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 > Will GFCI work with items without equipment ground

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Hurricaner

Hurricane Utah

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Posted: 08/21/19 09:06am Link  |  Quote  |  Print  |  Notify Moderator

mikestock wrote:

All this brings up another related topic. I know I'm wavering.

My RV is in a storage lot where a, low potential, outlet is supplied for each camper. An AC unit or electric water heater will immediately trip the main.

We, pretty much, only plug up to keep batteries charged. Nobody loads anything of consequence on the inverter or 12 volt system.

Every motorhome owner I talk with seems to have a persistent problem with the GFCI's tripping. The only thing we all have in common is that we all have an inverter. Mine is a 1500 watt Xantrex PSW.

Is there something inherent with motorhomes that could cause this? I know the 15 amp connections an campgrounds are GFCI, but I doubt they are used by motorhomes.


Read ktmrfs post above (very good post) and note the last paragraph. If the inverter has the neutral/ ground bonded and its transfer switch defaults to the inverter, before the switch can transfer the gfi will pick up a neutral to ground fault and trips. This use to be a problem years ago but I thought the inverter manufactures had solved it, but maybe not. It could also be the inverters were not installed properly.

Sam


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ktmrfs

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Posted: 08/21/19 09:06am Link  |  Quote  |  Print  |  Notify Moderator

mikestock wrote:

All this brings up another related topic. I know I'm wavering.

My RV is in a storage lot where a, low potential, outlet is supplied for each camper. An AC unit or electric water heater will immediately trip the main.

We, pretty much, only plug up to keep batteries charged. Nobody loads anything of consequence on the inverter or 12 volt system.

Every motorhome owner I talk with seems to have a persistent problem with the GFCI's tripping. The only thing we all have in common is that we all have an inverter. Mine is a 1500 watt Xantrex PSW.

Is there something inherent with motorhomes that could cause this? I know the 15 amp connections an campgrounds are GFCI, but I doubt they are used by motorhomes.


if the trailer/motorhome has an outside outlet (which virtually all do) in wet weather moisture can build up in that outlet and cause enough leakage current to trip an upstream GFCI outlet. be it the breaker with GFCI or the trailer GFCI.


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ktmrfs

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Posted: 08/21/19 09:09am Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

Will it work: Perfectly
Does the GFCI care. On some of 'em the safety ground is not even connected.

the ground lug better be connected on a GFCI outlet or it is a code violation. And GFCI outlets sold today detect ground/neutral bonding so they must have a connection to the downstream ground.

DrewE

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Posted: 08/21/19 09:40am Link  |  Quote  |  Print  |  Notify Moderator

ktmrfs wrote:

wa8yxm wrote:

Will it work: Perfectly
Does the GFCI care. On some of 'em the safety ground is not even connected.

the ground lug better be connected on a GFCI outlet or it is a code violation. And GFCI outlets sold today detect ground/neutral bonding so they must have a connection to the downstream ground.


If you have a safety ground conductor available, indeed it must be connected properly, both per the electric code and per common sense.

If you have an old electric system which lacks a safety ground, it is permissible by code to install a GFCI and so be able to plug in three prong cords (for grounded devices) without rewiring everything. Such an outlet must be labeled as not having an actual safety ground. Absent the GFCI, only ungrounded (two prong) outlets would be permitted to be installed.

Current GFCIs do detect ground/neutral shorts upstream and trip if they are found. I don't believe any of them require that ground and neutral be bonded downstream, but perhaps I am misinformed on that. It's not a universal requirement at any rate.





Harvard

51.6N 114.7W

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Posted: 08/21/19 09:53am Link  |  Quote  |  Print  |  Notify Moderator

mikestock wrote:

All this brings up another related topic. I know I'm wavering.

My RV is in a storage lot where a, low potential, outlet is supplied for each camper. An AC unit or electric water heater will immediately trip the main.

We, pretty much, only plug up to keep batteries charged. Nobody loads anything of consequence on the inverter or 12 volt system.

Every motorhome owner I talk with seems to have a persistent problem with the GFCI's tripping. The only thing we all have in common is that we all have an inverter. Mine is a 1500 watt Xantrex PSW.

Is there something inherent with motorhomes that could cause this? I know the 15 amp connections an campgrounds are GFCI, but I doubt they are used by motorhomes.


Can you imagine having your whole house protected by one 5 mA GFCI.
Why do we think a single 5mA GFCI is going to cope with an entire RV sub system. Just saying.

