HELP AC Outlets blowing devices!

[SDrummer]

Hello all,

I am currently living in a River Canyon 34RLQS0 5th Wheel that is hooked up to electrical power. I am having a odd issue with the electrical in the trailer. Some of the GFI outlets are blowing electrical devices when they are plugged in. Yesterday we plugged a toaster into the kitchen and it started smoking without even turning the device on. I also plugged my laptop AC adapter into the GFI outlet in the bedroom and it worked for about 2 minutes before blowing. The AC adapter does not give out any voltage and I verified this at my work.

The trailer has has issues in the past as it has blown the bedroom TV and kitchen Microwave as well.

I have measured the voltage on the plugs and they range from 110v-117v.

Today I tested all of the outlets with a GFI tester and they all read good indicating there are no line, neutral, or ground wires crossed.

The bizzare thing is that the plugs seem like they decide which devices they want to fry. I am currently running my heater and charging my phone on the same plug that blew my laptop AC adapter yesterday.

Any help is appreciated as I worried about plugging anything into the walls fearing it will blow the device.

Thanks

[john_bet]

BurbMan wrote:
Interesting stuff! It never occurred to me that a faulty neutral could create voltage fluctuations in a split phase set up like a home or RV but makes perfect sense the way it's explained.

Interested to see if OP can locate the problem, and if so whether it was in the RV or on the supply side.

Previous S&B house in NY had a 12/3 running from the main panel to the 2FL where it split into two 15A bedroom circuits with a shared neutral. Was AL wire to boot!

Found this from a Square D tech bulletin, note second bullet:

There are several significant disadvantages to be found in the practice of
sharing neutrals:
• On two-pole common-trip circuit breakers, both circuits are interrupted
during any type of fault. If a shared neutral circuit feeds many rooms,
then all rooms lose power if a fault occurs in any one room. If a shared
neutral circuit feeds receptacles and lights, both will lose power with a
fault on either one.
• If the homerun neutral is lost, the connected loads are subject to
voltages varying from 0 V to 240 V (line-to-line). The likely result
from this is severe damage to any connected devices due to extreme
under- and over-voltage conditions.
• On two-pole independent-trip circuit breakers, one may find hot wires
in a junction box that was presumed dead. One cannot overemphasize
how dangerous this would be. If one of the shared neutral circuits were to
trip due to a short-circuit or overload, the other circuit would remain hot.
Anyone servicing any device in that junction box may be exposed to
live conductors.

The NEC still allows shared neutral circuits, but I believe it now requires them to be on a common-trip double breaker to avoid the hazard identified in the 3rd bullet above.

This is the reason you find a double pole c/b on the pedestal and in your trailers load center for 50 amp service. Been that way for decades.

[BurbMan]

SDrummer wrote:
So I went ahead and unplugged everything from the outlets and turned off all the lights. I measured the voltage with nothing on and it was 117V.

I then turned on the AC and measured the voltage again at the same outlet and it increased to 118.5V.

I checked all the outlets and on the ones I could get a reading it was the same around 118.5V.

However on two of the GFI plugs, the one in the bedroom and kitchen, The voltage readings kept fluctuating between 0V & 5V. I then turned off the AC and measured the voltage however the voltage did not change and was still fluctuating between 0 & 5V.

My girlfriend had been using the plug in the bedroom for her curling iron just fine thirty minutes prior to me checking the voltage.

Exactly...if you happen to plug in when the load between both branches is balanced, no problem....plug in when something is drawing current and unbalancing the load and *poof*. Like playing Russian roulette with your appliances. Next time you get ready to plug something in have your GF ask you, "Do ya feel lucky today punk? Well, do ya?"

[BurbMan]

Interesting stuff! It never occurred to me that a faulty neutral could create voltage fluctuations in a split phase set up like a home or RV but makes perfect sense the way it's explained.

Interested to see if OP can locate the problem, and if so whether it was in the RV or on the supply side.

Previous S&B house in NY had a 12/3 running from the main panel to the 2FL where it split into two 15A bedroom circuits with a shared neutral. Was AL wire to boot!

