Hello all,
I have researched this information for quite a bit but didnt find anything that answers my question or I didnt understand it.
I am in the process of converting a cargo trailer into a small camper with storage in the back to host my paramotor engine (awesome sport, if you dont know it, look it up on youtube).
There are 500W solar on the roof with a BougeRV MPPT connected to a 100Ah Vatrer 12V battery. On it I have a 1100W Krieger inverter to feed a single outlet I am planning on using solely for a small 800W kettle on occasion. I have designed my system to be sufficient for unlimited of time in summer and 3 days in winter with a small fridge and a diesel heater. This is not my first build/conversion.
However there is something new this time, I've never done before which is to not have shore power inside the camper since I am planning on boondocking 100%. Since I am in PNW, I can't necessarily rely on my solar to charge my batteries on 2 consecutive trips, or even for longer trips in winter, I might have to top off on shore since the car wont be able to charge much (I dont have a DC-DC yet but have all the wiring etc. ready). I therefore have a 20A battery charger connected to shore through a 110V breaker I added inside my camper (as double rubber).
The scenario I imagine is being on shore to top-off my battery while needing my kettle inside. I'll go through my inverter, no problem. (Yes I know, I could use some sort of a Y shore line splitter to charge my camper while using shore power outside, but that does not illustrate my scenario). But where I struggle a lot, for some weird reason, is to figure out bonding/grounding.
If I had a regular install, I'd have a transfer switch which would change bonding from inverter/chassis to shore ground to keep a single bonding. In this case, the inverter would not provide any power to the RV and all would come through shore. Grounding/bonding is clear. But here, since I am using shore to only energize my charger I'm getting confused. In the unlikely event that the cable running from my outside plug to my charger would get damaged and energize my camper, I'd obviously need to bond my chassis to shore ground to be protected. But since my 110V inside my camper is coming from my inverter, I'd need also a neutral-ground bonding for the inverter. The Krieger has a sticker on the back which says "Neutral floating" and "DC input isolated from AC output".
On the inverter, I have conductivity between AC ground and the ground lug, no continuity between AC neutral and ground lug/DC negative, conductivity between DC negative and ground lug.
Any idea what I should do? I can't see an option but to somehow disable my inverter while I'm on shore and do a regular distribution with a transfer switch and all that jazz. But for space, weight and simplicity reasons, I'd like to not do that.
PS: my shore connection on my RV is clearly setup as an unnecessary convenience feature. I could leave the whole charger situation outside and only run the 12V in. I'm doing this for the convenience of being able to charge at home while keeping all doors locked and tight. I also imagined of course a similar setup where I would just run an extension cord to my charger (which is basically what I am doing, only a piece of the extension cord is part of my RV). In this case, if my extension cord was damaged and would create a hot skin, I'd get electrocuted when touching the camper (outside) since I would close the loop with the ground, if the receptacle is not GFCI/RCD protected (btw, Im european and in Europe we have RCD on the main breaker for the whole panel then all breakers are RCD at the panel directly protecting from the source to the point of consumption - one thing I dislike about the US electrical system is that RCDs are not everywhere).
So the scenario I explained here above is similar to my damaged extension cord example, isn't it?
Hence I shouldnt be worried about it. But still, I want to do better and protect myself from an electrocution when connected to shore while keeping my inverter running.
I appreciate your help understanding my bonding/grounding issue.
I have researched this information for quite a bit but didnt find anything that answers my question or I didnt understand it.
I am in the process of converting a cargo trailer into a small camper with storage in the back to host my paramotor engine (awesome sport, if you dont know it, look it up on youtube).
There are 500W solar on the roof with a BougeRV MPPT connected to a 100Ah Vatrer 12V battery. On it I have a 1100W Krieger inverter to feed a single outlet I am planning on using solely for a small 800W kettle on occasion. I have designed my system to be sufficient for unlimited of time in summer and 3 days in winter with a small fridge and a diesel heater. This is not my first build/conversion.
However there is something new this time, I've never done before which is to not have shore power inside the camper since I am planning on boondocking 100%. Since I am in PNW, I can't necessarily rely on my solar to charge my batteries on 2 consecutive trips, or even for longer trips in winter, I might have to top off on shore since the car wont be able to charge much (I dont have a DC-DC yet but have all the wiring etc. ready). I therefore have a 20A battery charger connected to shore through a 110V breaker I added inside my camper (as double rubber).
The scenario I imagine is being on shore to top-off my battery while needing my kettle inside. I'll go through my inverter, no problem. (Yes I know, I could use some sort of a Y shore line splitter to charge my camper while using shore power outside, but that does not illustrate my scenario). But where I struggle a lot, for some weird reason, is to figure out bonding/grounding.
If I had a regular install, I'd have a transfer switch which would change bonding from inverter/chassis to shore ground to keep a single bonding. In this case, the inverter would not provide any power to the RV and all would come through shore. Grounding/bonding is clear. But here, since I am using shore to only energize my charger I'm getting confused. In the unlikely event that the cable running from my outside plug to my charger would get damaged and energize my camper, I'd obviously need to bond my chassis to shore ground to be protected. But since my 110V inside my camper is coming from my inverter, I'd need also a neutral-ground bonding for the inverter. The Krieger has a sticker on the back which says "Neutral floating" and "DC input isolated from AC output".
On the inverter, I have conductivity between AC ground and the ground lug, no continuity between AC neutral and ground lug/DC negative, conductivity between DC negative and ground lug.
Any idea what I should do? I can't see an option but to somehow disable my inverter while I'm on shore and do a regular distribution with a transfer switch and all that jazz. But for space, weight and simplicity reasons, I'd like to not do that.
PS: my shore connection on my RV is clearly setup as an unnecessary convenience feature. I could leave the whole charger situation outside and only run the 12V in. I'm doing this for the convenience of being able to charge at home while keeping all doors locked and tight. I also imagined of course a similar setup where I would just run an extension cord to my charger (which is basically what I am doing, only a piece of the extension cord is part of my RV). In this case, if my extension cord was damaged and would create a hot skin, I'd get electrocuted when touching the camper (outside) since I would close the loop with the ground, if the receptacle is not GFCI/RCD protected (btw, Im european and in Europe we have RCD on the main breaker for the whole panel then all breakers are RCD at the panel directly protecting from the source to the point of consumption - one thing I dislike about the US electrical system is that RCDs are not everywhere).
So the scenario I explained here above is similar to my damaged extension cord example, isn't it?
Hence I shouldnt be worried about it. But still, I want to do better and protect myself from an electrocution when connected to shore while keeping my inverter running.
I appreciate your help understanding my bonding/grounding issue.
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