Low current on my 1996 Fleetwood Bounder

If you are testing with the circuit loaded, then the problem is volt drop. If measuring the voltage on no-load then get hold of a superior instrument.

Greg Lynch

The circuit is loaded by the roof top air conditioner. When running off the generator the voltage read at any outlet is 121 v (unloaded) 120 v loaded. When running off shore power the voltage is 117 v (unloaded) 108 v loaded.

Your cord is probably too small. It's causing a voltage drop. Get a cord with larger gauge wire.

Thanks but it is a 10 guage cord which is what is required. Any other ideas?

Voltage Drop is caused by resistance, locate the source of the resistance and correct. if you un plug the cord from shore power then plug it into the generator and voltage is OK then th problem can only be with the shore power supply, possibly a bad circuit breaker or too small of a wire from the breaker to the outlet. it is also possible that the shore power outlet is fed via a step down transformer which may be too small. I would check all the wire connections back to the feed of the shore power.

I am assuming that the different voltages are ocurring while the cord is plugged in.

Check for a dirty or corroded plug both the male and female sides, also for a damaged female receptacle where you plug in. Does the problem repeat itself if you plug in in different locations? Try plugging in to a different source just to leave no stone unturned. I understand that the cord is new so that should be ok.

They sell sprays to clean corroded electrical contacts. I've also used sand paper to clean contacts and you might try a trimmed emery board to get into the contacts of the female receptacle. Don't use a metal nail file and keep one hand behind your back when probing anything electric that might be faulty so you do not accidently create a path to ground through your body.

I would guess you had to take apart the male plug in order to measure the voltage on the male side of that connection. If you didn't and pulled the plug part way out to slip the probe in you might have caused an additional voltage drop due to less than full or angled mating surfaces. Access the back of the female receptacle so you can measure on the female side of the connection with the cord.

If the cord was disconnected or unplugged from either end while running your air conditioning as a prime example there might be some minor or larger sparking that caused a carbon build up on the metal contacts that could get worse over time if done more than once and might not be so readily visible unless examined in depth. This could easily cause additional resistance in the connection. Always shut off the source of power before you disconnect any power cables.

I have often used a laser temperature probe to find parts of an electrical circuit that are overheating or just at a higher temperature than adjoining areas pointing me towards a possible fault. At one time it was just a loose screw that was causing the plastic in the recptacle to heat up to the point of smelling of burning electrics prior to actually bursting into flame. The temperature at the connector was 165 degrees. Everything else was within a few degrees of 80. The laser probe was the only speedy way to quickly find where the burning smell was coming from when faced with 30 or more terminal connections. Touching each connection until you get burned would not be my first choice. In your situation passing the laser probe over the various connections to a receptacle would be another way to troubleshoot. The problem could be the wire leading up to the connection, the connection of the wire to the terminal connector, the attachment of the connector to the receptacle.

Taking apart and or measuring the insides of live 30 amp receptacles can be hazardous to your health. If you are not 100% sure of what you are doing, get an electrician. Seriously!

Voltage drop is not only dependent on the gauge, but the length of the run. If you go to a heavier gauge it will not have as much drop.

As an example, #14 will give a 3% drop from 120V supply with 10 amps at a distance of 36.6m.

#10 will give a 3% drop from 120V supply with 20 amps at 23 m.

#8 will give a 3% drop from 120V supply with 20 amps at 37 m.

#6 will give same drop with 20 amps at 58 m.

Get the picture? A heavier gauge allows longer runs.

Typically for 20 amps the minimum cable will be #12, but that is for a short run.

Give us the length of the run and your total amps and we can recommend a cable size.

ref: CSA Table 2, and Table D3, 2006 Canadian Electrical code, Part 1.

The advice from most people was excellent, getting hot was mentioned several times.

Do not ignore this point as you might have a hot connection inside a cavity wall somewhere, which could give you a nasty fire!!

