A Word Of Caution !!

[lewster]

Just a quick note about a repair that I just finished on an SOB 5th wheel. I won't mention the brand, but it started like this:

I received a service call from a fellow that had just pulled into a local FL State Park and had no 12VDC and noticed a burning smell. By the time I got there, he had removed the +12VDC cable from his battery and I began to investigate.

16 hours later over the next 3 days, I would up re-wiring ALL of his battery leads to the converter, added a new battery cut-off switch to replace the one in the trailer that was fused closed, his 7 way leads from the front to the back of the trailer and his 12VDC feed to the lights on his slide-out. It seems that this battery cable fed to the converter, and had no clamps or other strain relief on it. The jostling from travel caused it to rub against the frame, creating a direct short to ground. The situation was compounded by the failure of a 50 amp DC circuit breaker to detect the short and dis-engage the circuit. It seems that the very high current draw (600 amps from the battery) fused the breaker in the closed position!!

This generated so much heat in the 4 ga. cable, that it melted the insulation from 20' of cable, fused itself to a bunch of other wires causing them to short to ground as well, and even melted itself half way thru the ABS coupling to the black water tank valve!!!

The point of all this is: when you re-wire your trailers and MoHos, be sure to clamp and cable ALL of your wires so that they DO NOT MOVE. Use wire loom where ever possible. Failure to do this could result in a situation similar to the above description.

He was VERY LUCKY that he removed the battery lead when he did. I figured that he was only a few minutes from a fire!!!

BE CAREFUL OUT THERE

[john hd]

lew

although i cannot say much for the skill involved in the wiring rats nest airstream left under my kitchen cabinets, the shell areas and pass throughs in the ribs are all well constructed with grommets and loop tie downs.

many of the older trailers i have seen taken apart show this care too.

at least airstream seems to get it right where it counts.

john

[Wharf Rats]

Hi Lew. Very good post, we see that a lot on some of the newer boats, I won't mention any brands either. People tend to forget the batteries are the heart of the unit, and the power of DC even 12 volt is nothing to take lightly. Great heads up Thanks, ---Mark---

[5cats]

Hi Lew, thanks for the story. Concidentally, I've been worried about the factory wiring in my own 2007 AS: It's hard to believe they let these things go out the door like this! I did what I could to reorganize that mess:
BEFORE:

AFTER:
Hopefully I lashed it all down well

My motivation was to add a battery monitor and prep for a solar PV install. I could wish for a better layout, but I left the components as-mounted to avoid adding more holes in the inner skin...

Cheers,
-jd.

[kincaidjesse]

Hi, Lew:

Do you think my problem has a connection to yours?

Everytime I haul my '66 Ambassador for extended miles, I start burning out dash fuses and fuel pump relays. My mechanic thinks I am crazy but after two new fuel pump replacements that I didn't need, I finally figured out that there must be some kind of short back-feed from the trailer brake/tail light hook-up and the PU fuse problem.

Without fail, truck dash and tail light fuses, along with radio and AC fuses burn out at the same time, with the fuel pump relay shortly to follow. I now carry an extra fuel pump relay and 5 boxes of different sized fuses. I change them and all is OK.

Do you know what could be causing this connected with the trailer brake/tail light hook-up? Help is appreciated. It only happens when I am out of state, of course.

[AYRSTRM2]

Originally Posted by 5cats

Hi Lew, thanks for the story. Concidentally, I've been worried about the factory wiring in my own 2007 AS: It's hard to believe they let these things go out the door like this! I did what I could to reorganize that mess:

Hopefully I lashed it all down well

My motivation was to add a battery monitor and prep for a solar PV install. I could wish for a better layout, but I left the components as-mounted to avoid adding more holes in the inner skin...

Cheers,
-jd.

If that blue wire is high current, it could cause a field that will setup resistance that will cause the wiring to melt, being looped like it is. Unlikely, but can happen if the current is high enough.

[5cats]

Originally Posted by AYRSTRM2

If that blue wire is high current, it could cause a field that will setup resistance that will cause the wiring to melt, being looped like it is. Unlikely, but can happen if the current is high enough.

Good eye! Yeah, that's the solar prewire CAT-5 in blue, coiled with the green & yellow #10s. They are not connected. It's just separated out in prep for installing a solar PV system, coming soon to an airstream near me

Cheers,
-jd.

[flyfisher]

Originally Posted by lewster

The point of all this is: when you re-wire your trailers and MoHos, be sure to clamp and cable ALL of your wires so that they DO NOT MOVE. Use wire loom where ever possible. Failure to do this could result in a situation similar to the above description.

