Voltage Drop - NOT Park Problem

[ThruTraffic]

Phoenix Cruiser 2551 30a service

- First noticed it when A/C turns on then stumbles. Voltage at another RV outlet dropped well below 100. Capacitors good. A/C working fine until this point. A/C did trip ITS 20a breaker one time. 30a main held.
- Problem persists when disconnected from shore power and generator running. Main indicator this is an RV wiring problem not shore power delivery system.
- Thermostat threw an E1.
- Inverter monitor behind driver seat threw an E2 and E5.
- Can turn on toaster at one outlet voltage drops 3v
- Can turn on hot water heater voltage drops 3v
- Hooked up a 15a draw elect device drops 5v
- System wide problem
- Checked connections at transfer switch, socket for shore power, junction where old EMS used to be, mains in RV breaker panel. Checked neutrals, grounds and feeds. All tight.

Shore power is my RV lot shop. I can find no voltage issues there even under load. Problem is on the load side of the RV sidewall shore power connector. Even tried different cables and installed a new 30a breaker.

Am I missing any 120v main connections in the RV not listed above?

I’m stumped.

[Dusty_R]

Maybe try a heat sensor, and check the entire path that the current will flow.

[time2roll]

wnjj wrote:
I think this was mentioned earlier but you need to put a decent load in the RV then measure the voltage at every possible place you can between the source and load. You’ve said the voltage is good at the pedestal and bad at the load. This means there is a resistive connection somewhere. While under load, measure the output side of the breaker the load is connected to in the RV panel. Then measure another one to eliminate the breaker and wiring to the load. Next move upstream to the feeder line, transfer switch, etc.

The problem will be between the last “good” voltage and first “bad” one.

Yes keep poking around until most of the voltage drop is found. Should not take more than a few minutes once there is access. Tightening a connector is not proof that it is functioning... need to measure.

Hard to tell what the error codes are saying without the owner's manual.

[wnjj]

I think this was mentioned earlier but you need to put a decent load in the RV then measure the voltage at every possible place you can between the source and load. You’ve said the voltage is good at the pedestal and bad at the load. This means there is a resistive connection somewhere. While under load, measure the output side of the breaker the load is connected to in the RV panel. Then measure another one to eliminate the breaker and wiring to the load. Next move upstream to the feeder line, transfer switch, etc.

The problem will be between the last “good” voltage and first “bad” one.

[joebedford]

ThruTraffic wrote:

wa8yxm wrote:
Glad to see you found the problem.

Uhhhh, I haven't found the problem.

Talk about not reading posts ....

[ThruTraffic]

wa8yxm wrote:
Glad to see you found the problem.

Uhhhh, I haven't found the problem.

[wa8yxm]

Glad to see you found the problem.

Just today I was talking to another person with training not unlike my own.

I mentioned that when my RV was new I had issues with the A/Cs sometimes one worked .. Sometimes the other. both or neither.

Started at the breaker box (Stopped there too) one screw took over THREE FULL TURNS before it was tight.. They stuck the wire in.. Forgot the screwdriver it seems.

I went through every screw in the box.

My Favorite RV-Girl (her license plate. She's a mobile service technician) confirmed.. Common issue.

[ThruTraffic]

bob_nestor wrote:
I once had a similar problem but I see you stated in your original post that:

"- Checked connections at transfer switch, socket for shore power, junction where old EMS used to be, mains in RV breaker panel. Checked neutrals, grounds and feeds. All tight."

... so I'm not sure if this helps any, but...

The source of my problem was in the main RV breaker panel. Even though all the connections were tight I discovered that someone (at the factory) had cross threaded the screw holding the neutral line in the box. (Things worked for for a few years, then I had power issues.) The screw was tight but hadn't been holding the wire very well and over time the connection degraded with a patina build-up similar to what happens in the contacts in the transfer switch. I had to remove and replace the small bus bar the neutral was attached to and that fixed my problem.

I pulled a new feed from the t-switch to the breaker panel so no patina on the main feed. I didn't replace the neutral buss but I did re-seat all the neutral and ground terminals and even bonded the neutral and ground buses and that made no difference. (bonding removed now).

The only thing I have not replaced is the breaker panel. 🙂 I really can't see how that would fix anything but at this point I'm not discounting divine interference. LOL

[bob_nestor]

I once had a similar problem but I see you stated in your original post that:

"- Checked connections at transfer switch, socket for shore power, junction where old EMS used to be, mains in RV breaker panel. Checked neutrals, grounds and feeds. All tight."

... so I'm not sure if this helps any, but...

