Brownout in RV But Shore Power Pedestal at 123 v each line

[scfishnman]

2018 Legacy SR340. Progressive EMS 50 indicates both lines at 122 to 123 volts but monitor panel inside RV showed 86 volts on one line and 107 on the other. Turned off fridge and both A/C units then turned off power switch in RV.

Rechecked voltage at shore power pedestal and then turned everything in RV back on. Voltages on both lines were good. About an hour later checked monitor panel and one line was below 100 volts. Pedestal still at 123 volts on L! and 123 volts on L2. Went through the same procedure again and after an hour or so brownout showed up again on RV monitor Panel.

Motor Home was purchased new a few weeks ago and has already had the Transfer Switch box replaced because of no shore power available in the RV.

Any idea on what the problem might be? It is a long drive back to the dealer.

[babock]

With a load on like an electric heater or AC, measure voltage at your fuse panel or a few outlets and see what the voltage is. You will have to find outlets on both legs.

[TimVWulp]

Sounds like you have a lose wire/wires bad connections at power cord to RV or the work they did to the transfer switch may be subpar. Be carful what ever it is does not overheat and do bad things.

Hope this helps Tim

[CHICKDOE]

sure sounds like a problem within the rv. i'd take voltage measurements at the shore power input to the transfer switch and then the output from the the transfer switch. it could very possibly be a loose connection there. the fact that both legs are affected could point to a faulty connection with the neutral. of course it could be something else, but the odds are pointing to the recent work on the transfer switch. your internal monitor panel would be after the transfer switch. you might want to run the generator and see if you have the same problem reflected on the monitor panel.

[Sealyn]

Are you in a RV park? If so it could be a problem with a neighbors rig. Had the same issue you are describing and the cause was a RV 2 spots away with a bad inverter.

[formerFR]

unplug from the 'ems' or 'surge protector' and see if the problem goes away.

[Wilco]

It sounds like a bad/loose connection somewhere in your power coming to your RV. Usually it is in one of the connections along the power cord. Signs of a loose connection is blackening or melting of the insulation on one of the prongs of a plug.

I would look for a loose connection where the power cord plugs into Progressive 50 or a bad connection inside of the plugs at either end of your power cord. Also look at your twistlock connector on the RV. Last but not least, look at the connections to your power panel inside your RV.

[TitanMike]

If there is full voltage at the power pedestal when under load but low voltage inside, my first target would be loose connections.

After seeing all the posted photo's of burned wires on the inside of the factory installed power entrance connectors that would be my first stop.

Unless the installers are using preset torque "screwdrivers" to tighten the screws they can range from finger tight to thread stripping tight.

I would make sure that first there is no burning or corrosion at these terminals and if so, correct the problem. May take replacement of the power entrance socket. Also check both ends of cord after voltage drops. If connector on either end is hot, cord may need to be repaired or replaced.

[CedarCreekWoody]

Note that all suggestions say to check the voltages UNDER LOAD. Voltage can check out fine but then drop dramatically under load if there is resistance on the line.

[dbledan]

I would bet that either wiring at one of the connections or the breaker box is poor connection.

I would unplug from the EMS backwards checking the plugs for a good connection and burnt prongs. While power is off I would also pull on wiring at the breaker box to check for firm unburnt connections and that all the terminals are screwed down appropriately.

Once all that checks out you can break out your meter and check things under load as well, but this will prevent sparks from any lose wiring that may be found.

Good luck and stay safe!

[Photo Lab]

[QUOTE=scfishnman;2104571]2018 Legacy SR340. Progressive EMS 50 indicates both lines at 122 to 123 volts but monitor panel inside RV showed 86 volts on one line and 107 on the other. Turned off fridge and both A/C units then turned off power switch in RV.

Rechecked voltage at shore power pedestal and then turned everything in RV back on. Voltages on both lines were good. About an hour later checked monitor panel and one line was below 100 volts. Pedestal still at 123 volts on L! and 123 volts on L2. Went through the same procedure again and after an hour or so brownout showed up again on RV monitor Panel.

Motor Home was purchased new a few weeks ago and has already had the Transfer Switch box replaced because of no shore power available in the RV.

