Cheap fix on Ground Loop

[NOSValves]

No even one is not acceptable............ but please show me just "one" with a home audio system setup like I suggested....please show me. If it happens there has to be a record of it some where.......the fact of the matter is a failure so bad that it could fry the inter connecting cables ground conductor would also fry the fuse and most likely fry the fuse before the inter connecting cables grounding conductor could fry... This is all much to do about nothing.

http://forums.anandtech.com/showthread.php?t=2139639

Although that was a PC, a stereo receiver could do the exact same thing for the exact same reason.

No if done in an audio/video system as I have suggested it could not happen...I have never stated one should lift the entire system from ground unless using a properly setup GFI outlet (which by way is safer then a grounded system). This PC user was supplying his computer with a path to ground.

[NOSValves]

I wouldn’t even want the theory of a chance.

I was once at my father in laws house. Short story, he needed a new heating element in his water heater. No problem… I can do that.

Find the breaker to the heater and kill it. I did the “glug glug glug” method where you quickly pull out the old one and stuff in the new one losing very little (but some) water in the process. This instead of draining the entire tank.

As this happened, I ended up sitting in a bit of water since it had nowhere to go but the floor.

I then felt a distinct but on the mild side, shock.

Perplexed…. I reached out to touch it again. (by now, I don’t know if I was trying to unwire the old element, wire in the new element…. I just know that I was sitting in a puddle of water (mild puddle) and was getting shocked every time I touched the darn thing.

Fearing that something was cross-wired, I told the wife to get me a flashlight and then simply go kill the panel to the entire house.

I didn’t want to play Dick Tracy while getting mild (but confirmed) shocks. I didn’t wire it, I’m not an electrician and don’t like to glow in the dark.

She killed the power and I CONTINUED to get shocked as I put it back together.

We finally managed to piece it together with nobody getting hurt.

Told brother in law (electrician) and he pretty much immediately knew the issue and called the power company.

Seems they had one of their power lines out in the woods, snap and was laying on the ground. My understanding is I became the conduit for those volts that were seeking to go home. Took them almost two days to fix it as they had to re-string some part of it.

Coytee no offense intended but for you to keep working on wiring the water heater while getting shocked with the power turns off at the service panel is the definition of boneheaded....glad you made it through it alive....

Edited December 16, 2014 by NOSValves

[babadono]

Page 8:

http://www.aes.org/sections/pnw/pnwrecaps/2005/whitlock/whitlock_pnw05.pdf

 

A more complete up to date version of this is available at the Jensen Transformers website. Mr. Whitlock knows what the heck he is talking about. His document is the one that has the electrocutions stats in it. And the document he references is: http://www.cpsc.gov/PageFiles/136139/2009electrocutions.pdf. And no the government report does not break down how many or if any deaths were caused by a lifted ground.

[JL Sargent]

To add some perspective to this. On average, 90 people die per day in the US by car wreck. 33K died Jan to Dec 2012. If you want to get alarming about something!

[babadono]

I wouldn’t even want the theory of a chance.

 

I was once at my father in  laws house.  Short story, he needed a new heating element in his water heater.  No problem…  I can do that.

Find the breaker to the heater and kill it.  I did the “glug glug glug” method where  you quickly pull out the old one and stuff in the new one losing very little (but some) water in the process.  This instead of draining the entire tank.

 

As this happened, I ended up sitting in a bit of water since it had nowhere to go but the floor.

 

I then felt a distinct but on the mild side, shock.

 

Perplexed….  I reached out to touch it again.  (by now, I don’t know if I was trying to unwire the old element, wire in the new element….  I just know that I was sitting in a puddle of water (mild puddle) and was getting shocked every time I touched the darn thing.

Fearing that something was cross-wired, I told the wife to get me a flashlight and then simply go kill the panel to the entire house.

I didn’t want to play Dick Tracy while getting mild (but confirmed) shocks.  I didn’t wire it, I’m not an electrician and don’t like to glow in the dark.

