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Electrical Arcing / Snapping

Last September I was in a park with 50 amp service.  In the middle of the night I woke up to a loud arcing sound and a bang.  It sounded like a shotgun going off.  I checked everything that I could find.  No evidence of burnt wiring (no burnt wiring smell).  Went back to sleep with 1 eye open.  A couple of hours later the same thing happened.  The arcing lasted maybe 3-5 seconds and another loud bang.  Noise sounded like it was coming from the center of the coach.  I noticed that the voltmeter read 125 volts.  Afraid to drive it I spent 1/2 day checking every possible 110v connection starting at the power pole.  Put a screwdriver on every connection that I could access and could not find anything loose.  Everything works, no breakers tripped, no burnt wiring smell.


No further problems until last weekend.  The same thing happened twice in 1 night.  The voltmeter read 127 volts.  Again no evidence of burnt wiring, everything works and no breakers tripped.


The only thing that I can think of that I didn't check was internal connections on the power cord reel.


Any ideas?


Don & Sue
2009 NImbus 38
2020 Jeep Grand Cherokee toad

Re: Electrical Arcing / Snapping

Reply #1 –
Quote from: djpauls –
Any ideas?
No, sorry, but I would not sleep very well (if at all) until I figured out where the noise was coming from.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Electrical Arcing / Snapping

Reply #2 –
Don,

On your coach (09 Nimbus) don't you have a built in surge protector  that is mounted on the back wall of the bay that houses all your electrical and HWH stuff? (Left side either 2nd or 3rd bay)  If so it could be seeing a voltage spike and doing it's job.  There is another member that has a Nimbus that either his serge protector or transfer switch started acting up similar to your problem. His was when he used his coffee maker though and not during the night.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Electrical Arcing / Snapping

Reply #3 –
Quote from: Pamela & Mike –
Don,

On your coach (09 Nimbus) don't you have a built in surge protector  that is mounted on the back wall of the bay that houses all your electrical and HWH stuff? (Left side either 2nd or 3rd bay)  If so it could be seeing a voltage spike and doing it's job.  There is another member that has a Nimbus that either his serge protector or transfer switch started acting up similar to your problem. His was when he used his coffee maker though and not during the night.

Mike

Hi Mike,
I do in fact have the built in surge protector and I thought the same thing.  According to the owner's manual it is triggered at 135 volts.
Don
Don & Sue
2009 NImbus 38
2020 Jeep Grand Cherokee toad

Re: Electrical Arcing / Snapping

Reply #4 –
Unless it failing?
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Electrical Arcing / Snapping

Reply #5 –
Don,

On some of those surge protectors (that were used during that time frame) there was an adjusting pot for each leg that could be user adjusted. If you have one of those units, one of the adjusting pots may be failing. I wouldn't think that they could be moved by vibration. Just throwing out some possibilities as this is a little strange. 

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Electrical Arcing / Snapping

Reply #6 –
Quote from: djpauls –
Last September I was in a park In the middle of the night I woke up to a loud arcing sound and a bang.  It sounded like a shotgun going off.  A couple of hours later the same thing happened.  The arcing lasted maybe 3-5 seconds and another loud bang. 


No further problems until last weekend.  The same thing happened twice in 1 night.  The voltmeter read 127 volts.  Again no evidence of burnt wiring, everything works and no breakers tripped.


The only thing that I can think of that I didn't check was internal connections on the power cord reel.


Any ideas?

It's going to be in one of the big connections although I can't imagine much of an arc at 120VAC.  Go right down the string and check them all by disassembly and inspection.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Electrical Arcing / Snapping

Reply #7 –
Transfer switch operating?
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Electrical Arcing / Snapping

Reply #8 –
This is a HUGE safety issue.  Arcing and a loud bang indicates a major electrical problem and is dangerous!  Take the coach to a qualified service facility and have this found and repaired asap for your own safety.
Current coach 1996 U320 40'
Previous coach, 1990 36' U280

Re: Electrical Arcing / Snapping

Reply #9 –
My 2003 has a voltage sensor that trips the main ATS if the voltage is too low or too high. Could you be hearing the ATS kicking out and in on a transient voltage spike?