I read through the existing posts, and thus far nobody has mentioned the possibility of BOTH sides of the 50 amp pedestal receptacle being wired to the same side of the supply. Check between both lines, and you should have a voltage on the order of 250 volts, or specifically line 1 plus line 2. If this checks out OK, my bet would be a bad neutral connection. This is a too common case with sloppy assembly (loose connections) and/or cheap connectors. The ones typically used by RV manufacturers are low end for a reason, although sufficient for the purpose, unless there's a problem with corrosion or a loose screw at a connection. Personally, I prefer Hubbell brand, as they will easily handle an overload if need be, and have really secure connections for stranded wire. A bit off topic...I would never use solid wire in a vehicle, as it invites failures down the road. I use marine cable, which is stranded, and the wires are tinned to resist corrosion. It is only costly once.

[Grumpy7159]

I would start at the transfer switch. With all power off check the connections and look for signs of overheating. If there is heat being generated and you have a dissimilar metal at the connection (copper to aluminum for example) over time the connection could loosen up. just my 2¢ worth.

[Tom48]

Does the house run well on the generator?

[scfishnman]

Thanks for the suggestions. I have tried all ideas presented with no success. Forest River Tech support contractor and the dealer had no different ideas.

Connections are tight, no indications of anything charred, connections read the proper voltage at all points in the transfer switch. Storage facility owner has had electrician check all power pedestals which are new.

What I have learned is that brownout reading on the monitor in the coach (mine is the Precision Circuits Touch pad) will not change when the proper power returns unless the double 50 amp circuit breaker is cycled off/on OR the reading on the monitor touch screen is pressed. Then it reads the current power. In other words the Precision Plex touchscreen monitor continues to display the error until the monitor itself is reset. So, the brownout condition is a transient one. When I leave the coach in the storage facility, the rear A/C and the refrigerator are left on. When I return they are working but the monitor is reading brownout on one line. I have been checking every day with the same result.

I have the Progressive 50 Amp EMS at the shore power pedestal. It is supposed to shut down the line if a brownout occurs and then continue to provide an error code along with the "no error code" once proper power level returns. When the brownouts occur on my coach there is no error code reported on my Progressive 50 Amp EMS which makes me suspect that the problem is somewhere in the coach's electric system (could be the monitor reading or something more serious) rather than the storage facility's circuit.

To me the issue really is protection of appliances. I have not been able to determine if the coach EMS will shut down appliances when there is a brownout.

Anyone know if the Precision Plex control System in the coach shuts down appliance on a brownout line. I know it will shut them down in a priority order to avoid a system overload tripping a circuit breaker.

[Photo Lab]

Sounds like a transient voltage drop, since your line protection doesn't show a problem; probably due to there being a delay built in to avoid shutting you down when a very brief voltage drop occurs, such as when an A/C starts.

On the other hand, it seems to me that the PP monitor is not designed with "real world" conditions in mind, considering that it retains an error code "forever" even though the drop was apparently nearly instantaneous. I would personally worry more about sharp voltage spikes than temporary droops. And, I might suggest that nearly all modern electronics are built to run off a low voltage source, anywhere from 5 to 24 volts as a rule, and the power supplies almost invariably are designed to operate from line voltages from 100 to 240 volts without adjustments.

[Iwannacamp]

Color me stupid, but I didn’t see anywhere where you used a meter to check the voltage.

Unless I’m drunk the EMS measures in...not out. It has a contactor built in that can cause all the symptoms.

As stated a bad connection is most likely the issue. Where is the problem.

I know nothing about transfers so I am out there.

We need an engineer...he will be along directly.

[CHICKDOE]

it is true that the EMS measures the input voltages and connections. it does not know what is going on after it passes power to the output side. the fact that it is not showing a prior error seems to indicate that it did not see a voltage drop of the magnitude being displayed on the power panel. of course if it was a transient it might have been of such a short duration that it did not have time to react.

i am not aware of how the power panel works. does it display the instantaneous voltage or does it 'freeze' and display a lowest voltage encountered since the last reset? also where is this power panel installed? is it in the shore line before the transfer switch or in the line from the output side of the transfer switch? this might help diagnosing where any potential loose connection is?

[ScottBrownstein]

Does the problem continue to appear if you run without the EMS? It does have its own contactor and would be nice to eliminate it totally as a source of problems. Besides, your pedestal seems to be stable.