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"ground lift switch" question
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A Ground-lift switch will only remove the audio ground from safety ground it will NOT, ABSOLUTELY NOT remove the safety ground. Usually, this is done by switching in a resistor of value around 100-1000 ohms (also sometimes bypassed by a low value capacitor) between the audio ground and safety ground.
Cheater plugs as I understand them do remove the safety ground, and so must NEVER EVER be used in a permanent installation.
S.
Cheater plugs as I understand them do remove the safety ground, and so must NEVER EVER be used in a permanent installation.
S.
1. sergeauckland explained it right. Noise reduction depends on all other equipment and cabling. So it may or may not help to reduce noise/hum.
2. Don't know. Depends on the internal circuit and construction as well as safety aspects. Ask Topping.
2. Don't know. Depends on the internal circuit and construction as well as safety aspects. Ask Topping.
I can't find the exact resource now (it included pretty clear graphs laying out all reasons this is in fact an issue, or at least more than 'a tenny bit of a problem') but it might be one of the references found at the bottom of https://www.jensen-transformers.com/wp-content/uploads/2014/08/an004.pdf . To quote Bill Whitlock, whos word I'd rather take on this subject:
Electrocutions have happened because of cheater plugs. YMMV.
If you had ever had a real problem with equipment that you used the cheater plugs on, you might not be here to tell us about it.
solderdude
Grand Contributor
Only when one of the devices developped a fault where mains becomes connected with the chassis and all the not double insulated devices are not connected to safety ground.
This could happen when for instance all devices are connected to an extension/distribution cord that is connected to mains using such a completely silly 'cheater' plug, a failed safety ground on that distribution block or a disconnected ground wire in the mains wall outlet.
It still requires at least one of the devices to fail in a specific way though for it to become lethal.
What might happen is leakage current (through Y-caps) is adding up and becomes 'feel-able'.
This can be checked by rubbing one's finger across a metal chassis. When one feels a 'tingle' or 'vibration' in the finger it might be time to connect one or all 3-prong gear to safety ground.
3-prong devices SHOULD be connected to safety ground.
If using such a cheater plug solves a ground-loop issue then look for ways to get rid of that loop without using the cheater plug. Only use the cheater plug for trouble shooting not as a permanent solution.
This could happen when for instance all devices are connected to an extension/distribution cord that is connected to mains using such a completely silly 'cheater' plug, a failed safety ground on that distribution block or a disconnected ground wire in the mains wall outlet.
It still requires at least one of the devices to fail in a specific way though for it to become lethal.
What might happen is leakage current (through Y-caps) is adding up and becomes 'feel-able'.
This can be checked by rubbing one's finger across a metal chassis. When one feels a 'tingle' or 'vibration' in the finger it might be time to connect one or all 3-prong gear to safety ground.
3-prong devices SHOULD be connected to safety ground.
If using such a cheater plug solves a ground-loop issue then look for ways to get rid of that loop without using the cheater plug. Only use the cheater plug for trouble shooting not as a permanent solution.
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antcollinet
Grand Contributor
If the cheater plug is disconnecting the safety ground from your class 1 equipment you are creating a serious safety hazard. An internal fault could result in the chassis being live. There is also a fire risk as interconnect not rated for it tries to carry the fault current to a connected earthed device.
It is an unlikely thing to happen, but one that if it does has potentially fatal consequences.
Don't do it. It's not worth it.
Human Bass
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This switch only matters if you are using rca.
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My father was an electrical engineer. He was an expert contributor to some reviews of lethal electrocution. If a device has a safety earth pin it should never be bypassed except for a quick test by someone who knows what they are doing. If it fixes a ground loop, the loop should be analysed and fixed at audio-voltage levels, not mains-level voltages.
If there is a ground loop, by definition there are multiple points of the system being grounded. Lifting one will still keep the device connected to the ground through the others.
And honestly, how many devices have we heard that disconnected the line and touched the chassis? In 20+ years of audiophile hobby I never met someone who had this.
And honestly, how many devices have we heard that disconnected the line and touched the chassis? In 20+ years of audiophile hobby I never met someone who had this.
Not necessarily. If grounding is done through the audio cables, what happens if the cables are disconnected, or one is using daft cables grounded at one end only? Audio cables should never ever be expected to carry safety earths.
I heartily dislike equipment that only has a two core mains cable. In my view, if the case is made of metal, it should be grounded, and the audio ground properly dealt with.
S
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You guys would not have enjoyed living in the era of AC-DC transformerless, (vacuum tube heater) series-string "killer" radio, phonograph, and TV chassis!
They were extremely common at least in the US, from at least the 1940s (the ubiquitous "All American Five" superheterodyne AM radio variants) well into the 1960s.
At least in the US, before polarized (two prong) mains connections, there was a 50-50 chance that the chassis would be hot.
We'd usually test by feeling for that ineffable little tingle on the chassis with the plug inserted in either orientation.
Ahh, those were the days.
