burned wires in converter. Fix wires or replace converter?

[Caryite]

Hi,

The converter in my TT is not working and I've used a multimeter to confirm that my shore power is providing 120 VAC. It is a 30 amp system.

It appears the burned and corroded wires are the problem from this picture below:



Is it worth cutting off the burned/corroded portion of the wires and then reattaching them to the neutral terminal bar, or does it appear the neutral terminal bar needs to be replaced as well? I was going to try to address the wires first inside of the WF-8944PEC converter (3 years old) before attempting to replace the entire converter.

Any suggestions would be appreciated. I don't plan to work on this until next weekend.

[MEXICOWANDERER]

Replacing is no fun
Fixing and learning is rewarding in more ways than two.
Happy trails!

[Caryite]

Thanks to all who have chimed in on this thread for the help to get this addressed. I was able to use some recommended DeOxit coating on the newly restripped wires and hook up the wires to the new bus last night with positive results. I have tightened all connections to the hot, neutral, and ground bus connections as well.



Special thanks to the kind folks at WFCO (converter mfgr) who provided me an extra phenolic board to exactly match the old phenolic material that had burned.

I plan to recharge my 12V battery over the weekend and monitor all connnections and behavior. I learned a lot in working on this with everyone's help.

Thank you again!

[Caryite]

I purchased a replacement neutral buss (Square D PK7GTA), open to comments if this is going to be enough or not.

http://datasheet.octopart.com/PK7GTA-Square-D-datasheet-21215744.pdf

The datasheet doesn't indicate if it is unplated aluminum or not, so perhaps I'll just assume the worst that it is.

For the record, the original buss was part of the initial install of the Distribution Center, so obviously I am trying to replace this with something that is going to last.

If this means I need to get DeOxit D100 and DeOxit Shield to apply to the buss and the copper wires, then so be it. Not sure where it was implied that sound advice was going to be ignored in this thread either, but perhaps that is the medicine to take as part of getting some good suggestions.

Here's a photo of the replacement buss and the restripped wires (1 hot/black from the main needed restripping as well).



If I need to get a better buss than the one I found locally, then I'll pursue that too. I don't have a problem changing gears as nothing has been hooked up yet. I'm still working on securing a phenolic sheet.

Did I mention yet that I'm not in a hurry and would rather get this right? All screws have been retightened as well from all the other unaffected connections. Thanks again to all for the helpful suggestions.

[mchero]

Good post Mex!!

[MEXICOWANDERER]

DO NOT NOT NOT NOT NOT
clamp bare copper to bare aluminum!

Clear enough?

Unplated aluminum is a time bomb waiting for its last tic...

Those parts are manufactured then within minutes get plated with electrolytic tin. It's not an inexpensive process so it is done for a specific reason. NEMA would instantly reject a current-carrying device of aluminum unplated. Aluminum oxide is the culprit and aluminum oxide forms very quickly on unplated aluminum. Cosmoline (NoOx) coats aluminum and barriers air away.

Rude and crude my tests SUGGEST DeOxit D100 removes unnoticeable aluminum oxide from bare aluminum and further tinkering SUGGESTS DeOxit Shield blocks oxide formation for an unknown length of time. With the hotel I had Siemens box conductors gold plated (don't ask the cost) fifteen years ago. Tinned wires and a mean ass tropical salt air environment.

I can envision a vast majority of these type problems happening because domestic parts are being used in conditions with vibration, aluminum, steel and copper are being forced to expand and contract together and fine strand copper wire does not gain the same elastic pre tension force of building wire. Every last breaker box on the road should be opened up and ALL SCREWS RETIGHTENED. This statement ends with a period. The frequency of this is near stupid. I did it twice on new construction vessels and once on AC RV repair work. Every last initially properly torqued connection was found to be wanting.

After you read this and ignore the advice please save server space and do not wail when it happens ro you. Checking screw torque is fast and easy after shore power and inverter disconnection. Fires burn RVs to the ground including sometimes its occupants. Not funny at all. Get enough PVC fumes in the air and death by asphyxiation is a certainty. Also not funny.

[mchero]

Bad connection on the neutral buss....that simple. Those connections will work loose & the resulting bad connection gets hot!

The first response to the OP,"Wouldn't it better to replace what caused the wires to burn?" was somewhat odd. Must not have understood what was going on.

I would suggest you tighten up ALL connections on that neutral buss bar, strip back the burnt wires & reconnect. "if" the buss bar gets hot again you will see the discoloration.

It's a good idea, like the previous poster suggested to inspect entire 110VAC wires. Also pop the covers on the 120VAC fuse panel & Xfer switch & look for loose connections. Pull att the lower drawers and inspect/clean.

