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05-28-2020, 09:31 AM
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#1
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,321
M.O.C. #17894
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WARNING Burnt up water heater junction box
Went camping over the memorial day weekend. Upon set up (with water heater full) I turned on the 120 volt heater switch and left it on.
On sunday, I smelled something strange but could not figure out what it was. Got up Monday morning to take a shower and no hot water. Thinking maybe someone turned of the switch, I looked, its still on.
I go outside and pull the little black switch out and check for power, no power present.
I go inside and take apart the cabinet consealing the heater. Found a junction box whitch is mounted to the heater case from the outside. Just barily touched it and got a small fireworks show. To remove the cover the box has to come off.( Bad design )
I Turned off the power at the panel and removed the box and its cover and found a burnt of mess.
In the box is a 12 volt relay that switches on the 120 volt heater from the switch panel.
Unit still worked on propane so I said I would fix it when I got home.
I decided to abandon the 12 volt switch in the switch panel and hard wire it to the bathroom wall by the sink. I used a pilot lighted switch so you can tell it is on.
Had to cut a few access holes in the underbelly to do it.
Wired it so the little black switch still functions as a fail safe and must be on for the wall switch to power up the heater.
Just a guess, but I think a loose conection from heating up and cooling down over time was the cause. ( another bad design IMHO ). Tried to post pics, but cant figure out how to.
Not saying you all should tare your unit apart to look but be aware of any odd smells and act quickly before disaster happens
__________________
2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch. 5 step glow steps
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS
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05-28-2020, 09:34 AM
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#2
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,321
M.O.C. #17894
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Figured it out. LOL
__________________
2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch. 5 step glow steps
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS
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06-02-2020, 08:46 PM
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#3
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,321
M.O.C. #17894
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No response's ?!!! I find it hard to believe that no one is concerned about a factory wired water heater that has the potential to catch fire and burn your unit to the ground with you and your family in it.
__________________
2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch. 5 step glow steps
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS
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06-02-2020, 09:04 PM
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#4
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Montana Fan
Join Date: Oct 2015
Location: Round Rock
Posts: 475
M.O.C. #17905
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I appreciate your post letting us know what you found. I think this is the first posting I have seen with this problem. Good catch. Not sure where that box is on my model. I may take down the wall in the pass-thru just to see if it may be visible from there. Looks like it took 9 years for the problem to develop. Lots of bad roads and bridges to shake that connection loose. Thanks for the heads up.
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Pete & Joan & "Honey" fur-baby.
2015 Montana 3611RL 2012 F350 6.7 DRW Lariat
Disc Brakes & Sailun 14 ply S637
6-pt Hydraulic leveling
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06-02-2020, 09:59 PM
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#5
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Montana Master
Join Date: Mar 2015
Location: West Richland
Posts: 1,253
M.O.C. #17164
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Were there any wire nuts in your junction box? My unit almost burnt down do to poor craftsmanship on the wiring from my factory installed generator. Lucky thing Keystone put metal junction boxes in our units. I kept smelling burnt plastic and thought the generator was overheating, nope all the 110v wires and wire nuts melting/burning. Junction box was so hot it burnt my fingers when I touched it. Only thing left of the wire nuts was the little metal inserts.
Glad you found the problem before you had flames.
Tom Marty
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06-03-2020, 05:32 AM
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#6
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,321
M.O.C. #17894
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Yes they were wire nuts connecting the leads from the relay to the hundred twenty volt feed to the water heater. I suspect that's where the issue was.
__________________
2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch. 5 step glow steps
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS
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06-03-2020, 05:32 AM
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#7
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,321
M.O.C. #17894
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That was supposed to say 12 volt
__________________
2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch. 5 step glow steps
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS
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06-03-2020, 08:04 AM
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#8
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Montana Master
Join Date: Oct 2006
Location: McKinney
Posts: 7,177
M.O.C. #6433
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Odd, I check the forum for new posts regularly and did not see your original post. Maybe that is why no one else commented on it.
But you are not the first to report burned wires in that J box. Has been reported several times over the years after water heater stopped working. Often it was the neutral wires that burned due to bad wire nut connection.
__________________
Bill & Patricia
Riley, our Golden
2007 3075RL (recently sold, currently without)
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06-03-2020, 08:40 AM
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#9
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Montana Master
Join Date: Oct 2019
Location: Hesston
Posts: 735
M.O.C. #25060
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I'm no electrician, but how do the wires in the junction box get hot enough to melt, and not trip the breaker? I'm pretty sure that is only a 15A breaker in ours, and it is the only thing on that breaker. It seems like it would take a lot of amps to actually melt things inside of there...
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2020 Montana 3741FK
2020 Chevy SRW 3500HD Duramax/Allison High Country
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06-03-2020, 08:50 AM
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#10
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,321
M.O.C. #17894
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all I know is I moved that box very slightly and got a firework show. Breaker never tripped
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06-03-2020, 10:12 AM
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#11
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Montana Master
Join Date: Dec 2009
Location: Sebring
Posts: 3,661
M.O.C. #9969
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I guess we were lucky, when our wires to the relay melted they shorted out and tripped the breaker. Same, only thing left of the wire nuts was the wire spring.