Found this from a Square D tech bulletin, note second bullet:

There are several significant disadvantages to be found in the practice of
sharing neutrals:
• On two-pole common-trip circuit breakers, both circuits are interrupted
during any type of fault. If a shared neutral circuit feeds many rooms,
then all rooms lose power if a fault occurs in any one room. If a shared
neutral circuit feeds receptacles and lights, both will lose power with a
fault on either one.
• If the homerun neutral is lost, the connected loads are subject to
voltages varying from 0 V to 240 V (line-to-line). The likely result
from this is severe damage to any connected devices due to extreme
under- and over-voltage conditions.
• On two-pole independent-trip circuit breakers, one may find hot wires
in a junction box that was presumed dead. One cannot overemphasize
how dangerous this would be. If one of the shared neutral circuits were to
trip due to a short-circuit or overload, the other circuit would remain hot.
Anyone servicing any device in that junction box may be exposed to
live conductors.

The NEC still allows shared neutral circuits, but I believe it now requires them to be on a common-trip double breaker to avoid the hazard identified in the 3rd bullet above.

[CA_Traveler]

Yes the 2 hots and neutral are sized to handle a maximum of 50A.

My last 50A rig had a Onan 7500 QD gen which had 2 120V circuits (ie no 240V). The neutral wire from the gen to the ATS and to the panel was one size larger to handle the 62A.

[wnjj]

wa8yxm wrote:
If both hots were on the same leg.. Then he'd not have this problem with imbalance, and if he had an open neutral he'd be seeing LOW voltages all around.

NO, that's it not the problem. Please consider what you are typing before misdirecting.

That said: What you typed is 100% correct and true.. Just not the problem in this thread.

Where did anyone say this was the problem? Sorry, we got off topic.

[wnjj]

CA Traveler wrote:

wnjj wrote:

JimM68 wrote:
ok, read the first half of the first page. Rig is a 50 amps with an open neutral.
OP is not qualified to fix this.

Things will continue to blow up. Recommend an electrician. unfortunately, most electronic / computer types just have no clue about a/c power, particularly 2 phase stuff. (and yes, generally 50 amp rv power is 2 phase, even though it doesn't need to be and is not specified to be.

If 50 amp RV power uses a 4-pin plug, it had better be 2-phase. If both hots are on the same phase the neutral wire needs to handle twice the current which it likely isn't capable of. The only safe way to use such a system with a neutral wire sized for 50 amps is to use a double pole 25 amp breaker.

Both of these posts are incorrect.

50A RV power is in fact single phase. 240/120V power comes from a SINGLE center tapped winding on a transformer with the center tap being the neutral. As such current in the winding and hence both hot legs flows in one direction or the other and can only be single phase.

The neutral does in fact handle only the difference of the two hot leg currents which with the dual 50A CB restricts the neutral current to 50A in this SINGLE PHASE system.

50A RV power is not multiple phase power like you might find with a Y or Delta configuration.

50A RV power is also the same at the typical household power except that the typical home has a bigger panel like 200A. Otherwise both are single phase.

It's very common but incorrect to refer to 50A RV power as 2 phase. Split phase is a good description of 50A power.

Ok. What I called 2-phase is actually called split-phase, but what I wrote about the wire sizes is still true which is the important point. Split-phase operates like the now obsolete 2-phase did except 180 degrees out of phase instead of 90.

In both cases the current flowing in each of the hot wires is out of phase with each other (hence why I mistakenly called it 2-phase). It looks to me like the only reason we don't call it 2-phase today is simply to avoid confusion with legacy 2-phase (90 degree) systems or maybe the technical definition of phase is that 180 is considered the same as 0.

Obviously 180 degrees allows for full neutral sharing where 90 doesn't. Close enough?

Regardless, not the point of this thread since the OP's trailer is wired for split phase.

[CA_Traveler]

wnjj wrote:

JimM68 wrote:
ok, read the first half of the first page. Rig is a 50 amps with an open neutral.
OP is not qualified to fix this.

Things will continue to blow up. Recommend an electrician. unfortunately, most electronic / computer types just have no clue about a/c power, particularly 2 phase stuff. (and yes, generally 50 amp rv power is 2 phase, even though it doesn't need to be and is not specified to be.