I had mine re-adjusted at FOT last year.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Electrical Arcing / Snapping

Reply #10 –
Quote from: Kemahjohn –
This is a HUGE safety issue.  Arcing and a loud bang indicates a major electrical problem and is dangerous!  Take the coach to a qualified service facility and have this found and repaired asap for your own safety.

I couldn't agree more.  The problem is that likely it is not going to act up.  I am not sure what a "qualified service facility" could do that I haven't already done.  While I am no electrical expert, in my previous life as an RV Dealer for 20 years with a highly respected service department, those qualified technicians used to work for me.  We never had a motorhome come into our shop presenting the symptoms that I have experienced. I have examined every single 110v connection even going as far as to take the cover off of the transfer switch for inspection (the transfer switch seems to be operating properly).

I have not explored the possibility that the surge protector is failing.  I will reach out to TRC for their thoughts.  Interestingly, I just went out to the coach to verify and retrieve the operators manual for the TRC Surge Guard system and noticed no 110v power in the coach.  I plugged it in yesterday to 30 amp and heard the transfer switch activate.  No breakers tripped in coach or in the storage barn.  Turned power source breakers off and then on and now 110v power.  Also noticed that I had left AC1 and 2 on for the furnace.

It's a Hobby!

Don
Don & Sue
2009 NImbus 38
2020 Jeep Grand Cherokee toad

Re: Electrical Arcing / Snapping

Reply #11 –
Quote from: djpauls –
  No breakers tripped in coach or in the storage barn.  Turned power source breakers off and then on and now 110v power.  Also noticed that I had left AC1 and 2 on for the furnace.

It's a Hobby!

Don

Intermmitents are a pain the the ass to find.  You're insurance is paid up, right?
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Electrical Arcing / Snapping

Reply #12 –
Quote from: djpauls –
Last September I was in a park with 50 amp service.  In the middle of the night I woke up to a loud arcing sound and a bang.  It sounded like a shotgun going off.

Got to say, that shotgun sound + arc is typically a transformer blowing, any chance the sound came from outside?  Both the sound and the arc carry for a good distance. 
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Electrical Arcing / Snapping

Reply #13 –
Just got off of the phone with Southwire, the makers of the SurgeGuard in my coach.  The technician confirmed that what I am hearing is the Surge Protector doing it's job. He explained that as consumption goes down in the middle of the night, voltage goes up. The device is designed to disengage at + or - 132 volts and because of it's age may be slightly out of calibration. He also said that the device is likely near the end of it's life and I may get only a couple of more years out of it.  The fact that the noise makes me jump out of bed probably means that my hearing is more sensitive than most.  He is probably right because my wife never heard it.  I will probably look into a replacement.

Thanks ro all for your insight.
Don & Sue
2009 NImbus 38
2020 Jeep Grand Cherokee toad

Re: Electrical Arcing / Snapping

Reply #14 –
Quote from: djpauls –
  In the middle of the night I woke up to a loud arcing sound and a bang.  It sounded like a shotgun going off.

Well if that's the sound of the surge protector doing its job I'd be looking into a replacement.  Sounds more like the sound of a clueless service rep.....  Arcs and bangs are not going to do your complex electronics any good. 
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS
 

Re: Electrical Arcing / Snapping

Reply #15 –
Quote from: Chuck Pearson –
Well if that's the sound of the surge protector doing its job I'd be looking into a replacement.  Sounds more like the sound of a clueless service rep.....  Arcs and bangs are not going to do your complex electronics any good. 

I'm still uncomfortable with this arcing banging stuff.  At this point, if it were my problem, the only time the electricity would be on was when I was home.  A good portion of my attention would be spent locating the problem.  I've had a pad mounted transformer "explode."  I've also had a 220V 3-phase line voltage short arc long enough to take out several computer surge protectors.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.