for which we have already paid. They say these things without a hint of embarrassment. This is getting a little ugly and I don't think we would feel comfortable back there even if the electrical is resolved.  The City owns the park, small city, so I emailed the City Manager tonight to hopefully get this quickly and fairly resolved.    Good grief. I have not encountered this before. Most private owners would just have resolved this on the spot. What is there to argue about? Your renting your potentially unsafe site to others so refund us and we will travel on. 

Dave and Lana Hasper

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Dave, if another person has no issues he may be using the 30 or 50 amp (maybe different then you used) at that  particular pedestal,,,,,,,,,,,,,,His loads L1 or L2 or both many be different then your configuration,,,,,,,,,,,,,He may well NOT have any monitors or EMS running................

 Any even half competent trained professional electrician should be capable of wiring a relatively SIMPLE 120/240 volt RV Pedestal, that's like Electrician 101 in their practice and training as compared to three phase and motor control centers etc etc. The problem is the RV park owner or his know it all brother in laws Billy Bob or Bubba (wired their garage while downing a case of beer and by golly it works, the world is full of amateur electricians I saw that over a 40 year career in the trade) may have been involved AND THEREIN LIES THE PROBLEM. Soooooooooo many amateurs and non sparkies have been electrocuted or caused others to be because they think its easy n they know it all YEAH RIGHT..........

 Investing in an EMS and NOT using that park again sounds like a good plan to me  

John T  Long Retired EE

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Update. Well the standoff continues. I called the park and they told me the electric had tested good. Spoke to the electrician and he told me that he tested voltage at panel but made no tests under load. He said he did not have equipment to test under load. So I don't feel like I can go back and they will not refund, so least yet.  We both are using the same argument that this never happened before and did not happen again after I left. The difference is that I can control the variables. I have a plug, cord and now that I bypassed the transfer switch, a direct lime to my panel.

Update. The City manager called amd said they hired a  new electrician that will test under load.

Dave and Lana Hasper

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14 hours ago, Daveh said:

Update. The City manager called amd said they hired a  new electrician that will test under load.

Perhaps this one has a current license? There are many electricians who are weak in some areas because the work they do rarely or never sees the problem. A floating neutral will not show unless under load and preferable an unbalanced one. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

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13 hours ago, Kirk Wood said:

A floating neutral will not show unless under load and preferable an unbalanced one. 

 
 

Yes, I should have mentioned the unbalanced part Kirk. Good point. I mean they should know that right, but the first didn't even know to test under load. Fair point about some electrician not seeing certain problems. We live in a specialist era or in this case a very rural one without many RV parks. The first electrician said he was not the one to do the install.  I doubt this second one is either as this is a big project.  My fifth wheel presented the system with a very unbalanced load so I hope they do the same. I might send a short email over to the city manager.

Dave and Lana Hasper

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I have run into floating Neutral of times and the usual repose for the Park is that no one else is mentioning the problem  To which I respond just how residents of the Park have an EMS to sense the problem?

In one park when failing to get a resolution, I used a 50 A to 30 A dogbone to pick just one phase and then a 30 A to 50 A to feed that phase into both legs of the trailer.  Only had 50 amps total but at least we were not flipping the EMS hourly.  You have to check the 50 A to 30 A dogbone periodically because the wire insidde the dogbone are only for 30 amps.

 

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Well, Here is my response from the new electrician.

Ok so we load tested and ground checked the hots, neutral and ground and didn’t see anything. Do you have to travel back this way? It would be nice to see what your setup is to try to replicate the problem. Also what is the sequence that you plug in can I see pics of all the ends/devices?  

I am a little at a loss for what to do. I do not have my new EMS system yet. I am a little reluctant to plug back in but at the same time I would like to get to the bottom of this.

 

Dave and Lana Hasper

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19 minutes ago, Daveh said:

I am a little at a loss for what to do.