On my prior 93 PaceI found a loose common wire in the 50Amp Xfer switch. Cleaned up connection & tightened & all was back to normal.
During another inspection just last week I found a 12VDC 4 lug grounding bar. ALL THREE ground lugs where finger tight! The Furnace, Pump switch & Vanity lights where connected to that buss bar! Just last year the OEM ignitor board in that furnace failed, might have been a result of a loose ground wire!

[Coolerman]

That looks to be a piece of phenolic (ie a piece of circuit board with no components on it) used to insulate the neutral buss from the chassis ground. It if is not burnt all the way through then there is no need to replace it. It it is burnt to the point of being fragile, then I would replace it. You can get this stuff easily be searching phenolic on Google. Very cheap stuff.

[Caryite]

Here's an update after IDing each of the wires along the neutral buss bar and a better picture of the bar itself.



I numbered each hole 1-7 from left to right. Here's what is connected to each:

hole 1 - converter
hole 2 - empty
hole 3 - AC
hole 4a - water heater
hole 4b - microwave
hole 5a - GFI
hole 5b - refrig
hole 6 - main (black goes into 30 amp fuse)
hole 7 - empty

All of the responses prior were focused on hole 6 or 5a/b being the problem. I think the above shot shows hole 6 on the main from shore power being the issue. Comments are welcome.

I am replacing the buss and there is plenty of wire length behind the converter to use after I've cut the burned neutral wires.

The concern is this area behind the buss that looks pretty burned as well.



Should I try to replace this as well, or just get a new enclosure for the WF-8955 distribution center?

[RJsfishin]

If you splice a wire, twist it, then solder it, then wire nut it. It will never give a problem.

[mabynack]

As a former mechanic, I can tell you that splicing wires is not really desirable. The splices can work loose and cause major headaches when you're trying to diagnose future wiring issues. I have worked on many vehicles where the owner had wired accessories by splicing into existing circuits. It can be a nightmare.

As previous posters have suggested, first find out if you have a voltage issue or a moisture issue causing corrosion or shorting. I would recommend replacing the converter instead of rewiring it. They're not that expensive when you compare the cost of fire damage or burned up wiring caused by a bad wiring job.

[wa8yxm]

I would cut back the burned wires, Re-dress, Clean up and TIGHTEN THOSE SCREWS that clamp them very tight.. or to be more precise: I Did as I just typed.

Also tighten all the other wire clamp screws while you are there.

[Caryite]

Thanks all for the very helpful observations. Will be replacing with a new buss, strip the wire, and watch like a hawk from here on out.

Will be checking and retightening every year as was suggested as well.

[CJW8]

In the industry I am in, we do annual infrared surveys of all of our switchgear (breakers and contactors) These range in size from 15 amps to 1000's of amps. We use very sophisticated cameras and always find problems that were not there the year before.

You can periodically do the same thing with your infrared gun you use to check your wheel bearings and tires. Make sure the circuit you are testing is under load and shoot the breaker and corresponding neutral connection to the buss. Record your finding on a napkin but preferably on an excel spreadsheet. You'll spot trouble long before it looks like the attached photo. These problems usually do not happen over night but get worse and worse as time goes on. Add to this an RV going over a California concrete freeway and things tend to come loose.

[westend]

DrewE wrote:

westend wrote:
I'll go against the "right hand wires" theory in this. It appears the neutral bus was connected to the load center correctly with the three mounting screws. It appears that every wire has lost jacket material from heat, the right side being the worst. I would guess that the cause is a loose connection within the load center to the shore cord or a failing shore cord that allowed connection but a lot of resistance.

I'd suggest to check resistance of the whole neutral path from the male neutral plug end to the neutral bus.

One of the wires connecting to the neutral bus is the wire from the shore power cord (possibly via a transfer switch). From the picture, it looks like it's the rightmost connection, as that's a 10 gauge wire, verifiable by the orange outer jacket of the romex where it enters the electric box (as well as by its comparatively larger diameter). The hot from this wire goes to the uppermost breaker, which conventionally would be where you'd put the main breaker, and which further tends to confirm that this is the input wire.

The heat is not coming up the wire from some poor connection further down, as the hottest parts were clearly near the bus bar. If it were from a poor connection further down, the wire would be more burned further down.

To my eye, the second position in on the right with the doubled-up wires appears to be the culprit, but that's rather a moot concern at this point. It needs to be redone for safety regardless.

After reading your post and looking again, I humbly remove my first diagnosis. The heat is certainly centered towards just a few lugs. Your diagnosis would be the most plausible.

Thankfully, it appears the OP has enough usable wire to install the new bus, strip wire, and start over. I've bought bus bars at the big box stores but an electrical distributor will have better ones. It is probably an orderable replacement part from the MFG, too.