May I suggest that you do not use standard connectors, I believe in the USA, there is a manufacturer of heavy duty connectors for heavy duty cable called Hubble. I would suggest that an electrician wires a heavy duty Hubble socket to the outside of the house, using well over dimensioned cable (as demonstrated by several postings), to as near to the Motor home as possible (maybe with a meter!) and that you make up a special heavy duty cable for the last leg.....

Or if it is only needed occasionally, and there is a path or window that can be left open, just have the Hubble socket near to the fusebox with its own, over dimensioned cable and fuse....

That way, heating losses will be minimized and the voltage maxed out!!

Making foolish judgment I would say GW is correct in his thoughts, I am in the Tower Crane business some of our customers don't listen to the requirements of wire gauge, length of the cord and voltage loss..... until they have to buy a new inverter.... the manufacturer your dealing with may say that a 10 gauge supply cord is necessary but did they state the maximum length.... you have a couple choices here shorten up what you have or go to a #8 gauge power cord.

Katie,

The original post spoke of the "plug box". If this is the box the Bounder's plug connects to at the home, then your 9-volts drop is high, but expected (assuming a typical RV-type cable 35-feet long, 120-volt power, and 24-amps load). If "plug box" means the circuit breaker or fuse box where the power comes from, then the problem is also with the wiring back to the supply.

Pre-made RV cords do not normally come with wire sizes larger than #10, but you can buy the cable and plug end separately. This would allow you to make a heavier cord (#8 gauge) which would cut the voltage drop by about 40%. There is no safety or electrical code rule which would prohibit such a change.

I suspect that with the A/C running, you will find the cord warm to touch, but not hot. Considering the age of the Bounder, it is possible that there could be other problems with the A/C unit, causing it to draw too much power. Therefore, having it checked by a service technician may be a good idea also.

--JMM

It would be nice to hear if all this good advice has been put to good usage and the problems are fixed.

But of course there is the possibility (sadly) that the house burnt down and that he has no internet connection at this time.......

Please take pity on us an let us know the results up to now!!! Thanks in advance!

Thank you for your comments. The RV fortunately has not burned down, but I am still in a baffled state as to what is going on.

I have replaced the lead and plug twice and had no success with it. I have contacted the manufacturer and the wiring schematics are on their way to me. I wil be investigating the transfer relay that switches the current between land and generator power. Since the voltage when using the generator lines is as it should be I am fairly certain that it has to be from the relay to the house pole where the voltage drop occurs. The thing that has me most confused though is that the voltage drop appears to be in the cord from the motor home to the pole and that replacing it made no difference.

Your comments are appreciated and any further thoughts too. It's been in the 100 degree and better range here and being outside working on this, plus the limitations on the use of the air conditioner are making traveling difficult. Thanks again! Katie

Hello Katie,

It sounds like you are going in the opisite direction of the problem. if the voltage is low at the cord while not pluged into the motor home then the problem can not be within the motor home itself.

You were headed in the right direction to start with, continue to work in that direction and I am quite sure you will locate the source of the problem.

I once had a similar situation where I had a break in a cable I replaced it with a new cable and had the same situation, after several endless searches to determine the problem I replaced the cable again and like magic the problem went away.

The point is I knew where the problem was but I did not belive it, until I was forced too.

The art of trouble shooting a problem is keeping an open mind while observing the obvious.

...but did you seriously upgrade the connectors and the thickness of the cables/cord?

You only said you replaced it, we need to know exactly with what!

Unless you made the changes exactly as we said, I am very sure that you will not fix the problems.....

Please tell us in detail asap.

Thanks in advance.

PS. The fire would be in the house most likely, not in the RV.....unless the RVs connector is at least part of the problem......

Is there any heat being given out at places where it would be unexpected? Is any plug running warm to the touch? Likewise any terminals, sockets or junction boxes?

Your Blog is called :-

Low current on my 1996 Fleetwood Bounder.

But actually you are suffering from low voltage.......which can cause motors to overheat as well, so in the long run, you are not doing your AC much good either.....

It may seem like hair splitting to you.....

