Intermittent Open Ground (Surge Guard 34950)

**orbsah** · 12-27-2023, 05:02 PM

We've been using this Surge Guard 34950 for almost 4 years now without any problems. However an issue came up at our winter site in AZ and I'm wondering if anyone can shed any light.

We've been in this one site since mid-September and over the past 4'ish months, we've lost power due to an "open ground" fault maybe about 6'ish times (once every few weeks). When I turn off, then back on the breaker at the pedestal, everything is fine. Seems to be a random occurrence and doesn't seem to matter if there's a heavy load on the system or not. Fortunately our fridge automatically switches to LP mode so we haven't lost any food. This last time we left the rig for about 5 days and when we returned, the power was off again with the open ground fault. Based on the battery status, I estimate the power was lost about 2 days before we returned. The only thing that was running was the fridge (on AC when we left, on LP when we returned). Couple questions. . . .

#1 : Does the "open ground" fault indicator verify an issue upstream (pedestal/park power)? Or does it also check downstream (coach power)? Or both? The manual isn't clear on this.

#2 : Shouldn't an open ground stay open? In other words, if there's an open ground somewhere, resetting the circuit breakers should just result in the same fault repeated, right? Is there such a thing as "intermittent open ground"?

I checked all the 110V outlets in the rig and at the pedestal and all seems fine now. I've also wiggled the 50A power cord between the pedestal and rig to see if there are any loose connections.

I suspect an issue with the park power but I can't duplicate the situation. Any suggestions?

PS: I've also reached out the Southwire - waiting for their response.

**xrated** · 12-27-2023, 06:02 PM

An intermittent open ground sounds like a loose ground connection somewhere, very possibly in the shore power pedestal. Turning the shore power breakers off, then on causes at least some vibration of the box and could possibly be the source of the Intermittent part of it. Can the park send over a qualified Electrician to check all the connections on the recept. that you plug your shore power into? That would be a great place to start. Remember, when you are flipping the main breakers on/off, you are not physically interrupting the electrical ground, they simply open/close the two line conductors for the 50A shore power.....it's the "vibration" from the movement that may be causing it to make/break contact for the ground connection if there is a loose terminal screw somewhere.

**orbsah** · 12-27-2023, 06:06 PM

Originally Posted by xrated

An intermittent open ground sounds like a loose ground connection somewhere, very possibly in the shore power pedestal. Turning the shore power breakers off, then on causes at least some vibration of the box and could possibly be the source of the Intermittent part of it. Can the park send over a qualified Electrician to check all the connections on the recept. that you plug your shore power into? That would be a great place to start. Remember, when you are flipping the main breakers on/off, you are not physically interrupting the electrical ground, they simply open/close the two line conductors for the 50A shore power.....it's the "vibration" from the movement that may be causing it to make/break contact for the ground connection if there is a loose terminal screw somewhere.

Yes, loose connection at the pedestal is my suspicion and I'm going to contact the park - that's the next step. However I did wiggle/shake the pedestal and power cord and couldn't duplicate the fault. Thanks!

**LMagelitz** · 12-27-2023, 06:44 PM

I can’t speak for the Surge Guard specifically, but these devices are typically meant to check the integrity of shore power, so the open ground would be upstream. It may be nothing more than the receptacle blades for the ground spade not making good contact anymore.

**jkwilson** · 12-27-2023, 08:17 PM

Upstream. The ground should be 120V from both hots, and I’m sure the EMS uses that measurement as the test for ground continuity to the panel. Could be the outlet in the box, the wiring behind it or any junction in the ground wire between the Surge Guard and the service panel.

Intermittent stuff is among the hardest things to track down. Visual inspection followed by connecting a data logger to the circuit in question is about all even pros will be able to do.

If you get an electrician to the site, if nothing seems obvious in the pedestal, you might ask if he’ll check the ground bus in the panel.

**orbsah** · 03-20-2024, 06:26 PM

I apologize for not following up on this (seeing another related thread). The park maintenance guy came out, tightened a few connections but otherwise couldn’t find any obvious issue. A couple weeks later I got the open ground again. Called the park and this time they sent out a real electrician. He disassembled, cleaned and tightened more connections with no obvious issue found. A few weeks later, I got the open ground again. For about 3’ish weeks I was able to plug into an adjoining site and no problems. So I plugged back into our pedestal and about a month later ( last weekend), I got the open ground again. These are probably the original pedestals that were installed in the 70’s.

Yes, it’s kind of annoying but when the fault happens, the fridge kicks to LP so no harm there. We’ve been here since September and rolling out May 1. If we have open ground issues during our travels this summer, I’ll be convinced there’s a problem with the surge guard. For the next 5 weeks or so we’ll just live with it.