Is 'ground' any metal thing that's not a wire, or it is really GROUND as-in EARTH? Is there a difference and why should we care?
There are at least two VERY good reasons to implement proper (National Electrical Code and local code required) grounding of your RV, by the site-provided power pedestal or when using a portable generator:
Admittedly electrical systems, wires, generators, connections can be very tricky, confusing and almost contradictory at times.
Professionals and technical 'enthusiasts' alike can relate to experiencing and being challenged by some of the most obscure and bizarre aspects of electricity.
While in many ways "all electricity is the same", in just as many ways it is not. Our vehicle and RV 12 volt battery and solar systems and devices behave much differently than our home and RV 120 volt AC systems. Obviously one is lower voltage and the other is dangerously higher, but AC provides some interesting characteristics that make it less obvious as a safety concern.
AC and DC power may be used for same or similar purposes - to light or do work - depending on how the device is designed. However, one type of power may be better-suited to some devices and types of work than the other.
D.C., Direct Current, circuits require and operate with *direct* physical connections only. A.C., Alternating Current, circuits can work with both direct connections (wires, connectors, switches, bulbs...) as well as indirectly coupled connections (typically transformers, or inductive/'radiated' coupling, much like how radio waves travel through the atmosphere.
Because AC-power is implemented and functions much differently, typically at much higher energy levels than DC-power, at least that it can traverse or be imposed on other objects even without direct contact, it is a more significant safety concern.
While there are many general rules and practices for handling DC-power, there are many more specific rules, practices and even laws concerning AC-power.
We can list, and there are many, covering the laws, the rules, the methods, but the how and why electrical safety is a concern, how to properly implement it to protect against known and possible risks is less obvious.
There are a few ways to represent how insidious, tricky, and unpredictable AC-power risks come about without going in-depth with electrical theory, absolute measurements and complex circuits. I don't want to leave the impression that AC-power is magical, mystical - that its behavior and control of it is only for the elite or special 'wizards' - but sometimes analogies and visualization can make it more relevant to a general audience that simply wants to enjoy safe RV-ing.
As a wave it is more commonly associated with, taken advantage of through its property of being electro-magnetic waves. It can 'travel', move, be directed and transported through a variety of electrical components and transfer systems, and can be used very efficiently to make other things move - like fans and pumps.
AC-power is most often created by a rotating source - a generator - driven by water, steam or fuel-driven engine. This is a very efficient way of generating the 'wave'. Being an electro-magnetic wave the power can be efficiently transported over pairs of wires, through transformers that can increase or decrease the potential energy to levels usable by many items.
Commercially, on the domestic power grid - AC-power starts out and is transported at very high potential - 100,000 volts. When the power is transported to points of consumption, it is reduced in potential to make it safer and more manageable for connection to businesses, homes and our devices.
At our homes power arrives at 220-240 volts through two opposite circuits of 110-120 volts. The 220-240 volt connection is more efficient for large appliances - ovens, electric dryers and air conditioners. The 110-120 volt connections are more appropriate for lighting and small appliances and electronics.
Internal to most electronic devices the 110-120 volts is further reduced, regulated and even converted to DC power necessary for electronic circuits (computer chips and amplifiers) to function.
The fact that AC-power is an electro-magnetic wave that can surround, emit (radiate) from and be coupled or transferred to and through metal/conductive objects is the very reason it is also a potential safety hazard if and when coupled to devices we do not want to be so energized - other wires, generator frames, the chassis of our RVs. This is specifically where the grounding concern comes into play.
Earth-grounding the enclosures can also keep the electro-magnetic wave from transferring energy to other objects. Without this containment and virtual shorting out or blocking of the wave to Earth-ground, the electrical pipes (conduit) and connection boxes could become 'hot' circuits causing injury, death or possibly fire.
Again - it is this electro-magnetic property of AC power that makes it efficient to generate, transport and use, but also challenging to provide reliable safety measures for. The higher voltage is also a significant concern. It is much easier to encounter a shock or injury hazard from this higher 120 or 240 volts than from a lower 12 volt circuit.
Because of soil resistance and relatively poor/non-intimate contact with only the surface, as well as debris (foliage, twigs, rocks) simply setting a generator and lowering your jack stand and stabilizers onto the ground does not 'ground' it. The generator frame is likely painted, has 'feet' or pads, and the loose mechanical connections of jack and stabilizer parts make VERY poor if any electrical connection.
The result is that your 120 or 120/240 volt generating system and your RV are floating above (Earth) ground potential. Some of the wave energy from the generator itself could be imposed onto the frame, as an electro-magnetic wave could interact with and create a potential difference between the Earth and the frame - and this is that safety hazard - your portable electrical system is now "an electrified fence" from the perspective of your feet on the Earth along your body to wherever you touch the generator or RV. The amount of potential difference, the voltage between Earth and the frame/chassis can also vary by how much electrical load is in use.
Still another simpler risk in general would be that of a short (partial or total) in the generator electrical system that could place hot 120 V directly to the frame. Power-wise you might not ever know this happened - A/C and microwave still work, battery charges - but your entire RV could be sitting at 120 V. Step out onto your grassy wilderness patio while in contact with the door or hand-rail and experience a very nasty surprise.
Without establishing a very deliberate, direct, physical connection and ultimately protection circuit between the generator frame and your RV chassis to the Earth, you risk at least a mild tingle if not up to a lethal shock.
The relative inconvenience of setting out a few feet of wire and a "tent stake" can be invaluable protection. You, your family, your pets, and your RV systems deserve as close to utility-grade safety as possible.
Aside from injury or equipment damage there are not so subtle consequences should you have to file an insurance claim for medical expenses, property losses or other liabilities that could be denied for not complying with any applicable local standards or insurance requirements.
Proper safety practices are not just a suggestion, a little known requirement, they can be essential!
Cut the wire into two pieces - one long enough to parallel the length of your power cord, to go from the generator to the ground stake, the other long enough to go from the trailer 'stud' to the stake. Attach the wire lugs at each end.
Set the ground stake near the trailer to avoid being a surprise trip/ankle hazard. Run out your power cord and generator ground wire. Secure the ground wires first, then connect the power cord. DONE.
Please do NOT scrimp and think to only ground the generator or only ground the RV chassis. If you think to rely on the power cord's 'ground' wire and only ground the generator you have a potential point of failure and the trailer could not be grounded. If you think to rely on the power cord's ground wire and only ground the trailer the generator could be left unprotected. GROUND BOTH!
Keep this grounding wire kit with your electrical cord or generator stash and you're good, and safe, to go!
Brief NEC References to RV Power
OSHA Reference to Generators
Good Sam Reference to Generator Grounding
Simplified Diagram of Implementing Generator and RV Grounding (PDF file)
Downloadable PDF version of this page
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