Since you know that when the generator is the power source, the voltage drop in OK, there is not likely any problem in the internal wiring in the Bounder. I do not have a good feel for the power requirements of your onboard appliances or the power cord length, but they should not be many 10's of amps, so a voltage drop of almost 8% does seem high. If you could check the voltage at the plug on your house while the Bounder is connected and drawing full power you could get an idea where the trouble is. If the voltage at the plug drops to a much lower value then something is wrong in the house wiring, perhaps someone wired to it with too light a guage from the house breaker box. If the voltage holds up there and is still low at the Bounder then the trouble is in the connectors or wire. You do not say where you measure the voltage at in the Bounder. There could perhaps be a problem between the connector on the Bounder and the circuit breaker box.

Excellent advice to aid in identifying more accurately the position of the problem. I am ashamed to say that the idea did not occur to me before......

My bet is on the house wiring if the new cord was made as thick as suggested.

We are still missing key info. How many amps, how many feet.

OK, I have a new twist!

Let's assume for a minute that the load is within the range for 10ga wire, even accounting for the cord length. Yet the voltage drop still occurs right? We have also already determined that there is not likely to be anything wrong with the wiring IN the motorhome, because it works fine when using it's own internal wiring from the generator. So, as Katie says...

• "The thing that has me most confused though is that the voltage drop appears to be in the cord from the motor home to the pole and that replacing it made no difference."

Big question here.

Did you, by chance, buy a 50' or 100' cord and, since you only needed 20', leave the rest coiled up nice and neat like a rope on a sailboat? If so, you may have created an air coil reactor! That will drop the voltage for sure; it happens all the time to contractors who have to do temporary connections and don't want to cut the wire. If you did that, try stretching out the cord in a random snake-like pile, no nice concentric rings, and see if the problem goes away!

Nope, insignificant reactance. It will be uH, since the reactance is between the wires in the cable, straight or coiled, and considering the "coil" the flux from the Hot and neutral will almost exactly cancel. 100Ft of "resistor" will be the biggest factor.

Use a splitter or "octopus plug" at the plug end of the cord so you can measure the loaded voltage at the plug, ditto at the receptacle end, and prove if it is voltage drop in the cord or not. It will also determine if the drop is occurring between the distribution panel and the outlet she plugs into if it is checked loaded and unloaded at those points.

If no plugs / receptacles are heating up (2 or 3 volts at 20 amps is a 40 to 60 watts concentrated in a bad connection, so it will be really hot if it is a bad plug), then it has to be cable voltage drop due to resistance. She mentions a "pole" she plugs into, how far is that from the house? The voltage drop could also be in that run. ( I had an old house that had trouble starting a large window AC unit. It was #14, but over 60 ft. When I pulled a piece of #10, it started like a dream.) Minimum wire size is often used in house wiring without due consideration for voltage drop from the distribution panel to the outlets.

Length of cord has not yet been given, or the distance from distribution panel to the outlet and that gauge has not been given, so we are all blowing hot air without sufficient information.

Katie, please fill in the details, it is all science after that.

Dear GW,

I know from personal experience that what JRaef describes is a very valid point. My wife made this mistake and the coil got really hot.......like the insulation was starting to melt!!!

It was on a plastic thing to coil it up on, how much metal was inside there, I do not know!! But iron or steel would have made the effect worse.....

This implies quite a loss....

With my caravan, I have two 50 meter cables, instead of one 100 meter, and we have at max only a couple of amps at worst!! No AirCon or similar!!

The reasons are simple, 1) each cord is lighter 2) Only put out what you need and throw the rest untidily on the ground......untidy being important!!

The heat dissipation of the cord (the minimum size for the amps) is based on free air circulating around the cord. If you start bundling, the amp rating drops due to the inability to dissipate the heat. By code, if you bundle 4 cables the amp rating drops to .8, 7 wraps and you are down to .7 of rated. Good reason not to neatly coil the cable!

Unless you have an iron core with a closed magnetic path and the conductors passing through this with the current all in the same direction, you just don't develop any significant reactance. This is not an RF air core reactor tuned to the megahertz range. (She is running an AC unit, not feeding the trailer power from her microwave ).

