Voltage Reading Different at Post and In Coach

[raibourn]

I have a 2017 Thor Aria with built in surge suppressor and have an additional suppressor to plug into the post and then plug the power line into that suppressor.  The voltage reading on the outside suppressor reads 119 to 122 so apparently not a problem.  However the firefly system in side the coach shows a transfer switch fault with incoming readings of 129 to 133.  I believe the fault can be caused because of the high readings inside the coach.  Any idea how the readings can be so much higher inside the coach than at the post?  Any help will be greatly appreciated.

[wolfe10]

Assume this is 50 amp service.

And, only way for voltage to be HIGHER in the coach (vs false reading) is for there to be a problem  with the neutral. 

First thing I would do (with shore power off, generator off and inverter off) is open the ATS and also the box where shore power cord come in and make sure all connections are clean, tight and not burned.

[hermanmullins]

Agree with Brett with one exception. I would start with your Cable. With it disconnected check all pins for corrosion (arc burns) caused by plugging in and unplugging with power on. I had the same issue at my home and found that the cable was the culprit. Cleaned the Male Plug and the power was back to level and even on both legs. Easier to start with the simple items first.

Herman

[desertdeals69]

You might verify the readings by using the same voltmeter at each location.

[bm02tj]

You need to test  L1 to L2 then each to neutral at both locations 

if you or park has a neutral problem you get a voltage imbalance 

[manholt]

In your case, the problem is either as Brett or Herman said.

[raibourn]

Thanks for the input.  I took the issue to Camping World (that is where I bought the RV).  They said they could see the problem but could not tell how to repair it and that they had talked to the manufacturer whose only suggestion was to change out the Automatic Transfer Switch (expensive) and see if that would work since there was no way to test the system.  Fortunately for me, they did not have the part.  I then decided to call Southwire Company, the manufacturer of the switch.  I talked to one of their engineers who told me that he doubted that the switch needed to be replaced and suggested that it should be recalibrated.  He emailed me the instructions which I followed and the problem went away.  I have been checking for a couple of weeks and everything if as it should be.  Hope this helps others with the same problem.

[txiceman]

If you have a power cord winder, it may be the problem.  The slip rings in the winder could be dirty or pitted.  It is job to pull the power winder down and check the slip rings.

 

Ken

[bm02tj]

1 hour ago, raibourn said:

Thanks for the input.  I took the issue to Camping World (that is where I bought the RV).  They said they could see the problem but could not tell how to repair it and that they had talked to the manufacturer whose only suggestion was to change out the Automatic Transfer Switch (expensive) and see if that would work since there was no way to test the system.  Fortunately for me, they did not have the part.  I then decided to call Southwire Company, the manufacturer of the switch.  I talked to one of their engineers who told me that he doubted that the switch needed to be replaced and suggested that it should be recalibrated.  He emailed me the instructions which I followed and the problem went away.  I have been checking for a couple of weeks and everything if as it should be.  Hope this helps others with the same problem.

Can you post the email as I would like to know about this 

Thanks Bruce 

[raibourn]

Here are the three files provided by Steve Guarcello at Southwire.  Hope this helps!

40250-RVC Calib Apr 18 2012[7214].pdf Steve's Tip 2 Pedestal V Ck 50 Amp[7192].pdf Steve's Tip 3 ATS V Ck[7193].pdf

[bm02tj]

Thanks now I need to find  out how this works 

Bruce 

[raibourn]

In addition to the files, I asked the two questions as outlined below with the answers received from Southwire:

Two questions:

 

1. These instructions read for a 40250-RVC, mine is a 40350-RVC.  Are the instructions the same for both models?2 in the instructions about the calibration calls for an appropriate “jumper”.  I am not sure what this is.  An insulted wire of the appropriate size plugged in to each side of the J8?  Thanks for clarifying

The instructions are the same for both units.

 

You can use a wire if you want.  However, there is a jumper installed on the two pins in J12.  You can remove that jumper and use it.  Just remove to put it back when you are done.

You can use your generator for recalibration power as long as the generator is producing 120 volts.