Great intro, thank you! I echo Steve's question about grounding when not connected to shore power. I'm looking to build a little battery system for a small travel trailer and don't want to fry myself. I'm looking at a small ~700W solar array and two 12V LFP batteries in parallel into a 24V AIO hybrid solar inverter.
Very informative series you have. Most of what you explain makes sense to me, what I don’t understand is how an RV can be grounded if it’s not connected to shore power. The reason I am asking is my sister-in-law has a camper that’s experiencing problems with the remotes used for the truma caravan movers. From the info you provided it appears there might be a problem with the grounding. But all of the problems she is experiencing with the 12v system are before she connects to shore power.
The remotes went out several times. She’s had trouble with fridge and ac but i think only the fridge is connected to the 12v system. This is what one RV service center said:
I don’t think its the battery, but i will confirm later today. The issue is with the remotes. She did have one tech look at, he said “Hot skin ground on coach 10-11 volts dc between any metal surface and ground. Likely an issue on the 12volt side leaking onto skin”. So there is likely current leakage.
Good afternoon team. I’m looking into a parasitic drain in a class A. They are dry camping. They have 700 watt solar. All power appears to be clean until you measure between neutral and ground. I measured 36 to 41 volts Ac.
If I shut inverter off it goes away.
In the power box grd and neutral are not bonded. Auto transfer switch is not bonded.
Unless the neutral and “ground” wires in a RV are bonded together it’s normal for there to be a floating voltage difference between them. While connected to shore power this N-G bond is supplied by the main service panel. When connected to an onboard generator this N-G bond is supplied by the ATS or generator itself. And when power is connected to a portable inverter generator this N-G bond can be provided by a generator bonding plug. Only the service panel neutral bond is actually “grounded” to earth via a ground rod at the service panel entrance. In all other cases this so called “ground” is actually a chassis ground, or what we call a “ground plane”. And that’s how all airplanes and cars are isolated from earth and “grounded” to their own chassis. The source of the confusion is that the word “ground” is used for a lot of different things that have nothing to do with “earth ground” at all.
As a boy of about 8 or 9 I was standing around while an electrician was trying to figure out why the pump on our water well on the farm wouldn’t work. I was standing in mud an inch or so deep with water puddles in cow tracks. I was wearing leather boots. I told my dad that my feet were getting shocked when I stepped in one area. They found a bad wire buried directly, no conduit or anything. It was buried, as I recall, a foot or more deep. With the standing water and mud the earth wasn’t totally getting rid of the current.
Obvious question is what about boondocking? There is no shore power connection to provide a ground but we seem to survive. It seems simple enough that 12V does not usually produce lethal shocks. But what about large solar arrays and high powered inverters? Mike, have you heard about situations in which people get shocked while boondocking?
Had to go check the manual on the inverter. It appears to also have a neutral-ground bond. Basically that neutral-ground bond needs to be at or near the source of the power, so that stray/leaked voltages can get back to the neutral connection at the source. (If I have missed anything Mike, please chime in.)
My on board generator IS neutral-ground bonded, connected thru the automatic transfer switch (ATS)(as I understand things) so when I am connected to shore power, the ECG is connected to the green wire of the shore power plug, the neutral to the white wire. When on generator, the ATS contactors connect to the generator and disconnect from the shore power. The neutral-ground bond is in the generator, and thus only bonds to the chassis when the ATS is connected to the generator .
Great intro, thank you! I echo Steve's question about grounding when not connected to shore power. I'm looking to build a little battery system for a small travel trailer and don't want to fry myself. I'm looking at a small ~700W solar array and two 12V LFP batteries in parallel into a 24V AIO hybrid solar inverter.
Hello Mike,
Very informative series you have. Most of what you explain makes sense to me, what I don’t understand is how an RV can be grounded if it’s not connected to shore power. The reason I am asking is my sister-in-law has a camper that’s experiencing problems with the remotes used for the truma caravan movers. From the info you provided it appears there might be a problem with the grounding. But all of the problems she is experiencing with the 12v system are before she connects to shore power.
Exactly what problems is she experiencing?
The remotes went out several times. She’s had trouble with fridge and ac but i think only the fridge is connected to the 12v system. This is what one RV service center said:
Is her battery voltage showing full charge? Does she have a voltage or charge indicator? Could be a dead or discharged battery.
Unless she has a large battery and inverter the air conditioner is not going to run from battery power. It needs shore power or a generator.
I don’t think its the battery, but i will confirm later today. The issue is with the remotes. She did have one tech look at, he said “Hot skin ground on coach 10-11 volts dc between any metal surface and ground. Likely an issue on the 12volt side leaking onto skin”. So there is likely current leakage.
That makes no sense at all. Please email me your phone number to mike@noshockzone.org to discuss.
I just did, call me anytime
Good afternoon team. I’m looking into a parasitic drain in a class A. They are dry camping. They have 700 watt solar. All power appears to be clean until you measure between neutral and ground. I measured 36 to 41 volts Ac.
If I shut inverter off it goes away.
In the power box grd and neutral are not bonded. Auto transfer switch is not bonded.
Why would neutral be carrying so much voltage.
Unless the neutral and “ground” wires in a RV are bonded together it’s normal for there to be a floating voltage difference between them. While connected to shore power this N-G bond is supplied by the main service panel. When connected to an onboard generator this N-G bond is supplied by the ATS or generator itself. And when power is connected to a portable inverter generator this N-G bond can be provided by a generator bonding plug. Only the service panel neutral bond is actually “grounded” to earth via a ground rod at the service panel entrance. In all other cases this so called “ground” is actually a chassis ground, or what we call a “ground plane”. And that’s how all airplanes and cars are isolated from earth and “grounded” to their own chassis. The source of the confusion is that the word “ground” is used for a lot of different things that have nothing to do with “earth ground” at all.
As a boy of about 8 or 9 I was standing around while an electrician was trying to figure out why the pump on our water well on the farm wouldn’t work. I was standing in mud an inch or so deep with water puddles in cow tracks. I was wearing leather boots. I told my dad that my feet were getting shocked when I stepped in one area. They found a bad wire buried directly, no conduit or anything. It was buried, as I recall, a foot or more deep. With the standing water and mud the earth wasn’t totally getting rid of the current.
Once again great article.
Here is what I found at my current Rv park. Two wire incoming ground lug. One #6 bare, one #6 in a sheath.
No strap to ground lug. No ground straps to any of the receptacles.
Park says been that way since 2006.
Can you email me a picture? Please send to mike@noshockzone.org
Obvious question is what about boondocking? There is no shore power connection to provide a ground but we seem to survive. It seems simple enough that 12V does not usually produce lethal shocks. But what about large solar arrays and high powered inverters? Mike, have you heard about situations in which people get shocked while boondocking?
I’ve written about this a good bit and will repost a few articles.
Had to go check the manual on the inverter. It appears to also have a neutral-ground bond. Basically that neutral-ground bond needs to be at or near the source of the power, so that stray/leaked voltages can get back to the neutral connection at the source. (If I have missed anything Mike, please chime in.)
My on board generator IS neutral-ground bonded, connected thru the automatic transfer switch (ATS)(as I understand things) so when I am connected to shore power, the ECG is connected to the green wire of the shore power plug, the neutral to the white wire. When on generator, the ATS contactors connect to the generator and disconnect from the shore power. The neutral-ground bond is in the generator, and thus only bonds to the chassis when the ATS is connected to the generator .
That’s exactly how an on-board generator is supposed to work.
I was mostly trying to help you teach. Don't know if I accomplished that.