Well ... I managed to get south to a long stay campground where the source of power seems to be of the best quality of all that I encountered traveling. Now I am able to run 1 ac unit and other low current devices (lights computer etc)

Have enlisted help from an immediate neighbor that is knowlegeable in this area.

Hope that you all are still with me...

He has done some process of elimination actions and some measeurments.

Katie Voltages at Distribution box--------Neighbors Box-----delta
..........................18 amp load.............. similar load
LINE TO NEUTRAL = 113_________________ 121 __________8
LINE TO GROUND. = 116_________________ 117 __________1
NEUTRAL GROUND....= 2.8 (.1 amp)__________ 0.0________ 2.8 (may be an issue)

Katie Volts Pole Box (measured female side inside shore box)
LINE TO NEUTRAL = 114
LINE TO GROUND. = 117
NEUTRAL GROUND = 1.4

Total current is 18 amp (one ac running 15.1 amps and the remainder 3 amps of other low current devices)

NOTE - WITH shore LINE DISCONECTED RESISTANCE N TO G = 0 (measured at dist box)

Tried

disconnecting input line at onboard dist box
wired another #10 rv cord directly - shore to dist box
wired same #10 shore to generator out connection

neither effort produced a change in the above voltage readings

Is the Shore 3v Neutral to Ground Suspect ???

START - information gleaned from Online sources..

RV wiring is different than the wiring found in homes. The neutral and ground
wires are isolated in an RV. In a home they are tied together at the
service panel. The reason, homes have a bonded ground system and
RVs do not. Therefore never bond the neutral and ground together for
any reason. This will create a ground fault condition and may result in
electrical shock and/or fire hazard.

The big topic is safety mostly concerning the use of extension cords to connect your RV to a source

of power. It is always stressed that you use a proper 3-wire extension cord of appropriate size "Wire

Gage". The ground prong not only connects the RV to ground at the power source it also aligns the

other prongs as to be in proper polarity. Now one of the most important things about the internal

wiring of a RV is that the neutral wire is floating, or in other words is not connected or "Bonded"

to Ground. One of the reasons why is that if anything were making a connection between the RV's

ground and neutral circuits and the polarity of the extension cord was reversed, or that the polarity

of the source power was reversed, the RV would have a HOT SKIN condition or meaning that anything

connected to electrical ground via the wiring including the vehicle chassis the siding if metal, door

frames, etc. could be on the Hot or dangerous side of the 110-volt. This is aggravated by how well

the tires insulate the RV from earth ground. This scenario may seem a little far-fetched but Hot Skin

conditions happen and there is still a lot of backwards wiring out there

When planning any electrical switching for your RV always switch the Neutral as well as the Hot or

"Hots".

In most cases the internal wiring of your properly installed onboard Genset has its Neutral bonded to

Ground. This case the source ground "The Genset", and the RV Ground is electrically the same

END... information gleaned from ONLINE sources

start .. Katie

Again - When The Generator is powering the Coach the readings Neutral to hot is 122 no load - 120 volts when loaded with the same as above. (neutral is bonded to ground)

Thanks so much to all of you for your Help

Katie

Katie,

Are you sure the loads are what you think the are? Are you using name plate data or do you have an ammeter in the circuit? I am becoming suspicious you are drawing more amps than you think. I would also be interested in verifying what the ground current is and if you have a short to ground.

If AC units are failing you may be running higher current than you expect.

By the way, you voltages at the plug in point you are indicating 113 and 116 volts, both quite respectable. Does the voltage in the trailer match or do you have the 108 you deviously indicated.

Can you get at the connection point where the cord connects inside your trailer and verify the voltage and compare that to the plug end? Then we could see the voltage drop in your cable alone.

It is rare to have adequate volt meters and ammeters on a trailer, so I am curious to what you are using.

I am confident that the load is 18 amps total

Not using name plate information

Using a clamp on type digital amp/volt meter

The ground leg measured 0.1 amp @ 3 volts to gnd at the junction box as it leaves the coach.