 

She killed the power and I CONTINUED to get shocked as I put it back together.

 

We finally managed to piece it together with nobody getting hurt.

 

Told brother in law (electrician) and he pretty much immediately knew the issue and called the power company.

 

Seems they had one of their power lines out in the woods, snap and was laying on the ground.  My understanding is I became the conduit for those volts that were seeking to go home.  Took them almost two days to fix it as they had to re-string some part of it.

Richard,

 Glad to hear you survived that. But to make it clear to everyone, a power line was broken and on the "ground" and yet the electricity went through you because YOU became less of a resistance to "ground" standing in water and touching metal parts that are "grounded" and bonded to neutral.

[babadono]

To add some perspective to this. On average, 90 people die per day in the US by car wreck. 33K died Jan to Dec 2012. If you want to get alarming about something!

And this too is a terrible tragedy.

[Beechnut]

Why does my Onkyo receiver have a 2 wire power cable instead of a 3 wire?

[Rhetor]

I hav read the whole thread . . . I can do the small home repair electrical stuff.

So, for all of my vintage 2 prong electrical (amps, etc.) and even my newer stuff, I use the three prong surge protector strips with high joules . . . am I all good?

The only hum through the speakers I ever get is brief when turning on the two-prong Phase Linear 400 running my fronts in the HT. (Transformers warming up?)

[Beechnut]

Ground loops can cause hum's in your system. If you don't hear any hum that is bothering you, then don't change a thing.

 

The OP wanted to share his cheap solution to fixing a ground loop that was causing and audible hum that was annoying.

[CECAA850]

Why does my Onkyo receiver have a 2 wire power cable instead of a 3 wire?

 

Probably double insulated like a hair dryer, drill, etc.

[JL Sargent]

Double insulation symbolA Class II or double insulated electrical appliance is one which has been designed in such a way that it does not require a safety connection to electrical earth (US: ground).

The basic requirement is that no single failure can result in dangerous voltage becoming exposed so that it might cause an electric shock and that this is achieved without relying on an earthed metal casing. This is usually achieved at least in part by having two layers of insulating material surrounding live parts or by using reinforced insulation.

[babadono]

And please don't jump all over me if i am wrong about this but I think the big manufacturers have to go through an approval process (like UL) to get their products approved "as double insulated" or non hazardous without a safety ground.

[JL Sargent]

Nearly all electrical appliances sold in the US have to meet Nationally Recognized Testing Laboratories (NRTL) approval, UL is only one of such outfits. Double insulated is only one class of electrical device these folks provide certification for.

[NBPK402]

And please don't jump all over me if i am wrong about this but I think the big manufacturers have to go through an approval process (like UL) to get their products approved "as double insulated" or non hazardous without a safety ground.

Anyone that wants to display the UL label has to have the item tested by UL, and pay the associated fees for displaying the UL logo. Also when an item is tested and passes it is only valid in the state that it was tested... ie a computer fan gets UL approval and then adds a heat sink...now it is no longer approved.

[Paducah Home Theater]

I have recently noticed some notice if I have my sub gain up too high. I think it is fan noise though. Need to modify the amp to use a quiet pc fan. Hopefully that will fix it but I'm not sure.

[Andy W]

 

 

Don,

Are you bit of an alarmist? In an audio/video system the inter-connecting cables pass ground from one device to the next....as long as one device has an earth ground they all have earth ground...the added 3 wires power cable is what completes the loop! The only way a piece of gear could become a danger is if the inter connecting cables either went up in smoke or were disconnected. Yup using cheater plugs does lower the safety margin a minute amount but geezzzz it's not as big of a deal as you're making out to be...

 

It really is a big deal - that is, if you value your life or the lives of your family. Grounding through interconnects is definitely not a good idea. I'm going to say it again: use cheater plugs only as a diagnostic aid, then remove them and fix the problem properly.

 

 

 

Josh my "personal" preferred method is no earth ground at all...I use GFI protection which IMHO is about as safe as safe can be.

