How dangerous is lifting the ground on a source component?

[DonH56]

Of course I know something is wrong.

My unstated question should have been, what can be done to safely eliminate hum when it’s associated with AC ground pin connections? What’s the cause and what’s the cure? This stuff is all supposed to work correctly together as provided, but it doesn’t. Am I expected to install isolation transformers at every connection? I just want to know where the fault is and how to fix it. And of course some of the components have no ground pin, including a new Sony 4K TV.

1. Try an RCA ground isolator (try on different components to see what works), e.g. https://smile.amazon.com/InstallGea...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
2. Try a cable isolator (cable is notorious for introducing ground loops), e.g. https://smile.amazon.com/Ground-Loo...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=
3. Try an AC (power line) isolator, e.g. https://smile.amazon.com/Ebtech-Hum...X&qid=1654439417&sprefix=hum-x,aps,107&sr=8-4

There are many examples of each, just grabbed what came up in a quick Amazon search. I would start with an RCA and cable isolator and see if those work first. Put the cable isolator in line nad see if that fixes it. If not, you can leave it, and try the RCA isolator on different components. You may want to start by pulling components one at a time (including the cable or cable box) to see if one of them makes the hum go away, then you can isolate just that component.

HTH - Don

 

[BDWoody]

Of course I know something is wrong.

My unstated question should have been, what can be done to safely eliminate hum when it’s associated with AC ground pin connections? What’s the cause and what’s the cure? This stuff is all supposed to work correctly together as provided, but it doesn’t. Am I expected to install isolation transformers at every connection? I just want to know where the fault is and how to fix it. And of course some of the components have no ground pin, including a new Sony 4K TV.

Are you connected to a cable or satellite system? Have you tried disconnecting the threaded coax from the system to see if that's the issue?

I've found cable issues to be at the heart of a few of my problems.

 

[DonH56]

Are you connected to a cable or satellite system? Have you tried disconnecting the threaded coax from the system to see if that's the issue?

I've found cable issues to be at the heart of a few of my problems.

Me too, and I am not talking about the wire...

 

[DavidMcRoy]

1. Try an RCA ground isolator (try on different components to see what works), e.g. https://smile.amazon.com/InstallGear-Ground-Isolator-Noise-Filter/dp/B077Y5DLBB/ref=sr_1_1_sspa?crid=1RB3JV8990DT4&keywords=rca+ground+loop+isolator&qid=1654439534&sprefix=rca+,aps,123&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFTNTA2TVZWR0k1V0EmZW5jcnlwdGVkSWQ9QTA5NjE5NTAyWk5RTzYxQU01UkNDJmVuY3J5cHRlZEFkSWQ9QTAwOTI4NTMxWU9HRllTVUk1TDdUJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
2. Try a cable isolator (cable is notorious for introducing ground loops), e.g. https://smile.amazon.com/Ground-Loop-Isolator-Transformer-Eliminator/dp/B08FRGH4X2/ref=sr_1_1_sspa?crid=1QZDI9VXST4UA&keywords=cable+ground+loop+isolator&qid=1654439497&sprefix=cable+ground,aps,111&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzME1HMTNFVFhCWEZYJmVuY3J5cHRlZElkPUEwODU3MTQ2MlJBR1pONDlJNlkxRSZlbmNyeXB0ZWRBZElkPUEwNzM4NzI4MTU3U1NPUFBNV1ZXRiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=
3. Try an AC (power line) isolator, e.g. https://smile.amazon.com/Ebtech-Hum-Ground-Voltage-Filter/dp/B0002E4YI8/ref=sr_1_4?crid=38KC6IFVLTI1H&keywords=Hum-X&qid=1654439417&sprefix=hum-x,aps,107&sr=8-4

There are many examples of each, just grabbed what came up in a quick Amazon search. I would start with an RCA and cable isolator and see if those work first. Put the cable isolator in line nad see if that fixes it. If not, you can leave it, and try the RCA isolator on different components. You may want to start by pulling components one at a time (including the cable or cable box) to see if one of them makes the hum go away, then you can isolate just that component.

HTH - Don

I’ll bet you’re right about cable. There’s no coax “directly” on the system, but it’s on Cat6 Ethernet from a router fed by a (Comcast) cable system. (We no longer use cable TV. We stream video via YouTube TV, etc. plus an OTA antenna for backup.) GREAT suggestions!

 

[DonH56]

I’ll bet you’re right about cable. There’s no coax “directly” on the system, but it’s on Cat6 Ethernet from a router fed by a (Comcast) cable system. (We no longer use cable TV. We stream video via YouTube TV, etc. plus an OTA antenna for backup.) GREAT suggestions!

Thanks!

Ethernet is galvanically isolated per spec so should not be the problem, but I have seen a few that mess that up... Easy and fairly cheap to try, anyway.

 

[DavidMcRoy]

Thanks!

Ethernet is galvanically isolated per spec so should not be the problem, but I have seen a few that mess that up... Easy and fairly cheap to try, anyway.

I just ordered the cable isolator.

 

[RayDunzl]

I have a device that came with a 3-prong wall plug, but the IEC connector in the device has only two of three prongs protruding.