The front AC unit is drawing about 15 amps (as expected)

As to your question above about the 108 previous reading...

That was taken on route south at a campground that had an inferior supply as

compared to where I am now.

Still pulling down the voltage from 122 volts (no load) to 114v (loaded)

note - the line cord plug at the box is not hot - only SLIGHTLY warm to the touch

NOTE TO ALL........................................

WITH THIS SUPPLY THERE IS NOW LITTLE OR NO VOLTAGE DROP COACH DIST BOX to the SHORE BOX

see info in my previous message

NOW..... When the load is applied The SHORE POWER BOX VOLTAGE is pulled DOWN

from 122V TO 114V

The neighbor has a similar supply and similar load and loses less than 2 volts when the LOAD is applied.

Thank you for your Questions and Thoughts

You wrote:- " note - the line cord plug at the box is not hot - only SLIGHTLY warm to the touch"

It should NOT be getting warm at all! It must remain cold at all times, so must any connectors....

- I am assuming that the whole cable is lying loosely on the ground (no metal underneath the cable) and that no part of it is coiled up anywhere -

Then the cable is too thin for your application, you need to buy a much heavier duty cable. Several people have mentioned this already........and given wire sizes too......

I neglected to add that any heat is a loss. You have found heat in the cable, therefore the cable has a loss. That is your problem. That is where the missing volts are going....

The cable (and all its connectors from the main fusebox through to the AC checked for heating) must be replaced by a much thicker one, at least twice as thick, more is better in this case, longer not.

Also it is always better to have a cable that does the job with no extra unused length. You can always keep the rest with suitable connectors (waterproof) to allow the cable to be extended when needed.....

We all have asked you in the past about thickness, I believe you never replied....we also recommended thicker, you never came back to us....you never told us the cable got warm, though we did ask you before!!!

Now you know exactly what your problem was all the time!!! Ohms law!!

Andy - the length of the cord is approximately 25ft and three strands of #10 stranded. This is a typical RV 30 amp shore cord with molded plug.

As above the voltage in the coach is (here in florida) the same as that at the shore box... so the air conditioner load is pulling down the source by about 8 volts @ 18 amps.

The heat is that of the 90 degree temperature here in florida - at night time after a light rain the line cord and plug are cool.

The cable is loose on the ground. (no coils)

I hesitate to go to a #8 type cable as the prints from fleetwood calls out for #10

and I may be masking the real problem.

Also we have used two other #10 rv type cords with no change.

Everything you wrote is between "":-

"The heat is that of the 90 degree temperature here in Florida - at night time after a light rain the line cord and plug are cool."

If the cable EVER exceeds the ambient temperature (out of the sun), your problem is still cable.

"The cable is loose on the ground. (no coils)" Good

"I hesitate to go to a #8 type cable as the prints from fleetwood calls out for #10

and I may be masking the real problem."

That is a s****d statement and is the cause of all your problems, not counting possible connector problems. This should have been the very first action, you would not have needed to go to CR4.....Many have told you this, you have just simply ignored them........!!!!

"Also we have used two other #10 rv type cords with no change."

WHAT A SURPRISE!!! Could you not draw any conclusions from that? I will say it now:- 'A number #10 is too thin, in fact "SURPRISE" = ALL #10s are too thin!!' Which is why you saw no change!!!!!!!!!

I, being a European, do not fully understand your wire sizes, but I appear to have learnt that as the number goes down, the wire gets thicker!!! If true, YOU NEED A THICKER CABLE LADY with a smaller ###!! Several other US persons told you that at the beginning of this Blog the same!!! I was never alone in saying that!!! You simply do not understand Ohm's law.....

GO AND BUY A CABLE AT LEAST TWICE AS THICK, THIS WILL HALVE THE VOLT DROP.( assuming that the length does not change, but halving the length will also reduce the volt drop by half)

A Cable 4 x thicker will reduce your volt drop to a 1/4 of what you have now!! Its just simple Ohm's law.