 

This is a good, safe method. The NEC preferred method for GFCI connection is 2 wire ungrounded. However, the fact that a ground loop occurs is evidence that conventional 3 wire safety ground type circuits are in use.

 

 

 

 Good grief.....show me the statistics that support your claim of extreme danger............for instance back in the day that high voltage tube electronics ruled the day not a single device came equipped with a 3 wire grounded power cord.... show me the statistics to support large numbers of death by electrocution from such devices.

 

   Again I'm not arguing the fact that a grounded power cord adds a very small degree of safety....but to state that running without a ground is a sure fire way to death is just silly! The truth is the chances of harm are about a million to one....

 

 

Disconnecting the ground is not a sure fire way to die, but keeping it is adds a layer of protection to prevent death.

 

The two big protections it gives are shock and fire.

 

And yes, it is the million to one child that is killed that is the reason for the earth ground on certain equipment.  And if you are the designer of the equipment or the company that sells it, it's that one child that you care about.

 

You should care too.

 

There are two kinds of insulation, single and double (or reinforced).  In the international safety standards they are referred to as Class 1 and Class 2 insulation.  Equipment also has to have certain distance (called creepage and clearance) between hazardous live and accessible conductive parts (like the metal chassis of an amplifier).  Class 2 equipment requires a larger distance than Class 1.

 

Class 1 equipment is required to have a 3rd earth ground conductor on the  AC mains cable.  Class 2 equipment does not have the earth ground.  Apples and Oranges.

 

The extra layer of insulation (in internal wiring, transformers, extra creepage and clearance) in Class 2 equipment prevents electric shock in the case of failure of the first layer of insulation.

 

Failure of the insulation in Class 1 equipment (example: vibration causes a sharp edge on a chassis to cut through the single layer of insulation) results in the chassis becoming "hot" or "live".

 

If the insultation doesn't fail, then no one gets hurt.  It's the failure (the "million to one") that we worry about.  I have been shocked myself on a ceiling fixture that had a cut ground wire.  I haven't touched anywhere near a million ceiling fixtures, so the odds are much higher than 1:10^6 IMO.

 

However, when you disconnect the ground, you don't automatically get shocked.  True.  Unless there is a failure...

 

But, you say, the interconnects are there to keep the chassis grounded, as long as any one piece of equipment is groundeded...

 

Well, not so fast...

 

There is one important thing that the ground wire provides that the interconnects cannot... The ground wire in the AC mains cable is sized and rated appropriately to carry the FULL FAULT CURRENT of the AC mains.  And the insulation must be rated VW-1 (vw stands for vertical wire and it passes a flammability test).  Most interconnects can't do that either, unless they are rated to be installed in walls.

 

The current rating of the earth ground guarantees that when the fault occurs and the full AC mains current flows from the Hot to the Chassis to the Earth ground that the AC mains breaker will open, removing the shock and fire hazard.

 

The internal "signal ground" connection wiring, pcb traces and small RCA cables aren't going to carry 15 Amps of 120VAC in fault conditions. they will as you say, "[go] up in smoke", leaving the chassis still very "live" and still very dangerous.

 

A GCFI will work (they fail too), but not all AC plugs have it, and someone could easily say, "This outlet isn't working, I'm going to try that one."  ZAP!

Edited December 17, 2014 by Andy W

[babadono]

The current rating of the earth ground guarantees that when the fault occurs and the full AC mains current flows from the Hot to the Chassis to the Earth ground that the AC mains breaker will open, removing the shock and fire hazard.

Only cuz ground is bonded to neutral

[JL Sargent]

"the AC mains breaker will open"

 

My AC mains are 200 amp. Surely you are talking about a branch circuit consisting of a typical 15amp breaker?

Edited December 18, 2014 by JL Sargent

[Beechnut]

 

 

Disconnecting the ground is not a sure fire way to die, but keeping it is adds a layer of protection to prevent death.