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Michelle & Ann
2018 Chevy 3500HD High Country DRW 4X4 Crew Cab w/Duramax/Allison, Formally 2010 Montana 2955RL, Now Loaded 2016 SOB, Mor/ryde IS, Disc Brakes & Pin Box, Comfort Ride Hitch, Sailun 17.5 Tires.
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06-03-2020, 11:06 AM
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#12
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Montana Master
Join Date: Oct 2006
Location: McKinney
Posts: 7,177
M.O.C. #6433
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Actually it can overheat to the point of melting or fire without exceeding the breaker rating. A loose wire connection causes resistance. And current flowing thru a resistance causes heat. Heat in watts is the current squared times the resistance. That’s the principle of light bulbs, get the element (resistance) so hot they glow.
Wire nut connections, done correctly, work well. But not done correctly can lead to a bad connection over time.
__________________
Bill & Patricia
Riley, our Golden
2007 3075RL (recently sold, currently without)
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06-03-2020, 01:24 PM
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#13
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,321
M.O.C. #17894
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Quote:
Originally Posted by BB_TX
Actually it can overheat to the point of melting or fire without exceeding the breaker rating. A loose wire connection causes resistance. And current flowing thru a resistance causes heat. Heat in watts is the current squared times the resistance. That’s the principle of light bulbs, get the element (resistance) so hot they glow.
Wire nut connections, done correctly, work well. But not done correctly can lead to a bad connection over time.
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I agree a correctly wire nutted connection should be fine. I believe the issue is trying to wire nut together a solid and a stranded wire.
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06-03-2020, 02:07 PM
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#14
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Montana Master
Join Date: Oct 2019
Location: Hesston
Posts: 735
M.O.C. #25060
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Quote:
Originally Posted by beeje
I agree a correctly wire nutted connection should be fine. I believe the issue is trying to wire nut together a solid and a stranded wire.
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Yeah, I never like those connections either. However, that's probably not as much as issue with Keystone as it is with the heater manufacturer for using stranded on the heater side. I'm sure they do that so that it's easier to assemble FOR THEM...
__________________
2020 Montana 3741FK
2020 Chevy SRW 3500HD Duramax/Allison High Country
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06-07-2020, 02:47 PM
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#15
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Montana Fan
Join Date: Mar 2019
Location: Heber City
Posts: 117
M.O.C. #23676
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I am glad you found this in time to prevent a possible fire. I have to be honest. When we are not physically inside our RV, I turn off everything on AC power except the main Air conditioner. We also close the propane tanks. Don’t do this when boondocking on 12v.
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Craig and Mary
2017 Montana 3820FK
2020 GMC 3500HD
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06-07-2020, 07:03 PM
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#16
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Established Member
Join Date: May 2020
Location: Rapid City
Posts: 46
M.O.C. #26357
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Wow, glad you found it. This is a good reason to investigate any hot wire or melting plastic smell. These units bounce, bump, and flex as we travel. A properly tightened and checked wire nut should take it but that is only if it was properly connected and tightened.
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06-08-2020, 05:28 AM
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#17
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Montana Master
Join Date: Jul 2014
Location: Upstate NY
Posts: 1,788
M.O.C. #14547
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Guess I'll add that to my list of "too do's". I believe our HW heater is reasonably accessible after removing a panel in a cabinet.
Wire nuts have their place but I'm beginning to believe that the rolling earthquakes that are our RVs is not the right application. but should be pull apart connectors such as the tow vehicles
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Dave W
2014 Montana High Country 343RL (Sold!)
2011 Ford 6.7 Lariat CCLB (Went to PU Heaven)
2019 F150SC XLT SE Sport,w/full tow package
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06-08-2020, 07:00 AM
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#18
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Seasoned Camper
Join Date: Sep 2018
Location: Conklin
Posts: 79
M.O.C. #22648
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This seems to be a rather common problem. I had the same thing on my 2017 MHC 305RL. We bought it used in 2018. When I turned on the electric water heater element I smelled burning wires. We just didn't use it. Finally got around to looking into it a few weeks ago and traced it to the junction box (plastic) where the supply 120v connected to the water heater. I could see the plastic on the junction box (not really a box - just a covering) melted. I had to twist my body and arms between drain pipes, furnace ducts, etc. to just be able to reach it. Turned out that the 120v wires were connected with wire nuts, and the hot side was the culprit. I stripped back the burned part of the wires and reconnected using crimp on connectors. That fixed it - my water heater now works on 120v. It was probably a poor connection right from the factory, but I agree that I would be very hesitant to use wire nuts in any connection because of all the vibration over time.
__________________
2017 Montana High Country 305RL, MORryde IS and disc brakes, Victron 3000, four Battleborn 100ah, two 30A Victron DC-DC chargers, no solar
2019 Ford F350, SRW, 4x4 Crew Cab, 6.5' box, 6.7 Powerstroke Diesel, TransferFlow 50 gal aux tank, Hensley BD5 hitch
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