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Old 11-08-2019, 03:04 AM   #1
Senior Member
Mo_Mike's Avatar
Brand: Thor Motor Coach
Model: Vegas 25.2
State: Missouri
Posts: 1,038
THOR #4687
Automatic Transfer Switch wiring issue

I have already experienced the "loose connection" and "loose wirenut" issues causing melted wirenut caps and burnt connections, so I check the connections every month during the summer...

Now though, I have experienced a new "issue". I fired up the generator and found no power to the outlets. Traced the issue to the ATS. Found a melted wirenut cap, however the connection was still there, but the wire had basically "burnt". The wire coming from the generator was a normal ROMEX solid copper, however, the wire coming from the ATS was a stranded wire that didnt even look like copper. Not sure if heat had caused the copper to discolor, however, the stranded wire was now a silver color.

I just wondered if anyone else had found issues with this area of wiring, and shouldnt the wire from the ATS also be solid copper?

Not even really sure why the short stranded cable is there, as it is only about 18" long and I think the generator copper wire could be wired directly to the connector on the ATS...

It is below freezing out today, so didnt go out to investigate, and a new wirenut got us on the road earlier in the week, but want to correct this before the next trip..

2016 25.2 VEGAS with 2017 Jeep Wrangler AND Two Dogs; Norwegian Elkhound & Morkie (The RV is actually the Dog's)
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Old 11-11-2019, 07:11 PM   #2
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Brand: Thor Motor Coach
Model: 2013 ACE 30.1
State: Alberta
Posts: 1,410
THOR #2631
I see no responses to you so far. The fact that the wire nut had melted is a sign of an overheating connection which is likely caused by either a poor electrical (high resistance) connection or the current draw is too high through the connection (overload). Sometimes stranded copper wire is tinned so it looks silver which helps to prevent copper oxidization (exposure to air causes copper to oxidize over time). Do the other ATS connections look silver when you remove their corresponding wire nuts?

Stranded wire also tends to lose individual strands when wire nuts are turned on and off many times......which can result in fewer conductors physically carrying load current (if enough strands are broken off). The gauge of both the copper gen feed conductors and the stranded ATS conductors that mate to them should be the same. Since twisting solid copper to stranded copper always seems to result in the stranded wrapping the solid, ensure that there is adequate stranded wire to wrap the solid a few times (twist together clockwise of course) and then put on an appropriately sized wire nut for the conductors being joined. You also could try the appropriately sized “set screw style wire nut” which consists of an outside threaded metal collar that physically goes over the twisted wire pair and then the set screw on the coller tightens down onto the conductors. A plastic wire cap screws onto the external collar threads. These should not vibrate loose like a regular wire nut also makes inspections easy and does not cause damage to the captive wire splice, especially if stranded wire is in the mix.
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Old 11-12-2019, 03:45 AM   #3
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Brand: Thor Motor Coach
Model: 2020 Thor Outlaw 29J
State: California
Posts: 29
THOR #16597
I don't know if this is related, but my 2020 Outlaw was built in August, I purchased it in September, and I got a recall in October for a loose connection between the battery cable and the Battery Isolation Manager or Relay that could cause premature failure and possibly cause a fire.
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Old 11-12-2019, 12:09 PM   #4
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Brand: Thor Motor Coach
Model: 2020 Magnitude SV34
State: Florida
Posts: 4,131
THOR #12751
From my perspective, higher current wire connections should be directly connected versus using wire nuts.

On my Outlaw 29H the 30A Transfer Switch used wire nuts, which I checked to make sure they were wound properly and secure.

My 2020 Magnitude with a 50A Transfer Switch uses solid connection points that are tightened down with screws and no wire nuts.

During manufacturing they many times they just hold the wires together and twist the wire nut. I recommend checking every wire nut at every junction in the rig to make sure they are properly secured in the wire nut. There have been dozens and dozens of reports on here where people found melted wire nuts and wires because of poor connections.

I did find in my 2018 Outlaw 29H, they eliminated many of the wire nuts for the 15A and 20A circuits and used WAGO Connectors that were very secure and much better than a wire nut in my opinion.
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Old 11-12-2019, 01:30 PM   #5
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Brand: Thor Motor Coach
State: Florida
Posts: 1,241
THOR #1249
javelin is right about the stranded wire being cut with the wire nut. The easy solution is to remove all the stranded wire pigtails from the ATS and wire the romex solid wires directly to your ATS. All you need is a pair of needle nose pliers to round the ends of romex and live meldown free.
Former owner of 2015 Thor Vegas 24.1 in Ocala
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