Electrical problem. Probably expensive.

[Adam Hicklin]

I need the collective BAC brain trust.  Coach is stored at my home plugged in to a dedicated 50A service.  Went inside yesterday and noticed everything was dead, lights were dim/not working, no incoming AC power, nothing registering on the inverter panel.  Went outside to verify pedestal breaker hadn’t tripped.  All seemed normal.  Power was still on. Turned everything off.  Started investigating today.  Verified pedestal power was good. Got in the bay and discovered that the neutral on the LOAD side of the surge guard is fried (see picture). Transfer switch looked fine.  Mine is wired: incoming AC/generator to transfer switch. Transfer switch to Surge Guard.  Surge guard to breaker panel.  Everything in breaker panel looked fine.  No burned wire.  Everything tight.  All connections at transfer switch and Surge Guard were tight.  I was in the coach about a week ago and everything was fine.  It’s stored.  There has been no significant load on the system. 

Questions: 1. I have a little l electrical experience and know dropping the neutral on a 240/120 system is no bueno.  I’m sure there is electrical component damage to electronics and what not.  Good thing is it was stored so nothing was on.  But why would the neutral over heat where it did, coming out of the surge protector.  Could there be something wrong in the surge protector?  2. Where do I go from here?  I’m not sure how far the burned wire goes up the conduit. 

[Adam Hicklin]

Just realized when I viewed the pictures... when I first got to the transfer switch and SurgeGuard, power was on and feeding through to the load side of the SurgeGuard.  That’s when I turned it off at the pedestal. 

[Fred Brooks]

    Adam,
  Picture #2 shows the origin of the short working its way into the surge protector. Note the heat deformity next to the red wire. Somewhere inside the surge protector on the load side, the red wire and the neutral got together. Seems strange under a no load condition and the green LED's all lit.
   Typically when a neutral is lost under a load, either it quits working or creates a path back to ground by way of the least resistance like a PC Board. Your insurance should cover this failure.
  To check for damage downstream of the failure, replace the damaged neutral wire (add a j-box if necessary), turn off all 120 circuit breakers. Turn on the 50amp main first, then 1 at a time and see what works. Hope this helps, Fred
PM me if you want to talk on the phone.

[Adam Hicklin]

Thanks Fred.  Tomorrow I’ll peel back conduit covering the wire where the neutral is burned. See how far it goes.  I added this Surge Guard about 4 years ago.  No,issues.  Wouldn’t it be ironic if the Surge guard caused the problem!  I sent an email to Surge Guard. I’ll see what they come back with.  I pulled out a couple plugs inside that had a plug in them just to see if there was any indication of excessive heat. Everything looked good. Everything around the inverter looked good.  Charger would have been the only possible load at the time, and at most that would have been float charging. 

[Fred Brooks]

   Adam,
I agree that there was no load and I have never seen a surge guard fail like that in 15 years. They make a quality product and as a matter of fact I have the same unit on my coach. Let me know what they say, perhaps they may want it back to analyze the internal failure. Fred

[Eric Maclean]

Fred
I hate to disagree with you but the burnt neutral wire is on the load side of the unit which would lead me to believe that the burn was caused by either a loose connection at the surge protector in which case the burn should be limited to the wire with in inches of the loose connection.
If there were a short at the unit itself the neutral wire shouldn't have been involved.
If there where a short farther down stream say at the breaker panel or wiring between the surge protector and the breaker panel the hot leg which was shorted should show signs of over current as well ( insulation deformation).
At this point I'd cut the conduit open to investigate how far back the neutral is burnt if it is limited to the area close to the surge protector I'd look very closely at the neutral connection at the surge protector for discoloration and burning of the connector screw.
If the burn runs back farther follow it to the origin of the short.
Remember in our coaches there are usually are no 240 volt loads there fore all the loads weather supplied from L1 or L2 all return via that one neutral .
I would guess that the connection at the surge protector has been compromised for quite some time and that the burn happened before the coach was put in storage and as usualy happens the copper wire which has been overheated oxidizes and the connections is lost.
At any rate I would replace the surge protector and burnt neutral wire as it's been my experience that once a connection has been overheated it is impossible to get it tightened well enough to trust again.
Maybe Ed Bunker could chime in here.

Hope this helps
Eric

[Adam Hicklin]

Thanks Eric.  I replaced the inverter in the spring.  At that point I checked all the connections at the transfer switch and surge guard.  Everything was snug, although I didn’t torque them.  So I know at that point all was well.  Yesterday I checked the connections and all were snug.  We had a summer of trips and all seemed fine.  It seems that a short on the load side should have tripped the main breaker, or at least the branch where the short occurred.  I’ll cut back the conduit today and see how far the burn goes. 

[Adam Hicklin]

Update-  was able to peel back the wire insulation.  The neutral was damaged about 6 inches back. I’ll cut out the damage, get a new SurgeGuard.  SurgeGuard said they thought it was a loose neutral just by my description.  I sent them some pictures.  I just find it hard to believe a loose neutral was the case but I guess short of the SurgeGuard being damaged internally, that makes the most sense.  I checked all those connections in the spring.  You can never be too sure, I guess.  I’ll get it hooked back up with new parts then see what the damage is to any electronics. 🤨

[Fred Brooks]

   Guys,
   My statements were based on the fact that I thought all the connections were torqued to spec. I should have asked that question because the entire load returns on the neutral. If the neutral was loose it would have caused the failure and the 6" burned insulation. GOOD call Eric and hopefully all turns out good! Merry Christmas! Fred

[Adam Hicklin]

Another update.  I think I found the problem.  Notice in the picture there are two sets of screws on the connection block.  One set secures wires coming out of the Surge Guard.  The second set secures wires from the coach.  In this case the neutral on the SurgeGuard side was loose.  I never thought of checking that connection as it is done at the factory.  I falsely assumed it was maintenance free.  Lesson learned.  Check those connection periodically.  All of them.

[Neal E Weinmann]

Are you certain the 34560 Surge Guard was a factory installed item? My “standard” factory installed large black TRC 40250 transfer switch has a built in Surge Guard. Perhaps a previous owner added the smaller unit as a sacrificial surge protector and did not properly torque the connections? Just wondering.

[Fred Brooks]

    I went back thru the brochures and the 2004 Marquis showed an "optional" surge guard available. I believe Monaco started installing them shortly there after in the Beaver product line. Fred

[Neal E Weinmann]

FWIW - if there’s a Date of Manufacture on the unit, that may help determine if it was an optional factory install or an added unit.

[Adam Hicklin]

Sorry. I didn’t mean to imply that the SurgeGuard was factory installed on the coach. Only that there is a set of screws securing wires on the SurgeGuard that are factory set.  Notice in this picture, of the units side by side, that they have sealed the connections on the inner block (current model on the right) My guess is I’m not the first to have this loose connection problem. Also notice the burnt wires coming out of the device on the left top. 

[Mike Shumack]

Why is the ground wire on the Load side (top left) so much smaller than the same wire on the Line side?