At least the new electrician is listening. I guess you need to weigh the cost of the unused nights of camping and choose. I suspect that what he is looking for is signs of a melted plug on your cord or something of that sort. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

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24 minutes ago, Kirk Wood said:

 I suspect that what he is looking for is signs of a melted plug on your cord or something of that sort. 

 

I have been curious about this myself.  Hard to see anything on a pure black plug.

Dave and Lana Hasper

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11 hours ago, Daveh said:

Hard to see anything on a pure black plug.

To have a floating neutral caused by a power plug, it would likely be very badly melted and quite obvious. I examine my power plugs and receptacles on a regular basis. On the plugs look for discoloration of the pins from heat as well as small signs of melting around the base of them. On the receptacles, you look for a tight fit and no signs of melting or of weathered or burned contacts. I expect to replace the plug on my RV power cord every few years from the fit in some parks power pedestals. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

            images?q=tbn:ANd9GcQqFswi_bvvojaMvanTWAI

 

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Dave, it sounds like the new electrician has a better handle on the issue. To clear up a few more things and for the record here is some information for you and others.

An RV park is NOT any highly specialized or complicated issue for even an amateur or beginning electrician, its NOT rocket science as its SIMPLE 120/240 Volt Single Phase Three Wire and what they would learn if the first weeks of training. ANY true competent electrician would know there's no V = I x R voltage drop  UNLESS there's a load and current flow as 0 x R = 0 lol  Specialized more complicated electrical issues are involved in say Switchgear or Motor Control Centers but an RV park and its SIMPLE 120/240 Volt Single Phase Three Wire is the most basic, beginning and simplest part of any electricians education and experience. 

Unlike many Generators the AC distribution system in the RV park DOES NOTTTTTTTTTTTTT HAVE A "FLOATING NEUTRAL" Power Distribution System, it has a "BONDED NEUTRAL" distribution system. That Neutral/Ground Bond takes place around the main service entrance and Id say there's a 99% chance that Bond is in place and the Neutral is Bonded NOTTTTTTTTTTTT Floating. OF COURSE, that's not to say there cant be a total open or a loose/resistive Neutral conductor elsewhere in the RV power distribution system, in which case when loads are applied the Voltage (with respect to Neutral) may float all over the place and NOT remain any consistent 120 volts, and that's so even if the distribution system has a Bonded orrrrrrrrrr a Floating Neutral, as if its loose/resistive and current flows through it, there's an I x R voltage drop across it.

Regardless if there's a Bonded or a Floating Neutral distribution system here's what voltages would read.

 1) If the Neutral (a Bonded or a Floating Neutral system) was completely OPEN, there would be NO voltage from either leg to it, that's a bridge to nowhere, its like one meter on L1 or L2 and the other up in the air NO VOLTAGE DIFFERENCE

 2) If the Neutral has a loose/resistive connection (In either a Bonded or a Floating Neutral system) IFFFFFFFFFF there's a load and current flows through it, some of the I x R voltage drops across it so there's less then 120 remaining for the load. 

 Its NOT more complicated then that. V = I x R so current through a loose/resistive Neutral conductor causes an I x R Voltage drop PERIOD. No current flow, no I x R voltage drop, in EITHER a Bonded or a Floating Neutral system. Don't make it more complicated lol

DISCLAIMER this (including the terminology, definitions and verbage I use) may or may not be how it is today or how it is in your area, this  IS  how it was (among Electrical Engineers, Electricians, Electrical Contractors and NEC experts) when I practiced power distribution engineering and attended NEC training seminars all over the US back in the day and perhaps things have changed SO NO WARRANTY don't anyone have a calf now lol it may be different where you live, different strokes for different folks, that's quite possible in different locations...........

 

John T           Toooooooo long retired EE and rusty grrrrrrrrrrrr but believe the above is still true, it was where I practiced at least... 

 

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On 7/25/2018 at 4:30 PM, Daveh said:

Well, Here is my response from the new electrician.

Ok so we load tested and ground checked the hots, neutral and ground and didn’t see anything. Do you have to travel back this way? It would be nice to see what your setup is to try to replicate the problem. Also what is the sequence that you plug in can I see pics of all the ends/devices?  