Sam Spade

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Posted: 08/21/19 11:09am Link  |  Quote  |  Print  |  Notify Moderator

Harvard wrote:


Can you imagine having your whole house protected by one 5 mA GFCI.
Why do we think a single 5mA GFCI is going to cope with an entire RV sub system. Just saying.


Because it WILL.

It is common practice to use a single GFI in buildings to feed/protect multiple outlets, even in different rooms, sometimes on different sides of the house.

I absolutely HATE having it wired that way.
It is a royal pain to have to search out the tripped GFI when it is in the other end of the house......or in the garage.


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time2roll

Southern California

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Posted: 08/21/19 11:15am Link  |  Quote  |  Print  |  Notify Moderator

mikestock wrote:

All this brings up another related topic. I know I'm wavering.

My RV is in a storage lot where a, low potential, outlet is supplied for each camper. An AC unit or electric water heater will immediately trip the main.

We, pretty much, only plug up to keep batteries charged. Nobody loads anything of consequence on the inverter or 12 volt system.

Every motorhome owner I talk with seems to have a persistent problem with the GFCI's tripping. The only thing we all have in common is that we all have an inverter. Mine is a 1500 watt Xantrex PSW.

Is there something inherent with motorhomes that could cause this? I know the 15 amp connections an campgrounds are GFCI, but I doubt they are used by motorhomes.
You can isolate the circuits and discover the offending issue. Or consider using a portable battery charger instead of the converter with entire RV system connected. A 5 amp rated charger should be plenty.


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Harvard

51.6N 114.7W

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Posted: 08/21/19 11:25am Link  |  Quote  |  Print  |  Notify Moderator

The under lying issue with "unexpected" GFCI tripping from an RV sub system is called "stray capacitance" which allows for stray current leakage. Every foot of wire has some stray capacitance and some loads have RFI capacitors across their AC input circuits. All this "Normal Capacitance" soon adds up to be a 5 mA current leakage.

Dutch_12078

Winters south, summers north

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Posted: 08/21/19 11:25am Link  |  Quote  |  Print  |  Notify Moderator

Harvard wrote:

mikestock wrote:

All this brings up another related topic. I know I'm wavering.

My RV is in a storage lot where a, low potential, outlet is supplied for each camper. An AC unit or electric water heater will immediately trip the main.

We, pretty much, only plug up to keep batteries charged. Nobody loads anything of consequence on the inverter or 12 volt system.

Every motorhome owner I talk with seems to have a persistent problem with the GFCI's tripping. The only thing we all have in common is that we all have an inverter. Mine is a 1500 watt Xantrex PSW.

Is there something inherent with motorhomes that could cause this? I know the 15 amp connections an campgrounds are GFCI, but I doubt they are used by motorhomes.


Can you imagine having your whole house protected by one 5 mA GFCI.
Why do we think a single 5mA GFCI is going to cope with an entire RV sub system. Just saying.


5mA is the leakage trip point, not the load trip point. As long as GFCI circuitry is built heavy enough to carry the intended load, it will work. For example, a 50 amp 2-pole GFCI breaker would handle a 50 amp RV at normal loading, yet still trip with a 5mA+ leakage.


Dutch
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DrewE

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Posted: 08/21/19 01:47pm Link  |  Quote  |  Print  |  Notify Moderator

Harvard wrote:

The under lying issue with "unexpected" GFCI tripping from an RV sub system is called "stray capacitance" which allows for stray current leakage. Every foot of wire has some stray capacitance and some loads have RFI capacitors across their AC input circuits. All this "Normal Capacitance" soon adds up to be a 5 mA current leakage.


That is assuming you don't have a neutral/ground fault somewhere in the RV wiring, or a bad water heater element, or a bad fridge element, or water intrusion in some electrical box, or some other problem.

It takes hundreds of feet of Romex to get sufficient capacitive coupling in the cable to be problematic, somewhere around a few thousand feet I think. The current requirements for electronic devices are no more than 0.5 mA leakage in RFI filters, etc. A properly constructed RV, one with no ground faults, generally should not cause a good quality, properly functioning GFCI to trip. I suspect, albeit without proof, that more than a few RVers have actual electrical problems or faulty appliances that go uncorrected because they chalk things up to "RVs and GFCIs don't work well together" rather than looking to see if there really is a problem to be fixed.

(I'm also a little surprised the NEC doesn't require GFCI protection for outdoor RV receptacles as they do for standard outdoor receptacles.)

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