I guess I can feel safe when I plug it into the wall and have lifted Earth ground at the same time, so I got that goin' for me, which is nice.

 

[antcollinet]

I have a device that came with a 3-prong wall plug, but the IEC connector in the device has only two of three prongs proturding.

I guess I can feel safe when I plug it into the wall and have lifted Earth ground at the same time, so I got that goin' for me, which is nice.

On the other hand - no point whatsoever in lifting the earth ground. It is already not connected.

 

[RayDunzl]

On the other hand - no point whatsoever in lifting the earth ground. It is already not connected.

Yeah, no problems here even with all the assorted stuff in the rack.

I count 18 devices and 4 lamps on three different bulk outlets from one wall plug.

 

[sam_adams]

This can be save if you have a fast blowing low current fuse for this outlet and an GFCI.
And if the device is using proper high peak current diodes.

That's a lot of 'ifs' to entrust your safety to. The Hum-X—in all of its iterations—is rated six amps max. Those diodes aren't going to survive in any line-voltage to chassis fault condition. Keep in mind that anytime the impedance of the ground line increases the breaker takes longer to trip.

 

[Lambda]

Also a lot of things that need to happen to get a fault that results in a shock and most shocks are not deadly.
I'm not saying its risk free. (nothing is).
But If you don't have an CFGI/RCD electrical safety is obviously not your propriety.

A proper diode in this package can withstand 2000 A²s once ( i don't think your 1000A for 100ms is realistic)
Still for the diode to survive 10ms or one halve cycle braking current must be limited to about 400A

Don't know about US domestic MCBS but realistic they shuld clear in under 1 halve cycle with a 10-15x overload.
So around 100A for 8.3ms for a fast 6A fuse gives abut 1000A²s so a proper diode could survive.

Even if the diode Blows up and you get shocked

Residual-current device - Wikipedia

en.wikipedia.org

400mA for 10ms is still in the green area.

With the right fuses and protection electronics it can be save.
The way some maybe uses it is not very save. still better then just removing the SG/PE

 

[sam_adams]

( i don't think your 1000A for 100ms is realistic)

 

[Lambda]

And waht are you trying to show with this?
trip time can be as long as 2.5s and fault current an be as high as 1000A
As you said yoursel the lower the imedance the faster the barker trips
but not at the same time.
especially not if you have RCD/CFGI

 

[JSmith]

Could be worth a try;

GND Defender by iFi audio - Eliminates ground loops that often cause audible speaker hum.

GND Control The GND Defender (Ground) eliminates ground loops in your audio set-up that often cause audible speaker hum.

ifi-audio.com

https://ifi-audio.com/wp-content/uploads/2021/03/iFi_GNDDefender_TechLowdown_FINAL.pdf

Auto reinstatement of ground connection to pass current if a fault is detected

JSmith

 

[Lambda]

Could be worth a try;

Its the same thing. 2 diodes back to back. maybe a capacitor and a resistor in parallel.
Fault current rating is only 220A.

100$ is allot for a (bad) solution like this.
if they would at lest build in fuses...

I would stop punting lipstick on a pig and try to find the root cause.

 

[DavidMcRoy]

I just ordered the cable isolator.

I just plugged it into the input of the modem, et voilà: no more hum, even after I removed all cheater plugs from the system. I could actually feel a tingle when touching the F-connector ahead of the filter. Four devices that are part of the AV system have hardwired Ethernet connections to a router, which is fed by the outboard modem: the AVR/Processor, a Sony 4K TV, a Sony 4K BVD player and an Apple TV 4K.

Thanks to DonH56 for the link:

https://smile.amazon.com/InstallGear-Ground-Isolator-Noise-Filter/dp/B077Y5DLBB/ref=sr_1_1_sspa?crid=1RB3JV8990DT4&keywords=rca+ground+loop+isolator&qid=1654439534&sprefix=rca+%2Caps%2C123&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFTNTA2TVZWR0k1V0EmZW5jcnlwdGVkSWQ9QTA5NjE5NTAyWk5RTzYxQU01UkNDJmVuY3J5cHRlZEFkSWQ9QTAwOTI4NTMxWU9HRllTVUk1TDdUJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

[fpitas]

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The problem there, in the USA which prong is actually neutral? We measured 25 houses for adherence to code. About 50% were wired correctly. About 50% had the neutral and hot swapped.

Besides, I'll point out the elephant dancing around: the ground wire from the socket to the breaker box really does connect to neutral at the breaker box. I guess we're being warned to not drive our own stake in the Earth for ground?

 

[asrUser]

Is it safe to lift the ground of active speakers? With ground connect my headphones inside the system will produce some humming.

 

[tmtomh]

Is it safe to lift the ground of active speakers? With ground connect my headphones inside the system will produce some humming.

Lifting the ground of an active speaker is no safer than lifting the ground of a separate amplifier.

I feel your pain, though, because if each active speaker has its own amplifier and power plug, then that's 2 grounded devices right there, and it only takes 2 to create a ground loop and produce the kind of hum you're hearing. There are methods and products that can safely help with that, though.

 

[asrUser]

Well that's strange. miniDSP support told me it's completely safe to lift the ground of my speakers (Neumann KH120A). Gotta find out myself if I get a Pikachu?