The source of my problem was in the main RV breaker panel. Even though all the connections were tight I discovered that someone (at the factory) had cross threaded the screw holding the neutral line in the box. (Things worked for for a few years, then I had power issues.) The screw was tight but hadn't been holding the wire very well and over time the connection degraded with a patina build-up similar to what happens in the contacts in the transfer switch. I had to remove and replace the small bus bar the neutral was attached to and that fixed my problem.

[MEXICOWANDERER]

Gotta be smarter than the problem...

Get a temperature reading point and shoot gun

Load the system down to replicate

Trace the system with the thermal reader. It would be impossible to get high resistance Voltage drop without A LOT OF IMPOSSIBLE TO MISS HEATING.

Pay close attention to junctions, fuse panels and busses.

[joebedford]

Since the problems are the same on shore power and generator power, I'd guess relays inside the transfer switch but you replaced that so it's not that. Broken wire inside insulation or bad connection of a lug to wire.

[prichardson]

When checking connections, did you put a screwdriver to them to make sure they were tight and clean? What is the condition of the contacts and connections IN the transfer switch? The problem may lay there.

[ThruTraffic]

Here's an update:
- Problem persists.
- Moved RV to different site feed (site is where I park my RV most of the year fed off a 200a 240 v service in a 50x50' shop. RV is the ONLY place a voltage drop appears. I have a 100a feeder to an RV pedestal outside for summer and an RV plug inside for winter that is ~3' of #10 wire from the main 200a panelboard.
- Replaced the shore power cord with a new one 25 feet shorter.
- Replaced transfer switch.
- Replaced the shore plug to t-switch feeder.
- Replaced the t-switch to main panel feeder.
- Old EMS junction no longer in circuit.
- Took inverter off line; disconnected runs and jumpered the two breakers it used).
- Disconnected the charger.
- Replaced the main breaker.
- Released and retightened all breaker panel terminals.
- I even get the same voltage loss with the neutral bonded to the ground in the breaker panel.

FYI I spent 20 years as a lineman and a residential/commercial electrician so I have a bit of a clue what I'm doing. I'm not above mistakes and errors in this field but they're pretty rare. Every time I made a change I retested for the problem and each time the results were the same; unacceptable voltage loss.

So, I've pretty much rewired the RV so I'm going to have the power company come cut the seal and pull the meter so I can tighten the main lugs on the service and main panel. I can't find anything currently that points to that being a problem but aluminum wire/lug connections are known to loose up over time but not normally in the short time this service was installed.

If the panel lug task doesn't resolve it I'll have the power company check the transformer and underground lateral for problems. They just a month ago replaced the main primary through here and I've noticed since they energized it there is a 4 to 5 voltage variation under no load throughout the day.

That said I've seen no evidence it's a building or service issue. I have a friend who stays a couple of times a year. He saw no issues plugged into the same pedestal I was although in hindsight his rig is 50A, 240 volt. It's possible he would not see a loss but that would be a weird set of wiring coincidences I think.

[ThruTraffic]

valhalla360 wrote:

ThruTraffic wrote:

From initial post : Problem persists when disconnected from shore power and generator running. Main indicator this is an RV wiring problem not shore power delivery system." If I took the rig to Walmart's parking lot and ran it off the generator and still had the same problems would one believe it was shore power?

Did the generator handle the air/con in the past without problem?

Otherwise, tracing the voltage from the entry point of the RV to the air/con is the logical process to find the issue.

Another quick verification is can a neighbor plug into your pedestal and verify their air/con comes on without problem?

Yes
Done
Done


Please note people: This is NOT an A/C problem. A/C circuit is disconnected. A.C was just an example VICTIM.

[ThruTraffic]

marty1300 wrote:
I had a 120 volt issue a while back. On shore power all was well. On generator is where the issue was. From our generator to where the transfer is made (manual transfer). There was a junction about 3 feet away where the stranded wire from generator was spliced into the solid wire that would go to transfer plug in back compartment. Look in a compartment near generator you may have same scenario. My wires had come apart an eventually burned.

No junction. Straight shot from shore plug to transfer switch (which I replaced.)

[valhalla360]

ThruTraffic wrote:

From initial post : Problem persists when disconnected from shore power and generator running. Main indicator this is an RV wiring problem not shore power delivery system." If I took the rig to Walmart's parking lot and ran it off the generator and still had the same problems would one believe it was shore power?

Did the generator handle the air/con in the past without problem?

Otherwise, tracing the voltage from the entry point of the RV to the air/con is the logical process to find the issue.

Another quick verification is can a neighbor plug into your pedestal and verify their air/con comes on without problem?