48 hours on genny. Electrical shorted now.

[06bowtie_guy]

Dealer installed the onan 5500 into my trailer. This weekend it was running fine. Turned it off without any issue, had been running coffee machine.

Later in the evening went to fire it back up. Powers up fine, no codes listed on the hour meter screen. Will not power up the trailer. I checked all breakers and nothing was tripped.

I followed some wiring to a junction box, have an ohm meter with me so was going to check if it was putting out power. Here is what I found.

20140921_102321 by funinmud, on Flickr

Unsure if you can tell but the white wires were in a marret with electrical tape on them. The plastic of the marret is now melted off. Not pictured is the cover that was removed, had some marks on it.

Unpacked the trailer once home and dropped it off at the dealer (they are closed today)

Curious if anyone may have an idea of damage caused, could the generator side of the unit have gotten fried because of that? They did the install so that's why it's back there now.

Thx for input!

[JLTN_James]

I had the OEM hot conductor from my shore power cord come loose in the distribution panel where it terminated into a pigtailed lug connection to the distribution bus (no main breaker inside the trailer). It overheated to the point where it melted some of the stranded pigtail conductor. I only had two loads on, the converter and a 1500W electric heater. Total load was less than 15A on a 30A service. Not nearly enough to cause a breaker to trip. I wish I had taken photos of the situation but I was concerned about getting it repaired while I still had daylight.
As part of my repair, I removed the lug connection and pigtail, installed a 30A main breaker, and terminated the shore conductor directly to that.

[wa8yxm]

Well if you got to short to ground the white wire is the one to short.

But that said.. Wire nuts joining stranded to solid wire is not always the best chocie, I have had two such connections fail on me (The repair involved my big solder gun, some solder, and .. Let's just say it works better) evidence is overheating of that fitting, which may be caused by a bad connection.

Re-do that connection

Check breakers on generator as well.

[06bowtie_guy]

That box is mounted on the stuff often used under the trailer, the material is also used in the front compartment of this trailer.

Genny is a 50 amp unit with a 30 amp breaker and a 20. I'm thinking there is 2 wires going to each feed into the trailer but not positive on that as I didn't follow wires to fix it.

I'm going to add that box to my list of things to check for the next little while, make sure nothing is coming loose.

[ken_white]

NinerBikes wrote:
... Good wirenut jobs should never require electrical tape.

Too much vibration and jarring to think a simple mechanical connection, like a wire nut, will stay tight and not vibrate loose without something holding it in place.

Tape is cheap and easy to apply, so I add it too...

[westend]

NinerBikes wrote:

westend wrote:
Neutral's were not connected fully inside the wire nut. That led to the arcing and the heat. If the neutral becomes disconnected, you will have no power continuous to the RV's load center. Probably no damage to the gen set because no power is flowing through the bad connection.

This /\. Anyone that's done electrical on residential housing has seen this a time or two in a junction box or in a main circuit breaker. Poor workmanship, not enough stripped wire on both neutrals, and both of them not completely twisted together tight enough before the wire nut goes on.

Good wirenut jobs should never require electrical tape.

Guilty, as well. FWIW, I've quit trying to jam five or six neutrals in one nut, choosing to pigtail two or three and then combining.

Tape..., I sometimes use it, depends on the circumstances. If trying to install more than the usual three into a single gang box and a switch or receptacle, or having cheap wire nuts, I'll sometimes tape them. If Chris Bryant says he uses tape in RV's, that's good enough for me. It's not that much more work and I can see the vibration angle causing a problem.

[NinerBikes]

westend wrote:
Neutral's were not connected fully inside the wire nut. That led to the arcing and the heat. If the neutral becomes disconnected, you will have no power continuous to the RV's load center. Probably no damage to the gen set because no power is flowing through the bad connection.

This /\. Anyone that's done electrical on residential housing has seen this a time or two in a junction box or in a main circuit breaker. Poor workmanship, not enough stripped wire on both neutrals, and both of them not completely twisted together tight enough before the wire nut goes on.

Good wirenut jobs should never require electrical tape.

[TEXAS]

westend It does appear that way. Also a bad spot to have wires. One good road hazard could take out the complete system.

[westend]

Reread this thread and noticed something else: The material that junction box is mounted on appears to be the same woven plastic that is attached to the under-belly area on some TT's. If that box is located on a trailer's under-belly, I would use a weatherproof box and not a standard 4' box that has holes.

[TEXAS]

Did they they also fix their screw up on the top connector. Wires in a metal fitting. Sharp edge and no protection for the wires. Fire source in the making.

[Chris_Bryant]

A couple of points- electrical tape is called for in this case because of vibration- I always tape wire nuts in RVs. The wire sizes are #10 out of the genset (30 amps) to #6 in the rig (50 amps). The OEM has to wire it for the maximum load, because the genset may not be installed from the factory.

[Dusty_R]

mrgreetis wrote:
I learned something new - what a "marrette" is.
Tried finding a definition, that led me to this link
clicky

Never knew that...

Glad you checked it out I did not know either and I'm a retired construction electrician. We always called them "wire nuts". There are a lot of different makes of them.
It's a good practice to tug on each wire, after installing a wire nut to be sure all the wires are caught/holding in the wire nut.

I was working on a job once making joints/connecting on #12 stranded wire. I had made all the joints in a box and was pushing the wires into the box so I could put the cover on, and a wire came out of a wire nut. I thought that I must of not check that one. I fixed that one then went on to the next box, made all the joints in that box, and made sure that I pulled each one in that box, they were good. But when I pushed the wires into the box another joint fell apart. I found out that the wire nuts that I was using were the poorest ones that I had ever used and they were NOT holding the wires like they should.


Dusty

[SCVJeff]

MrWizard wrote:
French word for "Wire Nut"

Maybe it's a PC thing because the real crazies didn't want to be referred to as Wire Nuts.. 🙂

[time2roll]

I am still a little queezy about the size difference between the red/black pair that looks like #6 vs the white/black w/yellow stripe looks like #12.

What size breaker/generator feeds this box? What size is that small wire?

The new bus connection should prove more reliable with the size differential.

[MrWizard]

French word for "Wire Nut"