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Grounding panels on RV roof?
- Thread starter chaostactics
- Start date
12VoltInstalls
life passes by too quickly to not live in freedom
The Van DeGraff effect is what would protect you if anything.
A lightning bolt that travels 10-15 miles before discharging to earth is not going to be disabled in the slightest by a few inches of rubber separating one from the dirt.
But it will course/travel around a metal cage to the source of the static charge differential.
RCinFLA
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When plugged into shore power your RV frame and all external metal should be grounded to shore power ground.
Since you cannot trust shore power connections you should carry one of the plug in testers to check for proper neutral and ground connections on shore power outlet before you plug in. Also a good idea if you get a neutral-ground outlet tester that also measures AC voltages, should include L1-N-L2 voltages if plugging into 240/120vac shore power.
You do not want a potential between your RV cabin and earth ground when someone grabs handle on RV when stepping up to RV entrance.
On inverter/chargers, their EMI filtering can cause problems tripping shore power GFCI breakers.
Since you cannot trust shore power connections you should carry one of the plug in testers to check for proper neutral and ground connections on shore power outlet before you plug in. Also a good idea if you get a neutral-ground outlet tester that also measures AC voltages, should include L1-N-L2 voltages if plugging into 240/120vac shore power.
You do not want a potential between your RV cabin and earth ground when someone grabs handle on RV when stepping up to RV entrance.
On inverter/chargers, their EMI filtering can cause problems tripping shore power GFCI breakers.
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Pappion
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That's a rarity that's been tried and failed. Just too sensitive for an entire RV. Older generation converters have enough leakage to trip it. Newer ones use optical isolators instead of resistors strings for internal communication.
In the home GFCI is used for wet area sockets the consumer has ready access too. They tried to require other locations, but got a lot of push back. ex. Socket under sink, for Dish Washer (phase 1) and Garbage Disposal (phase 2) on the same neutral, and Grounded.
RVs typically use 30A or 50A service. The Tenters and others use extension cords plugged into GFCI socket.
"All 125-volt, single-phase, 15- and 20-ampere receptacles at RV parks are required to have listed ground-fault circuit-interrupter (GFCI) protection for personnel. 30- and 50-ampere receptacles used in RV park supply equipment shall not be required to meet the requirements of 210.8(B)."
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RCinFLA
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EMI filtering is the common mode RF choke filtering on AC input and AC output of inverter. Nothing to do with opto-isolators.
The EMI filters typically have a couple of bypass capacitors in the 0.1 uF range either side of an inductor choke and capacitors must be connected to inverter metal case ground to reduce RF interference emissions from switching noise emissions from inverter. The capacitors create enough leakage current from AC input L line to inverter case ground to trip most GFCI breakers by leaking about 5 mA from AC L line to ground causing an upstream GFCI source breaker to detect L-N current imbalance.
As of 2020, 120vac and 240vac outside lines must have GFCI breakers to be NEC compliant. Any RV park's insurance company will likely insist on upgrades to include GFCI breakers.
This is not just outside receptacles like in RV park. It also includes outside appliances like air conditioner units and sprinkler pumps running on 240vac.
This has caused a lot of headaches for variable-speed inverter compressor air conditioner units which also have EMI filters in front of their three-phase compressor driver inverter. As of mid 2021, many states/counties have issued a temporary variance to Article 210.8 (F) of the National Electrical Code. This temporary variance only pertains to ductless mini-split units and high-efficiency units that use a variable frequency drive to control the operation of the outdoor compressor.
The EMI filters typically have a couple of bypass capacitors in the 0.1 uF range either side of an inductor choke and capacitors must be connected to inverter metal case ground to reduce RF interference emissions from switching noise emissions from inverter. The capacitors create enough leakage current from AC input L line to inverter case ground to trip most GFCI breakers by leaking about 5 mA from AC L line to ground causing an upstream GFCI source breaker to detect L-N current imbalance.
As of 2020, 120vac and 240vac outside lines must have GFCI breakers to be NEC compliant. Any RV park's insurance company will likely insist on upgrades to include GFCI breakers.