For simplicities sake, I have equated directly thickness with electrical resistance, the relationship is not quite so simple as I have implied here, but it is absolutely true that a thicker cable will reduce the volt drop as will a shorter cable....a cable twice as thick will probably reduce the volt drop to about a 1/4. Easier for you is probably is the rated amperage, if it is rated for twice the amps, you will lose half the volts.....

Anything that is "also" broken, will be far easier to find IF true!!!!

Think of it simply like a garden hose, the bigger the diameter of the hose, the more water can flow down it with the same pressure from the tap. If the hose was only 1/4" diameter, you would take a long time to water your garden and the pressure would be zilch!

A quick test, cut a #10 cable in half, put connectors onto it and measure the volt drop over it when your stuff is switched on, it should be around half of the previous volt drop!!! eg. if you were losing say 12 volts, now you would only lose about 6 volts!! or you would go from 108 volts to 114 volts. (assuming 120 volts nominal)

In the true friendly spirit of CR4, please be so kind as to let us know what your hair color is/was!!!

Mine is still Blonde, even at nearly 61!!! My beard is white, though it was dark red years (and years!) ago!!

Have a truly great cool (ed) day with your new, thicker and probably shorter cable!!!

Major problem finally solved......

Andy,

I think there are a couple things I can clarify on this. Please double check my analysis and see if you agree:

1) Katie speaks of an 8v drop on the mains voltage, as measured at the "shore"--the point where her RV connects to the power supply--when she compares the no-load to the loaded voltage. She says there is very little difference in the voltage under load, when measured at the shore and measured at the distribution box within the RV. When I wrote earlier about the possible size of voltage drop on a "typical" RV cable, I stated that this was for a 35 foot length and a 30 amp load. That was the longest normal size for manufactured cables; hers is 25 feet with an 18 amp load. Resistance is 1.26Ω/1000feet. So, with E=IR, Voltage drop is predicted to be 18*1.26*50/1000=1.13volts. This is in harmony with her observations.

2) We know very little about the wiring between the "shore" box and its origin. However, there are a few things we can learn from her data. Total voltage drop under load is 8v, and neutral-ground voltage drop is 3v. Therefore, either the neutral is a larger gauge conductor or the neutral is being shared with other circuits (a very common and acceptable arrangement in branch circuit wiring). In her case, the only difference between these two possibilities is that at worst, the line-neutral voltage could have a maximum drop of 10v when her 18A load is connected. The branch circuit conductors must be a minimum of 10-gauge, so if we solve for distance we have R=E/I=5/18=0.278Ω resistance for the "hot" conductor only, and the distance is 0.278Ω/1.26Ω*1000ft=220 feet to the distribution box. That is a pretty long distance for that gauge wire, because the total voltage drop is well above the amount recommended in the electrical codes.

Therefore, I would conclude differently from you. The primary problem is not within her RV or its supply cord, but in the wiring supply between the power source and the outlet box she plugs into. I do agree with you that the modest amount of voltage drop within her supply cord can be reduced with a larger gauge cable. Since Katie can only control the wiring from the end of her power cable to and within the RV, she can reduce the magnitude of any voltage drop by increasing the gauge of the cable. This would have a modest effect overall, but may be sufficient to forestall premature equipment failure from low voltages. If she were to inquire with Fleetwood, she will probably find that there is no prohibition within her warranty or within the equipment's design, against using a larger gauge cable.

She also mentions a attachment plug or cord end which is mildly warm to the touch when the cord is under load. In my experience, this is fairly common and normally not a cause for alarm. A certain amount of local contact resistance is normal, and cannot be completely avoided. What needs watching is if this increases over time or is more at some RV parks than others. Oxidation and weakness in the spring contacts can make the normal amount of contact resistance increase and cause melting or burning. Her cable is nowhere near this danger level. The human hand is a fairly sensitive but uncalibrated sensor for temperature. I would trust her ability to do a casual check with her hand perhaps an hour after she has connected to "shore" power and turned on the AC.

