(seeking advice) Furnace Wiring Burning up!

[08_Palomono_Cam]

** WE FIXED THIS ISSUE!!! I WISH THERE WERE A WAY TO THANK EVERY SINGLE PERSON WHO HELPED WITH THIS ISSUE!!! Here is the fix. The previous owner built the battery/solar system without a camper chassis ground! this means that when the camper and truck were unplugged from each other, the only return ground for the appliances that use battery was through the only wire that made a direct connection from the camper chassis to the negative of the battery, which is the furnace wire. To fix this, we connected a ground wire from the battery negative to the camper chassis...then for safe sleeping and peace of mind (backup), we connected a thick ground from the furnace negative to the battery negative too. now i have no problems at all .

08 Palomino Pop up Truck Camper.

I am a novice, and enjoy learning, which is why I am hoping to get some help! In USA Ohio. Camper was made in 2008 in michigan.

The ground wire of the LP Propane furnace keeps burning up (when the furnace is off). I've owned the camper for months and this has just started happening recently.

When it burnt up the first time, I replaced the wires and control board, and fired it up. worked great for a few days no problems.... then Last night (while not in use) i caught it in the act again. I smelled burning and went back to see the ground wire RED HOT. ground wire leading from the camper to the furnace. Immediately disconnected the battery. . Insulation burnt off, and melting everything it was touching. The wire only burns between the ground terminal and where it is connected to the camper's wiring at the nut. (see photos)

I have a Suburban NT16-SE Furnace in my truck camper. This camper sits in the bed of my truck with a thick rubber mat underneath it.

It has a solar panel that leads to a regulator and voltage meter that charges a deep cycle battery. The battery then runs to the appliances.

The previous owner removed a refrigerator but i dont think its related to my issue

Here are the attached photos. With descriptions.

https://imgur.com/a/UlyK3



Happy to provide more information!

[westend]

You need someone knowledgeable to straighten out your electrical system. Operating with a gas line used as a ground is dangerous AF.

One easy way to establish a 12V chassis ground is to connect a cable from the battery's (-) post to the chassis frame. This problem has nothing to do with connecting your truck with the umbilical, BTW.

[MEXICOWANDERER]

The terminology can be confusing, but "...chassis ground (which is what is in play here) is a separate issue from earthing. It's somewhat unfortunate that both are commonly called 'ground'"...



This is why I take pains to refer to things as

Chassis negative

Earth ground

[time2roll]

Rvpapa wrote:
So in effect you are useing the PROPANE line as a main battery ground. Now that IS scary.
Art.

Yea that would do it.

[Rvpapa]

QUOTE "The camper battery is NOT grounded to the camper chassis, but the propane tube leading to the furnace is grounded to the camper chassis....So when the trailer cable was removed, everything in the camper was pumping out from the battery, then trying to ground to the propane tube into the camper chassis, which never leads back to the battery, which causes the smallest wire in the system to smoke up."
So in effect you are useing the PROPANE line as a main battery ground. Now that IS scary.
Art.

[time2roll]

That much power has to come from somewhere. Does anything work if that ground is disconnected? Have you checked continuity of the main ground bus to the frame? Have you pulled all the fuses to see if that cuts the power? Most these circuits are fused so that much power should open a fuse. Are the fuses the right size? Is the wire undersized? Are you even sure it is 12v power? If you think the power is from the thermostat... did you disconnect it?

Electricity is all about divide and conquer. You need to start splitting up the system until something changes.

[08_Palomono_Cam]

time2roll wrote:
Have someone else look at it. If you know anyone that knows their way around a voltmeter they might spot something easy. Don't be an island... get some help on this.

my electrician neighbor is helping me out...we're both stumped, but betting that it's either a reversed thermostat wire, or a complex grounding issue which you can find above^

do you know if those Dinosaur Electronic 50 Pin Plus fan have polarity? I am 99% sure i didnt sway those thermostat wires, but my neighbor advised me to ask

[08_Palomono_Cam]

DrewE wrote:
I predict that if you remove the furnace (and its ground wire), nothing electrical will work anymore--or, at least, some things electrical will not work. It shouldn't be that way, but it sure looks like your chassis ground/negative return is all going through that wire. Remove it and you don't have a circuit and your stuff can't run.

You would also need to safely cap off the propane connection to the furnace.

Just got a cap today. Still himming and hawing over trying again....Everything still works with the furnace out...even with the trailer cable unplugged (so only running from camper battery)....which makes me think everything in the camper is grounded through the camper battery (until I plug the trailer cable back into it, and then it grounds through the truck chassis)

The camper battery is NOT grounded to the camper chassis, but the propane tube leading to the furnace is grounded to the camper chassis....So when the trailer cable was removed, everything in the camper was pumping out from the battery, then trying to ground to the propane tube into the camper chassis, which never leads back to the battery, which causes the smallest wire in the system to smoke up.



All this aside, I am curious... Does the thermostat and the board (Dinosaur Electronic 50 Pin Plus fan) of the furnace have polarity? I am 99% sure I didnt mix up the polarity of the thermostat, but maybe that could be my problem too. I'm betting on my grounding issue though.

[DrewE]

I predict that if you remove the furnace (and its ground wire), nothing electrical will work anymore--or, at least, some things electrical will not work. It shouldn't be that way, but it sure looks like your chassis ground/negative return is all going through that wire. Remove it and you don't have a circuit and your stuff can't run.

You would also need to safely cap off the propane connection to the furnace.

[time2roll]

Have someone else look at it. If you know anyone that knows their way around a voltmeter they might spot something easy. Don't be an island... get some help on this.

[08_Palomono_Cam]

FINAL UPDATE:

After digging into the wiring of the battery and the camper, I am just deciding this is going to be a loss. I'm gonna take the furnace out and cap it all up.

The connections are all solid among observation.

I don't have the resources or the time to fix this, and would probably end up breaking something else during the process...:R

my lights, fans, solar charger, etc all works great and I don't want to ruin it. We're only going to camp in the Spring, Summer, and Fall anyway.

Thanks immensely to everyone who helped. I ended up learning a lot about my system.

Jake

[MrWizard]

You need to get into the converter charger 12vdc distribution
You have lost the main negative return path between battery and camper body
Broken lose wire, dirty corroded connection
The battery neg is connecting thru the furnace to camper connection
The power return path for the camper is going thru the furnace wire
Which is not large enough, for the whole camper , and all loads

[08_Palomono_Cam]

DrewE wrote:
I doubt the connection to the truck is your problem; at least, it is not the main problem. You should not have wires becoming incandescent just because you don't have the truck connection in place.

Thanks for your response.

Ok. So Now I have a choice. I do not think I have the knowledge to proceed on my own. Is it a possibility that I can just remove the furnace, cap off the wiring to the furnace, and only go camping in the summer?

would this pose any risks, based on the knowledge of my system

[DrewE]

You don't need an earth ground for the 12V system to work. The terminology can be confusing, but chassis ground (which is what is in play here) is a separate issue from earthing. It's somewhat unfortunate that both are commonly called "ground."

I doubt the connection to the truck is your problem; at least, it is not the main problem. You should not have wires becoming incandescent just because you don't have the truck connection in place.

[CJW8]

Either run a #2 wire from your furnace to frame ground (JK, bad idea) or fix your battery to frame ground.