I am a little at a loss for what to do. I do not have my new EMS system yet. I am a little reluctant to plug back in but at the same time I would like to get to the bottom of this.

 

As you mentioned if the AC loads are not balanced in your RV the increased (resistance) load on one leg may be more than the electrician is using to conduct the test.

It may also take time for heat (resistance) to become an issue.

If you have an idea of the amperage your RV draws on L1 and L2 this information would be helpful to the electrician.   

Other staying at the site may not load the neutral enough and for long enough to cause an issue.

A thermal (FLIR) camera is a good tool for issues like this.

2011 Cameo 34SB3

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5 hours ago, ALLOY said:

Other staying at the site may not load the neutral enough and for long enough to cause an issue.

Good point Alloy. If the loads are the same on each leg (such as say AC 1 and AC 2 in a 50 amp RV) there's no Neutral current draw, therefore, no I x R voltage drop across any loose/resistive Neutral conductor connection............Its if he uses one AC that's where a loose/resistive Neutral  (with a Floating or Bonded Neutral) is gonna rear its ugly head...............

Best wishes n God Bless all here

John T

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Okay, folks here is the update. We got back to the park in Manistique, Michigan, I plugged in the 50 amp and everything works. All voltages good.  No sign of the problem.

After we decided to come back I decided I would tighten everything electrical in our fifth wheel just to be sure (I found nothing loose).  One of the workampers, a retired farmer, saw me with everything torn apart and asked if he could help. I explained the problem and went through my whole system with him. When we got to my electric cord reel  I showed him the junction box connecting the shore cord and reel to the main AC input wiring in the trailer. All the connections were tight and everything looked good. He then said that the cord reel, which is powered by a 12v motor, had to have some kind of system in it to allow the cord to wind without everything jamming up. I did some research and could not find schematics of the, ridiculously expensive,  Shoreline electric cord power reel   (  https://www.hollandrvparts.com/product/50a-power-cord-reel-cc50d/ ) but I did find an old post from about 2004 of an RVer complaining that he had an electric power reel and that he had seen high voltages. He said he took it apart and it had brushes and contacts that held position against rings on the reel to maintain the electrical contact. He said it showed signs of wear and concluded he had a bad ground (other posters then chimed in and said "no with those symptoms you have a bad neutral"). He then bypassed the reel and had no problem.

This confirmed to me it was a possibility and another variable I could eliminate. The question remained why did I  have a bad neutral at the Manistique campsite but not at the two subsequent sites I tried. Well, one possible explanation was that the reel had bad spots and if it stopped at the wrong location the problem would show up. If that theory was correct I was playing Russian roulette each time I spun out the cord reel.  The theory explained why the park could not find the problem and why I did not see the problem again. We could have tested the cord by putting in in different locations but I never really liked the thing. SOOO, I cut the cord, wired a direct attachment back to the outlet box,  and pulled the entire cord reel.

I got here and everything works. Was that it?  I think probably but I don't know. Seems to me there are at least three possibilities.

1. The cord reel had bad contacts as discussed above.

2. The park had problems that they corrected in the course of checking things over.

3. The park still has problems that depended specifically on the loads being drawn on that particular day and the problem will reappear.

1 and 2 seem like the most probable and as much as I don't like to admit it I am leaning toward 1. I still have the cord reel so one of these days I should be able to do some testing of continuity on the neutral with the reel in different positions.

 

Thanks everyone so much for your help on this electrical mystery. Welcome your thoughts and second guessing.   Dave

 

Dave and Lana Hasper

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The EMS is a good  investment and IMO  a required investment. We have the portable progressive  EMS PT 50C been using it since 2006.It has saved us many times. Anything can be taken at any time at any place. We have been at this since 2006 and have no personal knowledge of one being taken.The PT 50C can be secured to the power pedestal.

Helen and I are long timers ..08 F-350 Ford,LB,CC,6.4L,4X4, Dually,4:10 diff dragging around a 2013 Montana 3402 Big Sky

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