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Energizing earth

palmer

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Jul 24, 2021
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I am trying to figure out the problem with my solar set up everything in this setup seems to work, however, on one branch of the circuit from neutral to ground I have 16.6 volts and 131.9 volts on the ground to hot, and on the other branch from neutral to ground I have 16.9 v and hot to ground I have 108.4 volts. I have the growatt 5000, split phase transformer, and a standard squared D breaker box.



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I am having this problem where I am somehow energizing the ground. I have done something that has led to having a potential between the dirt and both neutral and hot with the larger potential on hot. I don’t know what is causing this to happen, however, whenever I plug anything tool that has metal housing I will receive a shock from this potential even it it is plugged into extension cords 100+ feet away. I have tried isolating everything including disconnecting the solar panels, however, this potential still exists from the inverter

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The neutral and ground are typically bonded at the load center, and usually earthed near the service entrance (assuming you're in the U.S.).
So, going hot-to-dirt is the same as hot-to-neutral, but with a lot of resistance.

The real key is that you're getting a shock. The housing of a metallic tool is typically grounded so that if the hot wire comes loose and touches the case it will short and trip the breaker. That prevents you from getting shocked.

So my guess would be that somewhere in the wiring, the hot and neutral wires flipped and the ground isn't connected or making good contact either in the wiring, the extension cord, or the tool (if it was, it would trip the breaker). So, when you touch the tool you become the circuit in hot-to-ground and Zzzzt!

Hope that helps, please let us know what you find.
 
The neutral and ground are typically bonded at the load center, and usually earthed near the service entrance (assuming you're in the U.S.).
So, going hot-to-dirt is the same as hot-to-neutral, but with a lot of resistance.

The real key is that you're getting a shock. The housing of a metallic tool is typically grounded so that if the hot wire comes loose and touches the case it will short and trip the breaker. That prevents you from getting shocked.

So my guess would be that somewhere in the wiring, the hot and neutral wires flipped and the ground isn't connected or making good contact either in the wiring, the extension cord, or the tool (if it was, it would trip the breaker). So, when you touch the tool you become the circuit in hot-to-ground and Zzzzt!

Hope that helps, please let us know what you find.
Thank you for your help! I just measured the resistance from hot to earth and I have around 4500-5500 ohms. I am not sure what the typical resistance is so not sure if this is high or low. In my solar setup I have a split phase transformer producing my neutral and from hot to hot I have a potential of 240 so I would think that is wired correctly. I have attached a photo of my equipment opened up if by chance you can tell anything that is wired wrong.
 

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How is your system connected to the earth ground rod?
I cannot tell in the pictures if the Neutral is bonded to the Ground or not.
Can you show your wiring diagram?
 
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... I would think that is wired correctly. I have attached a photo of my equipment opened up if by chance you can tell anything that is wired wrong.
Small chance to find it remotely via photos (e.g., could be cross-wired in the extension cord).

Keep in mind my guess might not be right. A way you can check is by testing the voltage between the extension cord end that gives the shock and the inverter (e.g., hot-to-hot/ground-to-ground/neutral-to-ground should be ~zero volts and inverter-hot to extension-cord-ground should be ~120V).

Please let us know what you find!
 
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What about a Ground Bonding Connector in the inverter ?
The different models of Inverters / AIO's etc handle this differently, some are Multi-Use as in Vehicle or Residential and therefore come with a Bonding Wire that has to be either connected for Vehicle & Disconnected for static land-based use.

Also a lesson learned (not your issue) is that not ALL gcfi plugs behave well with solar systems.
Always use an AC Plug Tester not just a DMM/DVOM.

An extract from my Samlex Docs
3.11 GROUNDING TO EARTH OR TO OTHER DESIGNATED GROUND i
INFO Please read following on-line White Papers for complete understanding of Grounding at www. samlexamerica.com (Home > Support > White Papers):
• “Grounded Electrical Power Distribution" • “Grounding System and Lightning / Ground Fault Protection” Grounding means connecting (bonding) to Earth Ground or to the other designated Ground. For example, in a motorhome / caravan, the metal frame of the motorhome / caravan is normally designated as the Negative DC Ground / RV Ground. Similarly, all metal portions of boats and marine craft are bonded together and called Boat Ground. Grounding is required for (i) protection against damage due to lightning strike and (ii) protection against electric shock due to “Ground Fault”. In case of EVO, “Ground Fault” may occur due to inadvertent contact between an energized ungrounded current carrying conductor and exposed metal surface resulting in voltage getting fed to (i) the metal chassis of the EVOTM or (ii) to the metal chassis of the devices connected to EVOTM or (iii) to the metal frame/ chassis in an RV / motorhome / caravan. When this energized exposed surface is touched, the voltage will drive current through the body to Earth Ground producing electric shock. When properly grounded to Earth Ground (or Frame / Chassis Ground in motorhome or caravan), the Leakage Current Protection Device (like RCD, GFCI etc.) or Over Current Protection Device (like Circuit Breaker or Fuse) will trip and interrupt the circuit feeding power from the AC source (EVOTM / Grid / Generator) or the DC source (12V / 24V battery). Proper grounding will ensure that all exposed metal surfaces will have equal potential and will be bonded to (i) a single common Earth Ground point i.e. the Ground Rod / buried metallic water / gas pipe at the premises or (ii) the Frame / Chassis Ground in a motorhome / caravan
 
BTW, What is this Growatt model? Is it also connected to the grid for charging from utility (if that function is available)?
 
Looks like very very dangerous things are going on. I highly recommend to get asap a professional checking/fixing that stuff!
 
Many inverters have EMI filtering caps between both hot and neutral to case ground. Only like a 0.1 uF. If you leave neutral floating then you will get voltage measured from neutral to case ground. It won't support much of any load current but you will read a voltage on high impedance voltmeter to case ground..

If you ground neutral (and inverter case) then your DVM will read zero on neutral and near full AC voltage from hot to ground.
 
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