This is not just outside receptacles like in RV park. It also includes outside appliances like air conditioner units and sprinkler pumps running on 240vac.
This has caused a lot of headaches for variable-speed inverter compressor air conditioner units which also have EMI filters in front of their three-phase compressor driver inverter. As of mid 2021, many states/counties have issued a temporary variance to Article 210.8 (F) of the National Electrical Code. This temporary variance only pertains to ductless mini-split units and high-efficiency units that use a variable frequency drive to control the operation of the outdoor compressor.
Pappion
Retired Engineer Tech
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GFCI Protections Are Focus Of NEC Update
"In the 2020 code RV pedestals are explicitly excluded from the need for 30- and 50-amp GFCI protection for the following reasons:
— The 30- and 50-amp power on the RV pedestal are considered feeder circuits (those circuits that feed another panel) and not branch circuits. The changes made in 2017 applied to branch circuits, such as the 20-amp receptacle on an RV pedestal, not feeder circuits.
— The leakage current allowed by UL for GFCI circuits when all the downstream GFCI receptacles are added together would be enough to constantly trip the pedestal GFCI circuit."
https://www.rvtravel.com/30-and-50-amp-gfcis-in-campgrounds/
"I never said that, and here’s why. I have anecdotal evidence to back up my theory that total ground leakage currents in an RV shore power connection can easily total more than 5 mA. That’s because everything you plug into your RV leaks a little current to ground. That includes your microwave, stove, battery charger, inverters, air conditioner and control systems.
Most of these leakages are allowed by UL and the NEC, but each one could easily be 0.5 mA or so, with switching power supplies for your 12-volt converter having an exception to allow up to 3 mA of leakage (or thereabouts)."
https://wizard-of-watts.com/2020/03/15/the-revised-nec-551-71f-for-rv-parks/
https://www.jadelearning.com/blog/nec-rv-vehicles-and-parks-gfci-protection/
In Summary: ...The cumulative leakage could exceed the trip threshold of a Class A GFCI protection, resulting in nuisance tripping. A customary practice for curing this is clipping off the ground pin on the RV feeder cord, which could have disastrous results.
"In the 2020 code RV pedestals are explicitly excluded from the need for 30- and 50-amp GFCI protection for the following reasons:
— The 30- and 50-amp power on the RV pedestal are considered feeder circuits (those circuits that feed another panel) and not branch circuits. The changes made in 2017 applied to branch circuits, such as the 20-amp receptacle on an RV pedestal, not feeder circuits.
— The leakage current allowed by UL for GFCI circuits when all the downstream GFCI receptacles are added together would be enough to constantly trip the pedestal GFCI circuit."
https://www.rvtravel.com/30-and-50-amp-gfcis-in-campgrounds/
"I never said that, and here’s why. I have anecdotal evidence to back up my theory that total ground leakage currents in an RV shore power connection can easily total more than 5 mA. That’s because everything you plug into your RV leaks a little current to ground. That includes your microwave, stove, battery charger, inverters, air conditioner and control systems.
Most of these leakages are allowed by UL and the NEC, but each one could easily be 0.5 mA or so, with switching power supplies for your 12-volt converter having an exception to allow up to 3 mA of leakage (or thereabouts)."
https://wizard-of-watts.com/2020/03/15/the-revised-nec-551-71f-for-rv-parks/
https://www.jadelearning.com/blog/nec-rv-vehicles-and-parks-gfci-protection/
2020 NEC – Tentative Interim Agreement RV Vehicles & Parks, Section 551.71(F), GFCI Protection
The intent of this TIA is to clear up a potential conflict in the Code. Although the TIA has not been processed through the entire standards development process, it is enforceable code language. It is interim since it is effective only between editions of the Code. It is automatically considered for the next code cycle and will be subjected to all of the procedures of the standards development process. This is a good example of why it is important for both installers and inspectors to keep up with code changes that occur between cycles.In Summary: ...The cumulative leakage could exceed the trip threshold of a Class A GFCI protection, resulting in nuisance tripping. A customary practice for curing this is clipping off the ground pin on the RV feeder cord, which could have disastrous results.
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