Finally, some have commented on the 0.1A current on the ground wire, and suggested that this indicates a problem somewhere. Unless the clamp-on meter being used is a particularly expensive or sensitive one, its accuracy and sensitivity is not much better than the 0.1A being reported. At these low currents, I have found that proximity of the meter's jaws to other conductors can influence the reading by this much. If an accurate measurement of any possible ground current is needed, the best way to do this is to take a piece of 10-gauge insulated wire about 3' (1m) long and wind it with ten loops around the jaw of the clamp-on meter, and connect it so the ground path goes through this wire. By doing this the distance from the meter to other conductors is increased, and the meter is reading 10x the actual current. I suspect that the meter reading she gets will be less than 0.2A (for an actual ground current of not more than 0.02 amps or 20 milliamps).

If we are going to "lay onto" somebody, we need to do this to the RV park owners, designers, builders, and inspectors, and not to Katie.

--JMM

OK, I understand where you are coming from completely.

If the voltage drop is before her cable then my comments were wrong, I somehow did not get that, sorry.

But I did understand (I thought) that she has had the same problem at different camping sites....or was it just one?

If more than one, then surely they do not all have the same problem........?

I read this also, and seemed to have ignored it. I suspect that the problem is the sites. After all, a common factor to all of them is the cost of doing the installation. The use of larger wire sizes also means the need for larger conduit sizes. Materials cost is a significant factor in the electrician's bid. With competitive bidding, the one who has bid to the minimum specification will get the job, so . . .

I suspect that the problem is showing up in an intermittent fashion, because the amount of voltage drop is directly proportional to the distance from the power source. Therefore, depending on which spot or site you have that visit, you can have a serious worry or nothing wrong at all. However, I believe the underlying common factor of minimum wire size is widespread due to the scenario I mentioned above.

--JMM

You could be right, but as I said earlier, ANY warming of the cable is a warning that voltage is being lost!!! Simple Ohm's law......at night with rain, the amps will be less anyway as the AC would not have to run so hard......!

AND changing the cable for another one of the same size/rating did not help.

Has she then not measured the volt drop just over the #10 cable? I though she had!!! and she was losing volts there too......maybe I misunderstood what she wrote, help me someone please?

Andy--

Apparently she did, because her post says (capital letters are hers): WITH THIS SUPPLY THERE IS NOW LITTLE OR NO VOLTAGE DROP COACH DIST BOX to the SHORE BOX. In my post #36, I show a calculated voltage drop of only 1.13v on the power cable (half in the neutral and half in the hot). You are right, power will always be lost to some extent in a wire or cable. One has to balance the factors to see if a cable with larger cores (conductors in USA) is a good idea: cost, hours of use, ease to carry, storage space while traveling, ability to assemble, manufacturer rules, amount of improvement in power, etc. Mild warming is normal; even warming of 10ºC above ambient (which would feel more than just warm) does not exceed the temperature rating of the cable.

This is an engineer's blog site and we often can reason the topic like engineers. However, the engineer's ideal answer is not always the real-world best answer. Hopefully, the "best" answer will also be a reasonable or decent answer for engineers. For her, keeping the existing cable and watching for overheating at the cord plug or excessive voltage drop because of being too far from the power source seem to be "good enough".

--JMM

If you plug into the neighbours and he into yours, what happens?

I am suspicious there is more amps being drawn or the loads are different. You have shown it is the shore outlet that is dropping volts, so it is a combination of total load and stiffness of the supply.

"The ground leg measured 0.1 amp @ 3 volts to gnd at the junction box as it leaves the coach." suggests you have a ground fault.

Try plugging in a hair blower with the AC off. Compare that voltage drop to the load of the AC. The voltage drop should be proportional.

GW..

Will do this tomorrow. and let you know...

Turned off the AC unit

Plugged in a hair dryer (high heat setting) dropped to 113 volts - similar to the air conditioner.

A Toaster oven on high heat had the same effect.

I must conclude that ANY substantial load pulls down the source shore voltage.

I just got back from my holiday in our Fleetwood Prowler(1972 vintage).