Look carefully at the very sophisticated power supply design of the spud amp (one tuber -- per channel, in this case) phonograph amplifier above.
source: https://www.worldradiohistory.com/B...ooks/RCA-Receiving-Tube-Manual-1964-RC-23.pdf (pg. 590)
Wet, bare feet on a concrete slab basement floor and an AA5 radio makes Russian Roulette look like a pretty good risk.
They were extremely common at least in the US, from at least the 1940s (the ubiquitous "All American Five" superheterodyne AM radio variants) well into the 1960s.
At least in the US, before polarized (two prong) mains connections, there was a 50-50 chance that the chassis would be hot.
We'd usually test by feeling for that ineffable little tingle on the chassis with the plug inserted in either orientation.
Ahh, those were the days.
Look carefully at the very sophisticated power supply design of the spud amp (one tuber -- per channel, in this case) phonograph amplifier above.
source: https://www.worldradiohistory.com/B...ooks/RCA-Receiving-Tube-Manual-1964-RC-23.pdf (pg. 590)
Wet, bare feet on a concrete slab basement floor and an AA5 radio makes Russian Roulette look like a pretty good risk.
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While they are not supposed to, if there is a ground loop present, then audio cables are transmitting current by definition. As long as the system is assembled, that is, devices are interconnected and working and the owner is not going to be moving or disconnecting them, then they are still grounded.
I have my amps ungrounded (ground disconnected from the receptacle) for some 15+ years by now, and sources grounded.
antcollinet
Grand Contributor
(EDIT - in discussion below feel free to replace "Fuse" with "Circuit breaker" depending on typically used protection devices in your region)
As I point out above relying on interconnect to earth your device is not safe: the ground connection (normally the shield) is not rated for the fault current.
Depending on the construction, the interconnect may cunningly protect the fuse by self immolating - in which case the chassis remains live. In the worst case they may self immolate in a way that if the live case doesn't get you, the roaring inferno might.
You may also have problems with your insurance in the case of a claim.
How many devices do you know of that have blown the fuse? Any one of those may have been unsafe if there was no fault current to blow it. I'll refrain from the gallows humour of stating that you've not met them because they are no longer around to meet.
. Oh.... wait... no I didn't (I can remember at least on person here reporting their device was repeatedly blowing a fuse. They were told in no uncertain terms to get it fixed or thrown away. Our toaster recently developed a fault which caused it to trip the breaker. After the third attempt it got trashed without a second thought.
Plus - why do you think the regs around class I or II equipment exist in the first place. Yes, it was because people got killed and injured before the regs were put in place.
See also stats on electrocutions, and electrical fires:
In general, there are 11 fatalities and 321 injuries attributed to electrical fires annually. Furthermore, 15 fatalities and 397 injuries result from faulty appliances in domestic properties (Electrical Safety First). To ensure electrical safety, purchase certified products from reliable sellers.
2024 Electrical Safety Statistics: Unveiling the Shocking Truth
Ensure electrical safety at work and home with essential tips and statistics from Meteor Electrical. Stay informed and protect your loved ones.www.meteorelectrical.com
And that is when almost all kit is hopefully complying to safety regs. The risk goes up significantly when you circumvent those.
And even if the risk is still low - the consequences are potentially infinte for the person hurt. Do you really want to gamble with your life and health - or that of your family and friends - even on long odds?
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LOL
As an offshoot of my audio hobby, I work on vintage audio equipment going back to the 1940s. Live chassis equipment was very common then, in part to save money, and in part because some parts of the UK still had DC mains then, so manufacturers were keen not to exclude potential customers, or risk the problems of someone putting a transformer on DC mains.You guys would not have enjoyed living in the era of AC-DC transformerless, (vacuum tube heater) series-string "killer" radio, phonograph, and TV chassis!
They were extremely common at least in the US, from at least the 1940s (the ubiquitous "All American Five" superheterodyne AM radio variants) well into the 1960s.
At least in the US, before polarized (two prong) mains connections, there was a 50-50 chance that the chassis would be hot.
We'd usually test by feeling for that ineffable little tingle on the chassis with the plug inserted in either orientation.
Ahh, those were the days.
Look carefully at the very sophisticated power supply design of the spud amp (one tuber -- per channel, in this case) phonograph amplifier above.
source: https://www.worldradiohistory.com/B...ooks/RCA-Receiving-Tube-Manual-1964-RC-23.pdf (pg. 590)
Wet, bare feet on a concrete slab basement floor and an AA5 radio makes Russian Roulette look like a pretty good risk.
I'm always VERY careful when working on this stuff, always use an isolating transformer, and keep my wits about me. Theoretically, users should never be able to make contact with a live chassis, but isolation of things like external antenna sockets or audio inputs relied on a single (now 70 years old) capacitor!
S
Some 35 years ago I debugged a device with high voltage inside using a scope. To measure a voltage difference at high level I disconnected the safety ground of the scope and told myself to be careful. A few minutes later while working the knobs of the scope my hand got in contact with one of the BNC connectors and I got a shock.
It's embarrassing for me to tell this but others need to learn from my foolish mistake.
It's embarrassing for me to tell this but others need to learn from my foolish mistake.
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