GFI/GFCI and RVs – OSI Mobile Technologies

GFI (Ground Fault Interrupter) or GFCI (Ground Fault Circuit Interrupter) breakers are commonplace today and are required on new or upgraded electrical circuits in many instances. The terms “GFI” and “GFCI” refer to the same class of device and the labels can be used interchangeably. The ground fault detection and circuit interrupter can be located in the service panel as a breaker or in an outlet, but for the discussion here they will be addressed as the GFI/GFCI “breaker”. They are found in every home and building and are required by electrical codes for kitchens, bathrooms, outside receptacles, and other potential wet areas. A ground fault breaker operates by detecting a small ground “fault” current to protect people from potential dangerous electrical shocks. However, there are issues when plugging a recreational vehicle into a GFI/GFCI protected breaker. I will attempt to explain the operation of GFI/GFCI breakers and the issues with RV operation below.

All ground fault interrupter breakers operate by detecting a small current imbalance in the hot-neutral path that is flowing in the ground wire of a protected circuit. Normally a circuit load is connected between the “hot” and “neutral” leads of an outlet. The ground, which is connected to earth ground potential, should not have any current flowing through it. All of the current is flowing through the hot and neutral wires to power the appliance. Now imagine the appliance being powered has a “fault” or short (or partial short) from the hot side of the circuit to the metal body of the appliance due to worn or faulty wiring inside the appliance. When a person touches the body of the “hot” appliance an electrical path is set up through his body to ground and he will receive a shock. The purpose of a GFI/GFCI breaker is to detect this small ground current by the imbalance of current that is normally flowing through the hot-neutral wiring and trip the breaker preventing a serious shock.

The specifications for GFI/GFCI breakers are set such that the breaker will trip before a serious life threatening shock is delivered to a human. For a class A breaker which is most commonly found in residential applications, the maximum ground leakage current is 6 mA with the breaker tripping in less than 30 mS if the threshold current level or greater is detected. Note that 1 mA is equal to 0.001 Amperes so 6 mA is 0.006 Amperes. This is a very small current compared to a typical space heater that draws around 12 Amperes. Likewise 30 mS is equal to 0.03 Seconds. An adult human can suffer a life threatening shock (upsetting heart rhythm) at around 30 mA so it can be seen that the breaker should trip well before any serious threat to a human is experienced.

So far it seems like ground fault breakers are a good idea to use everywhere, then why are they not used on all electrical circuits and why are they not a good idea for the RV main power pedestal circuit? Let’s explore the reasons in detail.

Appliance Leakage Currents

All appliances have a small amount of ground leakage current since there are no perfect insulators. In most appliances this is orders of magnitude smaller than the GFI trip current but leakages can increase due to age and other factors such as temperature and humidity. The industry specification limits for appliance ground leakage can vary from 0.25 mA for a hand-held unit to 3.5 mA for a stationary appliance. These are all below danger levels and trip levels of GFI breakers. For a residential setting there are usually only one or two appliances plugged into any particular circuit. For an RV there may be a dozen or more electrical appliances connected to the 120 VAC electrical system. All the ground leakages of these units are adding together and can exceed 6 mA total. Remember “appliances” include everything that is plugged into the RV’s outlets plus hardwired units such as the air conditioner, refrigerator and water heater.

RVs Have GFI Breakers Already

All modern recreational vehicles have GFI outlets and/or breakers installed in kitchens, bathrooms, and outside outlets similar to a residential house. Requiring an RV to plug into a GFI breaker is redundant since the breakers already installed in the RV will protect the occupants.

Radio Frequency Tripping

Many RV enthusiasts have 2-way radios installed in their rigs. If you are a ham radio operator you have more than likely experienced a GFI breaker tripping when you are transmitting. The reason is the radio frequency “RF” energy is picked up by the AC wiring and causes the the GFI breaker to detect a false current on the ground circuit. Newer model GFI breakers seem to have improved on this false tripping mode but it is still a problem on many units.

Nuisance Tripping

“Nuisance tripping” includes other spontaneous tripping of the GFI breaker sometimes for no obvious reason. It is especially an issue when power is lost for heating/air conditioning and refrigeration. This can be more than just an inconvenience when the RV is not occupied on a hot day and pets are in danger and food is spoiled in the refrigerator. There are technical reasons for nuisance tripping mostly related to high current transients such as an air conditioner compressor starting causing high ground fault transient currents. The additional details are beyond the scope of this article but I have been able to measure these type of transients with high speed analysis equipment. Another source of nuisance tripping for outdoor outlets is condensing high humidity (fog) which causes a film of water to conduct enough electricity resulting in a ground fault breaker trip.

GFI/GFCI Variations

Another factor I have observed during the development of the RV power monitor is that there are significant variations between brands of GFI/GFCI breakers. Considering the specification limits for tripping a breaker are 6 mA leakage and 30 mS maximum time, some brands are much more sensitive and faster. A tripping current of 4 mA is not unusual and some units will trip in 1 mS! Remember the nuisance tripping explanation above, a breaker that is very fast will be more likely to trip with a compressor starting transient than one that has a longer time detection.

Fortunately the normal configuration for most campground power pedestals today is a 30 Amp outlet and/or a 50 Amp outlet without GFI/GFCI and a 15 or 20 amp convenience outlet with GFI/GFCI protection. The National Electric Code considers the 30/50 Amp outlets as “power supply” circuits that do not require GFI protection. The 15/20 Amp outlet is intended to be used as a convenience outlet to plug in lights, fan, a hot plate, or other small appliances and is GFI protected similar to a protected outdoor outlet found on a permanent residence.

A major issue is when RV users plug into a 15/20 Amp GFI circuit for battery charging or to operate a few appliances such as a refrigerator. Many owners plug their RV into a regular 15/20 Amp service outlet at a storage lot or into an outdoor outlet at home to keep the batteries charged when storing the RV. It doesn’t take much searching on RV forums to see people complaining about GFI outlets/breakers constantly tripping and experiencing dead house batteries or room temperature refrigerators. The reasons cited previously, even with a light electrical load, are causes for the constant tripping. If you are fortunate enough to have RV storage space at your house, then consider installing a separate 30 or 50 Amp circuit with a dedicated outlet to power your RV while in storage. It will save you a lot of headaches and is worth the cost in the long run.

It is worth mentioning that some municipalities and areas of the country are requiring GFI breakers on 30 and 50 Amp circuits. Electrical codes can vary greatly from area-to-area (also see the neutral-ground bonding discussions) and there are reports from fellow RV enthusiasts that at least one state has state parks with GFI outlets on all power pedestal plug positions. Fortunately there does not seem to be a universal push to convert 30/50 Amp RV parks over to GFI breakers. If you do end up at a park with all GFI breakers be aware of the issues discussed above.

The OSI Power Monitor has been designed to be compatible with GFI/GFCI breakers. This is also in recognition that many owners need to plug their RVs into 15/20 Amp convenience outlets during storage and want the continued protection of the power monitor. However, it is impossible to test all current and past models of GFI/GFCI breakers for compatibility. If the GFI breaker trips when plugging the RV in, even without a power monitor, try to reset the breaker after the plug is inserted (it is always good practice if accessible to turn the main breaker off at the power pedestal before inserting the plug to prevent arcing). The best solution is to install a dedicated non-GFI circuit if allowed for powering the RV that is in compliance with local electrical codes.