Automatic Transfer Switch Replacement

Odometer: 60,067

Replacement Date: 6/19/2020

As with other projects in the 2008 Newmar KountyStar 3916 KSDP section of our site, I am documenting for fellow owners what we did to make repairs on our coach.  This is for documentation purposes and does not represent being a how-to guide.  In this particular repair, there are dangerous electrical voltages involved. 

While the repair is rather simple, if you are not comfortable with electricity you should not attempt to do this yourself and should have a qualified RV electrician do the work.  You should not be charged more than 1 hour for their service to do this job, if they are charging you more than that they don’t have a clue to what they are doing!

This old Progressive Dynamics ATS 5200 (automatic transfer switch) has two inputs and one output. The replacement part is the same, except the case was different. The output goes to the coach inverter (in our case a Mangum Inverter.) The two inputs are commercial shore power, which is protected by a Surge Guard and the other is the generator’s output. When the generator A/C is stable and present it will then switch the breaker from shore to generator automatically.


Issue Diagnosis

We have noted since the delivery of the coach at the time of purchase the transfer switch would not always work.  The generator would start and then the automatic transfer switch (ATS) would attempt to transfer power to the generator.  It would often fail and then it would cycle through this until it stopped trying altogether.  The generator would just run at idle and the ATS would not try to transfer  Other times it would work without fail.  We had this looked at by the shop twice and neither time would it fail, hoping the extended service warranty would address the cost.  This problem would happen both under electrical load and no load.

The first, and least cost, step to address the issue was to replace the transfer switch and then if that did not work we would look at the Onan (Cummins) generator that is in the front bay.  The repairs on the generator would likely be much more expensive.  As it turns out we were able to address this problem at half the cost of our service contract’s deductible would have been and because Jason is comfortable with this work we had no labor to pay for this.

Replacement Part

The replacement part has a slightly different number from the original and we purchased it for about $152 on Amazon Prime.

Progressive Dynamics PD52V 5200 Series Automatic Transfer Switch – 240 VAC, 50 Amp

The replacement part has virtually the same footprint and is wired in the same manner as the original 2008 unit.  The new unit required “knocking out” larger cutouts on the bottom and the screw pattern for mounting was slightly different.  This only added about 5 minutes to the replacement.

The original replacement part was defective, one of the lugs broke right off when I was loosening them to open the cable pinch point inside.  I returned the part through Amazon Prime with zero issues.  We received both of the units in just 2 days from Amazon and the return was no cost.

Our transfer switch does not have the surge protector built into it, we have a Surge Guard upstream from the ATS.

Original Part

The original part was a Progressive Dynamics 5200 ATS (Automatic Transfer Switch) mounted in our electrical bay on the driver’s side of the coach.

As is noted on the cover, 120/240 volt power may be present, handle with extreme care.


The replacement process was very straight foreword as the replacement part is nearly identical to the original part.  Again, this is NOT a how-to guide but this is what I did to replace the transfer switch.

  1. Ensured power was removed from the shore power.  I could see the end of the cable and I was sure no one could plug it in while I was working on this.
  2. Turned off the automatic generator start feature of our Magnum Inverter, to prevent dangerous power from appearing out of nowhere from the generator.
  3. Turned off the circuit breaker on the generator, as a double-check.
  4. Turned off the main breaker in the bathroom for the coach to ensure there was no inadvertent back feeding from the inverter. (you could (should) also power down the inverter)
  5. Documented with photos all of the cables in and out of the box, including the hidden chassis ground wire that came up and under the box to the left side of it.
  6. I loosened all of the individual cables from the switch and I removed the washers that secured them to the box.
  7. I “knocked out” the bottom cutouts for the larger diameter wire guides that our coach uses for the shore and generator source power.  The top of the box was already the right size.
  8. I removed the box with the 4 screws that were holding it on the wall of the bay and then installed the new box with 4 new screws to the new pattern on the wall of the bay.  The wall is just particle board with carpet glued on it, so it was easy to put back in place job.
  9. I then screwed down the individual color-coded wires to the original lugs as documented earlier.
  10. I double-checked my work with a continuity tester that there was no cross over caused by misplaced strands on the wires.  As well as there was continuity from the inverter main through the ATS to the sure guard, etc.
  11. Having a fire extinguisher handy, I plugged the coach back into the main power and waited for the surge guard to activate the power.
  12. Turning on the main breakers and double-checked for power inside, inverter/charger was happy, etc.
  13. I reset the generator circuit breaker and started the generator from outside (using the controls on the generator.)
  14. Verified that the transfer switch went over to the generator and there were no issues!  After 6 months now we have used it numerous times while parking off-grid overnight.

After having to do this process twice, because of the broken lug, the second time went much faster. As I noted earlier, an RV repair shop should be able to do this with no more than 1 hour of shop time.

The original Progressive Dynamics 5200 ATS Wiring Diagram, the new one is the same. The key is to not change the individual wires from the original to the new switch, keep them all landed on the same screws.