 

The two big protections it gives are shock and fire.

 

And yes, it is the million to one child that is killed that is the reason for the earth ground on certain equipment.  And if you are the designer of the equipment or the company that sells it, it's that one child that you care about.

 

You should care too.

 

There are two kinds of insulation, single and double (or reinforced).  In the international safety standards they are referred to as Class 1 and Class 2 insulation.  Equipment also has to have certain distance (called creepage and clearance) between hazardous live and accessible conductive parts (like the metal chassis of an amplifier).  Class 2 equipment requires a larger distance than Class 1.

 

Class 1 equipment is required to have a 3rd earth ground conductor on the  AC mains cable.  Class 2 equipment does not have the earth ground.  Apples and Oranges.

 

The extra layer of insulation (in internal wiring, transformers, extra creepage and clearance) in Class 2 equipment prevents electric shock in the case of failure of the first layer of insulation.

 

Failure of the insulation in Class 1 equipment (example: vibration causes a sharp edge on a chassis to cut through the single layer of insulation) results in the chassis becoming "hot" or "live".

 

If the insultation doesn't fail, then no one gets hurt.  It's the failure (the "million to one") that we worry about.  I have been shocked myself on a ceiling fixture that had a cut ground wire.  I haven't touched anywhere near a million ceiling fixtures, so the odds are much higher than 1:10^6 IMO.

 

However, when you disconnect the ground, you don't automatically get shocked.  True.  Unless there is a failure...

 

But, you say, the interconnects are there to keep the chassis grounded, as long as any one piece of equipment is groundeded...

 

Well, not so fast...

 

There is one important thing that the ground wire provides that the interconnects cannot... The ground wire in the AC mains cable is sized and rated appropriately to carry the FULL FAULT CURRENT of the AC mains.  And the insulation must be rated VW-1 (vw stands for vertical wire and it passes a flammability test).  Most interconnects can't do that either, unless they are rated to be installed in walls.

 

The current rating of the earth ground guarantees that when the fault occurs and the full AC mains current flows from the Hot to the Chassis to the Earth ground that the AC mains breaker will open, removing the shock and fire hazard.

 

The internal "signal ground" connection wiring, pcb traces and small RCA cables aren't going to carry 15 Amps of 120VAC in fault conditions. they will as you say, "[go] up in smoke", leaving the chassis still very "live" and still very dangerous.

 

A GCFI will work (they fail too), but not all AC plugs have it, and someone could easily say, "This outlet isn't working, I'm going to try that one."  ZAP!

 

Andy,

 

I'm in the same camp with you on my understanding. The extra safe grounding from the 3-wire systems is great for safety, and I know that doesn't mean that 2-wire is unsafe. Multiple paths to ground can become problematic for audio and radio systems.

 

I know a few Ham operators, in efforts to reduce RFI (radio frequency interference) and ground loops, they have power circuits in their house that have their own panel, which nothing else is plugged into but their radio equipment. They take great care to ensure there is only 1 path to ground. The cheaper way to do it is to run your gear off a battery bank system.

 

In my theater equipment, there is a very very small hum that I can only hear if I shut off the A/C in the house, and get about a foot from the speaker when the system is on, with no audio playing. If it bothered me, I'd chase after the source. I might notice it if I had a dedicated room with room treatments.

[babadono]

 

If a good ground/neutral does not exist in your circuit you can simply make one by hammering a ground rod into the earth and wire the ground up to your circuit(s), i have seen cold water lines and conduit used also but normally it will not be to code but most places have their own rules for this so be sure to follow them.

Good, sound, advice here.

 

Sorry I missed this earlier

NEVER, NEVER, NEVER add another grounding rod to your house to try and eliminate 60 Hz hum. Grounding rods on equipment outside your house are for lightning strikes and you will note they do not get bonded to the neutral conductors in your house wiring. If you have a problem(or think you do) with the ground rod at your service connection and its connection with neutral call an electrician.