If 50 amp RV power uses a 4-pin plug, it had better be 2-phase. If both hots are on the same phase the neutral wire needs to handle twice the current which it likely isn't capable of. The only safe way to use such a system with a neutral wire sized for 50 amps is to use a double pole 25 amp breaker.

Both of these posts are incorrect.

50A RV power is in fact single phase. 240/120V power comes from a SINGLE center tapped winding on a transformer with the center tap being the neutral. As such current in the winding and hence both hot legs flows in one direction or the other and can only be single phase.

The neutral does in fact handle only the difference of the two hot leg currents which with the dual 50A CB restricts the neutral current to 50A in this SINGLE PHASE system.

50A RV power is not multiple phase power like you might find with a Y or Delta configuration.

50A RV power is also the same at the typical household power except that the typical home has a bigger panel like 200A. Otherwise both are single phase.

It's very common but incorrect to refer to 50A RV power as 2 phase. Split phase is a good description of 50A power.

[wa8yxm]

If both hots were on the same leg.. Then he'd not have this problem with imbalance, and if he had an open neutral he'd be seeing LOW voltages all around.

NO, that's it not the problem. Please consider what you are typing before misdirecting.

That said: What you typed is 100% correct and true.. Just not the problem in this thread.

[wnjj]

JimM68 wrote:
ok, read the first half of the first page. Rig is a 50 amps with an open neutral.
OP is not qualified to fix this.

Things will continue to blow up. Recommend an electrician. unfortunately, most electronic / computer types just have no clue about a/c power, particularly 2 phase stuff. (and yes, generally 50 amp rv power is 2 phase, even though it doesn't need to be and is not specified to be.

If 50 amp RV power uses a 4-pin plug, it had better be 2-phase. If both hots are on the same phase the neutral wire needs to handle twice the current which it likely isn't capable of. The only safe way to use such a system with a neutral wire sized for 50 amps is to use a double pole 25 amp breaker.

[oilslick]

Just turn off the main breaker and physically check each neutral connection out to the post, if all ok then start in the trailer.

[wa8yxm]

Regarding RV Tech v/s Electrician.

First: I will comment on the "Not all are qualified" this is true, Qualified means you took a class and optionally wrote a test and passed. Some schools guarantee you will pass. Kind of like Driver's ED. As you know not all Driver's are qualified (A fact of which I'm kind of glad being a retired police dispatcher.. Why is this.. If not for bad drivers, My services as dispatcher would not have been needed for the first 14.5 years of my employment (it was a traffic post where I worked).

Likewise not all electricians know the answer to the question which was answered in the movie "Birds Do It" staring Jerry Lewis with "Of course I know the difference, you need a shovel to dig a hole in the ground") the question we never actually heard, they cut away as the professor said DO YOU KNOW THE....)

But... in this case. An GOOD RV technician (Note I said GOOD, not qualified, though a GOOD one will be qualified) very likely knows RV systems better than a sticks & Bricks electrician. Though in this case.. Either one may help.

IN my case I'm a fair ELECTRONICS tech by training, Thus I can occasionally trouble shoot electrical issues.. Since that is a very much related field.

[SCVJeff]

Wayne Dohnal wrote:

generally 50 amp rv power is 2 phase,

Wow, you're likely to get a few pages of flogging for saying this. Been there, done that. It's even worse than saying "hot water heater"!

But thats redundant... 🙂

[CA_Traveler]

Well it's rather common to refer to 50A RV power as 2 phase. It is in fact single phase and the term split phase is a reasonable description...

OK Wayne I rose to the bait...

[Wayne_Dohnal]

generally 50 amp rv power is 2 phase,

Wow, you're likely to get a few pages of flogging for saying this. Been there, done that. It's even worse than saying "hot water heater"!

[JimM68]

ok, read the first half of the first page. Rig is a 50 amps with an open neutral.
OP is not qualified to fix this.

Things will continue to blow up. Recommend an electrician. unfortunately, most electronic / computer types just have no clue about a/c power, particularly 2 phase stuff. (and yes, generally 50 amp rv power is 2 phase, even though it doesn't need to be and is not specified to be.