Testing Shows all Outlets have "Bad Ground"

[dngaul]

I discovered that all the outlets in my RV test to have a "bad ground". Since the outlets involve multiple circuits, I assume that the problem is associated with the main ground. The shore power outlet is ok and the ground on the main bus is solid and clean. All of the outlets still function. What are the possibilities?

My RV is a 2002 Pace Arrow 37A with 30 amp service.

[j-d]

Bobbo wrote:
...box where the shore cord was wire nut connected to the RV wiring. The ground wire in the wire nut was not making contact...

Good tip! That Stranded-to-Hard Wire interface has been a point of failure in RV's

[Bobbo]

When I found that situation in my previous RV, I traced it down to the box where the shore cord was wire nut connected to the RV wiring. The ground wire in the wire nut was not making contact.

[wa8yxm]

If ALL the outlets test bad ground then here is the suspect list:
1: You are running on either Generator or INverter power.

Both Generators and inverters NEED NOT have the safety ground. on some you may choose to bond neutral to ground but it is optional.. Others not even an option
The ground is simply N/C (not connected)

2: Bad ground: Shore power outlet (The one the RV is plugged into)
3: Broken connnection, RV Plug..
3-4-5-6
If a detchable c ord, the outlet, the inlet
If an Auto transfer switch, the switch
The ground lead on the power distribution panel

And any wire between plug and panel.

NOTE: Suspectes listed in order of encounter. not in order of which is nmost likely though the park outlet and the RV's main plug are 1 and 2. on both liting methods.

If you have any adapters (IE 50-30 or 30-15) Include those between park and plug as well.

[MEXICOWANDERER]

Jumper cables. Clamp one end to bumper. Lay other end on earth. Pour glass of water on it. Ground warning now off? You have problems in breaker box cable or pedestal.

[Sam_Spade]

dngaul wrote:
Larry Cad - Yes, I'm using 3-light plug-in tester that shows the 6 possibilities. I am plugged into a campground shore power.

With an appropriate adapter, plug your little tester directly into the 30A outlet at the pole. Also test the regular 15 amp outlet at the pole if there is one.

That should pretty much tell the story.

[CA_Traveler]

Use a 30/20 adapter and test the pedestal with you house hold tester. Testing the pedestal before you plug in is a good safety precaution.

I've found reverse polarity and open grounds on 30A pedestals.

[MrWizard]

if you have an ON Board built in generator

testing with genny on, shore unplugged, may show a different result

testing with a 'portable' generator often shows open ground those test lights
because the neutral is bonded in the generator

[time2roll]

OK so most test meters have short leads. Remove the cord from the pedestal. Bring it around to the front door or inside next to the breaker panel. Use the meter to measure ohms from the ground pin of the plug to the ground bus in the RV. Value should be very close to zero. Hopefully it reaches around far enough inside so that it is easy to check.

[dngaul]

Larry Cad - Yes, I'm using 3-light plug-in tester that shows the 6 possibilities. I am plugged into a campground shore power. I asked campground maintenance to test the shore power plug-in. Seems like testing with generator power would be a good idea.
Ray - I did check all of the connections in the breaker box
time2roll - I don't understand " Pull the plug around inside ..."

[ktmrfs]

If it's at a campground, there may be an open ground at the site. I've had my EMS indicate open ground at several campsites. mostly because the 30A outlets are used a lot, and end up being marginal. In all cases I notified the campground, they came out an looked, and sure enough either the ground from the panel was bad, or the plug was bad.

If it's at your house, then it is more likely that the problem is in the trailer.

[RoyB]

larry cad wrote:

Keep in mind, the breaker panel in your RV is considered a "sub panel" for NEC purposes. That means the ground and the neutral are not connected together at the RV, nor at the campground power pole. The neutral to ground connection is only made at the campground main breaker panel.

In addition to this my WFCO WF-8900 Power Distribution Center has a NEUTRAL BUS BAR connection to all NEUTRAL connections and passes this on to the NEUTRAL lead of the shore power cable. This NEUTRAL BUS BAR is isolated from the trailer FRAME ground.

I also have a second GROUND BUS BAR where all of the GROUND CONNECTION from the ROMEX cable feeding everything is tied to and this is passed on to the GROUND wire of the Shore Power Cable. The difference here is the BUS BAR also goes directly to the WF-8900 Chassis Gnd connection which is also going to the trailer frame ground with a solid wire...

You can see this here on this WF-8700 main frame drawing...


This is how the GREEN wire coming from the Shore Power cable goes to the trailer skin frame ground on my trailer...

Roy Ken

[Harvard]

Are you using any extension cords OR adaptors ??

[time2roll]

Pull the plug around inside and check continuity from the pin to the bus.

[Ray_IN]

How long since you opened the RV breaker box and tightened all the screws holding wires? A rolling earthquake vibrates wire connections loose quite often. I check mine every year and usually find at least one that tightens a bit.
OF COURSE, DISCONNECT FROM ALL 120VAC POWER FIRST!