Water Heater Stopped Working on Electric / Found Burnt Wire

[LeftOverParts]

Hello MOC members. Sharing a problem with the water heater and the fix.

During a trip to Quarzsite in Jan (before the rally) we had a burning plastic smell come from the staircase. Looked in the basement, battery compartment, cord reel, and didn’t find anything. Everything seemed to work and the trip went as planned. Last week we were at Morro Bay and the hot water was on electric heat but the water didn’t get very hot and didn’t last.

Breaker did not trip. Went to see if the reset button could be pushed and the 120 VAC side was solid. Opened the cover and the first picture shows the burned-out connector, wire, and overheated thermostats. You can also see the exposed wire strands where the wire melted where it is adjacent to the metal flange of the heater shell. It appears the beaker didn’t trip because the thermostats got hot from the short and killed the power.

Second picture shows the new thermostats and wiring. Wiring is 14 AWG 600V 105C marine wire and added a fiberglass cover. Ran the wire so it wouldn’t run under the flange. That wire and cover goes to the heating element which tested OK. I checked the other wires at the top and they were dented but not worn so added a layer of electrical tape on the wires where they are adjacent to the upper flange (it’s hard to see in the 2nd picture).

Happy to report it’s working again.

Note: The plastic cover has an inner frame that looks like it would keep the wires from contacting that metal flange so sure how that wire came to short out. I thought about folding the flange over but was concerned that the gasketed surface would become too wavy. Too much work to take the outer frame and that shell off the trailer to pound the flanges flat. I’m going to check the new wire every few trips to see how it’s holding up.

[BB_TX]

Very likely a bad wire connection in the spade connector, possibly crimped on part of the insulation. Something like that can overheat to the point of burning without exceeding the current rating of the circuit breaker. A little resistance in a connection point and a high current creates a lot of localized heat. Heat in watts is the resistance times the current squared. You are certainly not the first that has had that same issue.

The same thing has happened to a number of people in the outside connector where the 50 amp power cord plugs into the trailer.

[Todd & Mary]

We had the exact same connector fail in Jan 2024 on our WH. It also damaged the thermostat. So a quick trip to the local RV Dealer in Quartzsite AZ. which had to order it. So 3 days later it came in and i replaced it as well as crimping on a new terminal and all is well again.

[jkxtreme]

2questions…
Are these water heaters like a residential water heater where only one element is ‘on’ at a time?
What amp draw are you seeing

[BB_TX]

Originally Posted by jkxtreme

2questions…
Are these water heaters like a residential water heater where only one element is ‘on’ at a time?
What amp draw are you seeing

Unlike a large home water heater, RV water heaters have only a single 120 vac heating element, typically 1440 watts (so 12 amps rated).

[jkxtreme]

Thanks a bunch. If I had looked at the pictures a little closer I guess I would have realized that.

[TomCat]

Had a similar issue with my 2017 High Country. Found the burnt connection actually at the water heater. I had to lay in a contorted position, and am thankful for being tall with long arms! I was able to fix it without removing the water heater. Seems to be a common problem.