Floating ground
Encyclopedia
A floating ground is a circuit's ground
that is not grounded, rather, it is just a common node in the circuit.
This can occur in 3 possible ways
When an electrical device is accidentally or intentionally grounded to its surround structural component (chassis), this is called a "live chassis." Circuit failures resulting in live chassis contrary to design plans can mean that anything (e.g. a person) that touches the device and is grounded on something with a different charge (e.g. terra firma) will now experience a voltage potential across its body. This can lead to death or harm by electrocution.
Intentional floating grounds formed by design are widespread in domestic electronic appliances. Providing the design is satisfactory they aren't a safety issue.
Ungrounded equipment designed to be grounded is a safety
issue. It leaves users unprotected against the risk
of shock due to a potential further fault
.
Exposed live grounds are dangerous. They are live, and can electrocute
end users if touched. Headphone sockets fitted by end users to live chassis TVs are especially dangerous, as not only are they often live, but the danger
is carried directly to the user's head
.
Floating grounds can cause problems with audio equipment using RCA/phono connectors. With these common and somewhat antiquated connectors, the signal pin connects before the ground, and 2 pieces of equipment can have more voltage difference between their grounds than it takes to saturate the audio input. As a result, plugging or unplugging while powered up can result in very loud noises in speakers. If the ground voltage difference is small, it tends to only cause hum & clicks.
Ground (electricity)
In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
that is not grounded, rather, it is just a common node in the circuit.
This can occur in 3 possible ways
- as the result of intentional design, and entirely harmless
- as the result of failureFailureFailure refers to the state or condition of not meeting a desirable or intended objective, and may be viewed as the opposite of success. Product failure ranges from failure to sell the product to fracture of the product, in the worst cases leading to personal injury, the province of forensic...
to ground equipment that was designed to require grounding - as the result of exposing a live ground that was intended to remain unexposed (live chassis TVs were common until the 1990s, where the set's ground is derived by rectifying live mains)
When an electrical device is accidentally or intentionally grounded to its surround structural component (chassis), this is called a "live chassis." Circuit failures resulting in live chassis contrary to design plans can mean that anything (e.g. a person) that touches the device and is grounded on something with a different charge (e.g. terra firma) will now experience a voltage potential across its body. This can lead to death or harm by electrocution.
Intentional floating grounds formed by design are widespread in domestic electronic appliances. Providing the design is satisfactory they aren't a safety issue.
Ungrounded equipment designed to be grounded is a safety
Safety
Safety is the state of being "safe" , the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be...
issue. It leaves users unprotected against the risk
Risk
Risk is the potential that a chosen action or activity will lead to a loss . The notion implies that a choice having an influence on the outcome exists . Potential losses themselves may also be called "risks"...
of shock due to a potential further fault
Fault
Fault may refer to:*Fault , planar rock fractures which show evidence of relative movement*Fault , in dog breeding, is an undesirable aspect of structure or appearance that indicates the dog should not be bred...
.
Exposed live grounds are dangerous. They are live, and can electrocute
Electrocution
Electrocution is a type of electric shock that, as determined by a stopped heart, can end life. Electrocution is frequently used to refer to any electric shock received but is technically incorrect; the choice of definition varies from dictionary to dictionary...
end users if touched. Headphone sockets fitted by end users to live chassis TVs are especially dangerous, as not only are they often live, but the danger
Danger
Danger may refer to:* Risk, the threat of adverse events* Danger , a Microsoft subsidiary which made cellular telephones* Danger , French electronic composer and performer* Danger , the fourth studio album by P-Square...
is carried directly to the user's head
Head
In anatomy, the head of an animal is the rostral part that usually comprises the brain, eyes, ears, nose and mouth . Some very simple animals may not have a head, but many bilaterally symmetric forms do....
.
- Sets that have both headphone socket and a live chassis use an audio isolation transformerIsolation transformerAn isolation transformer is a transformer used to transfer electrical power from a source of alternating current power to some equipment or device while isolating the powered device from the power source, usually for safety...
to make the arrangement safe.
Floating grounds can cause problems with audio equipment using RCA/phono connectors. With these common and somewhat antiquated connectors, the signal pin connects before the ground, and 2 pieces of equipment can have more voltage difference between their grounds than it takes to saturate the audio input. As a result, plugging or unplugging while powered up can result in very loud noises in speakers. If the ground voltage difference is small, it tends to only cause hum & clicks.