BE CAREFUL OUT THERE

Good point, Lew.

And someone should also tell this to the guys at the Airstream factory when they're making new units!

My trailer almost burned up last year from loose wires going into my generator transfer switch. In looking at all the sloppy wiring done in my trailer, it appears Airstream couldn't have cared less once my trailer was sold and out of their sight.

John

[Silvertwinkie]

Originally Posted by 5cats

It's hard to believe they let these things go out the door like this! -jd.

You'd be shocked what some of us have found lurking in places not typically visted by the average Airstreamer......

[5cats]

Ok, so now I'm curious to see pictures of proper wiring in the airstreams. Anybody?

[lewster]

Originally Posted by kincaidjesse

Hi, Lew:

Do you think my problem has a connection to yours?

Everytime I haul my '66 Ambassador for extended miles, I start burning out dash fuses and fuel pump relays. My mechanic thinks I am crazy but after two new fuel pump replacements that I didn't need, I finally figured out that there must be some kind of short back-feed from the trailer brake/tail light hook-up and the PU fuse problem.

Without fail, truck dash and tail light fuses, along with radio and AC fuses burn out at the same time, with the fuel pump relay shortly to follow. I now carry an extra fuel pump relay and 5 boxes of different sized fuses. I change them and all is OK.

Do you know what could be causing this connected with the trailer brake/tail light hook-up? Help is appreciated. It only happens when I am out of state, of course.

Jesse,

It's really hard to say unless I was there, but you can try a few continuity tests to see if any of your wires are shorting to ground. OTOH, if you have a bare wire somewhere and it is only shorting while you are bouncing down the road, then it will be VERY difficult to find without re-wiring the entire TV and trailer.

I would try the ground continuity tests first, wire by wire, and see what you get. If one of the wires has continuity to ground when it shouldn't, then you can trace down that wire and you should find the culprit.

Does this only happen when you are towing the trailer? If so, and you have no problems with the TV by itself, it would be safe to assume that the problem lies in the trailer wiring, not in the TV. But I did find a similar problem with a 5th wheel rig, and it seemed that the short was in the wiring from the TV's harness to the 7-way plug in the TV. All of the wiring in the trailer checked out, both in continuity and by energizing each individual circuit with a 12VDC battery.

I know that this is sort of general in nature, but I hope it helps!

[r&kweber]

Lew, Would a fuse on the negative side of the system have prevented the major damage? Burned wires... smelly.

[lewster]

Sure, but it would have to be a BIG one, like the ones used for inverter connections. They are usually in the 250-400 amp range, but the sizing would depend on the battery capacity.

His circuit WAS protected by a 50amp DC breaker, but the contacts fused closed. Could have been a bad part from some 3rd world country also. I would suspect that if the positive was properly fused or protected with a 'good' breaker, than it would have tripped or burnt out and there never would have been a problem.

In looking back at it though, his wiring is now done properly and he will not have this type of problem again. I know that the Airstreams are not wired like this sob, but one might consider an over current protective device on the 12 VDC battery feed anyway. It's on my to do list before my summer trip!

[tsunami]

Lew, have been reading this thread with interest. My quetions pertains to the 110v 30A shore power connection. There are adapters available to enable the conversion from 30A to 15/20 Amp. I have used one, but it didn't seem to do anything. Over a short time my light dimmed while connected this way. I was hoping to be able to keep the batteries charged between trips. What's your take on this? Thanks for your endulgence.

[lewster]

Originally Posted by tsunami

Lew, have been reading this thread with interest. My quetions pertains to the 110v 30A shore power connection. There are adapters available to enable the conversion from 30A to 15/20 Amp. I have used one, but it didn't seem to do anything. Over a short time my light dimmed while connected this way. I was hoping to be able to keep the batteries charged between trips. What's your take on this? Thanks for your endulgence.

A 15/20 amp line that feeds your trailer by using a 30-to-15/20 conversion plug should allow you to keep you batteries charged, but probably not much else. It really depends on the converter that you have and how much AC it draws while making DC for the charger section.

A few summers ago while I was full-timing in a Monaco 40' Dynasty, I spent the entire summer hooked to a 20 amp line with 2 conversion plugs that went 50-30 amps and then 30-20 amps. I could run an air conditioner, and not much else, but it got me thru. And the price was right too.......FREE!!

Do you happen to have an 'amp clamp' ? It is a clamp type meter that will read the amp draw from a hot lead without breaking the wire. Sears sells them for about $50, and they read AC and DC amps. Very handy little device.

If you have/get one, you can clamp it over the hot lead going into your trailer and 'read' how much you are drawing. This would be a big help in diagnosing the situation.