ANY shock is dangerous and there is really no such thing as a little shock being okay. Many of the yearly electrocutions in the United States are from known “little shock” situations that became deadly. Virtually EVERYTHING metal in your RV is tied to the chassis at the factory. It only takes about 20mA of electrical current (20/1000) of an amp) to cause your body to clamp down and not be able to let go of an energized wire and 30 mA of current (30/1000 of an amp) for a few seconds can cause your heart to go into fibrillation.
By itself, an open ground connection will not cause a RV hot-skin voltage condition, but nearly anything inside your RV plugged into its electrical system will cause some leakage current to the RV chassis-ground. That leakage will show up as a hot-skin voltage of varying degree. The dangerous thing is that sometimes those can be high-impedance leakage currents that are not particularly dangerous and that is when you feel a “little” shock. However, that same “little” current can quickly become low-impedance/high-current leakage in a heartbeat, and that will almost certainly kill you if you touch the RV with wet hands and feet. It is just a matter of degree, and you never know what that degree is. So, any feeling of shocks from your RV or appliance is a warning to turn off the circuit breakers and disconnect the power plug immediately.
So, what can be a cause of Hot Skin? ( a serious problem with your safety ground; a broken or loose ground contact on your extension cord or dog-bone adapter; a problem in your worn campsite pedestal or home power outlet; corroded or loose contacts; mis-wiring condition of reverse polarity; a screw through your wiring, and more)
Current (I), describes the amount of energy (volume of electrons) flowing down a potential gradient and is measured in amperes (A). This describes the amount of energy that flows through the affected individual’s body as a result of an electrical injury. Individuals vary in the amount of maximum current they can tolerate touching while still being able to let go of the electrical source before induction of muscle tetany.
Resistance (R) is a measure of how a material reduces the amount of electrical flow that passes through it, measured in ohms. In the body, resistance varies between tissues, depending on the level of water and electrolytes that are present. The highest concentration of electrolytes and water (and therefore the lowest resistance) are found in blood vessels, neurons, and muscles. For this reason, these are excellent conductors of electricity in the body.
Tissues with the highest resistance tend to suffer the greatest level of damage because of an electrical injury. High skin resistance will cause a larger amount of energy dissipation at the level of the skin resulting in skin burns, thereby reducing the level of resultant internal damage. On the other hand, low skin resistance may result in less obvious skin injury or no skin injury at all, while a larger amount of electrical energy is transferred to internal tissues. For this reason, the extent of external burns on the skin does not predict the level of damage that will be found internally, nor does total absence of external burns predict the total absence of internal electrical injury.
Other determinants of electrical injury throughout the body are the source (i.e., entry point) and ground (i.e., exit point) of the current. The most common source is a hand, followed by the head, while the most common ground is usually a foot. Any current passing through the head may result in central nervous system (CNS) damage. The heart is most often affected if the current travels from hand to leg or hand to hand across the body, and this may result in a potentially fatal arrhythmia.
Ohm’s law describes the relationship between current, voltage, and resistance, such that voltage is directly proportional to current, while indirectly proportional to resistance. The degree of electrical injury experienced by an individual can be predicted by Kouwenhoven factors include the type of current, current strength, length of time of exposure, body resistance, and the pathway the current takes in the body in addition to electrical field strength.
Type of current refers to either alternating current (AC) or direct current (DC). AC, the current found in household electrical outlets (generally 50 Hz to 60 Hz; low frequency), changes direction rhythmically, while DC, the current found in most batteries, constantly flows in one direction. Most cardioverters and defibrillators also use DC. The higher the current and voltage associated with AC or DC, the greater the electrical damage will be.
Muscle tetany (intermittent muscular spasms) typically occurs in response to electrical stimulation and if this muscle contraction occurs in the hand, contraction of flexors will cause the affected individual to grasp the source and prolong contact with the electrical source. Most humans can perceive electrical energy, to touch, at a current of 1 milliamp (mA). Let-go current refers to the amount current (amperage) that will still allow an individual to release the source, even though muscle contraction is induced. The amount of amperage tolerated per individual (let-go current) varies depending on his or her size (i.e., muscle mass and weight).
Electrical field strength must be considered when determining the level of tissue injury. Field strength is determined based on the amount of voltage that is encountered, in addition to the size of the area with which it comes in contact. For example, a very high voltage that encounters a larger surface area may have a field strength that is equal to or perhaps even less than a much smaller voltage encountering a much smaller surface area. For this reason, low-voltage injuries (spread out over a smaller area) can often result in the same amount of damage as high-voltage injuries (spread out over a larger area).
Potential long-term sequelae of electrical injuries may include neurological (e.g., neuropathy, seizures, syncope, tinnitus, paresthesia, weakness, loss of balance, poor coordination, or gait ataxia), psychological (e.g., memory or attention difficulties, irritability, depression or post-traumatic stress), ocular (e.g., cataracts) or physical (e.g., pain, fatigue, contractures, muscle spasms, pruritus, headaches, fever or night sweats, and reduced range of motion or stiffness in the joints) disturbances.
That SHOCK is a warning, don’t expose your family, friends, pets to a potentially injurious or deadly situation. Find and fix the electrical problem causing the supposedly “little shock”.
For more electrical information please refer to http://noshockzone.org/. http://www.elcosh.org/document/1624/888/d000543/section2.html