We travelled from Vancouver, Canada, to Glacier National Park, USA. Dropped down to Yellowstone, then to Craters of the Moon. We looped back past Mnt Rainier, and that was precisely what it was doing so we did not see much of the volcano. 4500km later we are home. A real bus mans holiday.

I suspect the problem is not your RV, but the supply in the RV parks. I think you have pretty thoroughly chased it down and identified it as the "shore" box voltage drop. Many of the RV sites I went to had some awfully long runs between the box and the distribution point.

Unless you measure less than 1 meg ohm between your ground and line plug I would not consider the problem being with the RV.

You wrote:-

Unless you measure less than 1 meg ohm between your ground and line plug I would not consider the problem being with the RV.

This value is considered to to be the definition of good insulation if above 1 M Ohm, eg a point of safety only......

But the extra current, even if it was down to only 1 K Oms, would only be around 120 milliamps at best (sorry worst!), more than enough to kill (which is the reason for this insulation value to be much higher), but not exactly loading up the shore box and dropping the voltage!!!!

What effect do you thing that this insulation value could have on the volt drop????? and how????

I too feel that the shore boxes have either too long a connection to the main fusebox, or the wire grade is too small or both.....as it has been said (stated) that the voltage drop is not over the extension cord, even though it does get warm!!! which WOULD imply a volt drop and therefore a power loss in my book!!!

I suspect the accuracy of the .1 amp reading. It is too easy to get a bad reading at that current level with reasonably priced clamp-ons. It is also susceptible to placement of the clamp. Another person elucidated the issues rather well.

The neutral rise above ground is quite common with long runs and high currents, since there is an IR drop in the neutral, but the ground should not be drawing any appreciable current.

Many of the circuits in the "shore box" are GFI protected, which means if there was any appreciable ground current it would be tripping. (Now that was a big assumption about the level of protection and age of installed systems!)

Personally I think Katie has been caught with high loads and poor power supply from the "shore box".

(I think we must have a land yacht to have ship and shore connections .)

I tend to agree with you and the infos suppled, which is why I proposes a "fix", but I feel that nobody understood it. It was a way to parallel two shore boxes (off the same phase of course) and with lamps to show if the phasing was fully correct!! Not a single taker!!!

Andy,

Not a single taker!!! I wouldn't touch that one even with a lineman's "hot stick". Paralleling is accepted by the code only if you are on much larger wire sizes, and not for any of the conditions we are discussing here. Splitting the load in the RV is a theoretical solution, but would void any warranty. Having two power cords would exceed the available "shore" connection points normally provided in many RV parks.

Its good thinking in terms of looking at all the possibilities, but somewhat further away than this solar system in terms of what would be workable for the ordinary people and ordinary uses Katie has.

I would agree with anyone who says that this topic has been well-covered.

John

I just re-read the original post that Katie put up, it says:-

The voltage at the plug box is 117, the voltage at the box where the cord attaches to my motor home is 108. Why am I losing voltage. I have replaced the cord and plug and still no improvement.

It is still the cable she is using if this is factually correct!!! The question is, is it factually correct?

As GW said earlier, we are still missing a lot of key infos, please answer all our outstanding questions asap please.

I am delinquent in responding to this BB as I am traveling from park to park until I get to My southern location. At that time I will be able to work on a resolution and understanding of this Low voltage problem. Mean time I am able to shut off anything unnessary and run on about 105 volts with 1 AC UNIT. Will take some accurate readings then and give much needed information. Hope by Sunday the 19th.

Thanks for your patience...

Then I think the only fix is to use two connections to two shore boxes (both on the same phase of course) paralleled to each other so that she gets less affected by the volt drop, because then it will be half of what she has now.

As a safety device, normal small wattage lamps should be placed between phase and phase, neutral to neutral. I would hope that the earths are identical, but if there is a thought that they may not be, then a lamp across the two earths as well.

If any lamp burns, that means a difference in either voltage or phase, so do not connect in parallel. if no lamp burns, and the lamps are good, then you have parallel paths from the same phase.....connect and use.