Andy W.'s hum and buzz blog post

[Erik Mandaville]

In the interest of safety and because this issue has been 'discussed' (I use that word loosely) in the past, it's something I think important to address. Has to do with the use of the handy cheater plug as a means of lifting the earth safety ground on component chassis. As mentioned in the past, there was a time where I also found the ground lift an easy way to solve ground loop problems between components, and remember one time I loaned an amp to a friend and grabbed a power cord from my cord/interconnect/cable box that still had a cheater plug on it. In short: A bad thing.

Andy writes in his blog about this topic very well.

Erik

[Guest " "]

An interesting point....some gear only use a 2 prong cord, others a three prong cord.  My TV is 2 prong, my Amps are three prong, my DVD/CD will accept a 3 prong cord but only uses 2 of the prongs, my DAC a three prong.  I can buy a Japan power cord that will convert a 3 prong to a 2 prong.  And sure, there are those 59 cent cheater plugs.  Is the hazard the cheater plug or the use of 2 prong cords?

 

Should I ground my TV, should I ground my DVD.....are they unsafe....obviously there are some ground look possiblities here. 

 

Whats the real hazard, my stuff is all UL rated and came this way from the factory.  How do I recreate the hazard?  Stand in a pan of water, wire the pan to the ground screw of an outlet, start licking my gear?

 

My toaster oven is a 2 wire plug as well, so are most clocks, lamps, soldering guns, etc.

 

Most older audio gear is 2 prong, we all know what happens if you  convert them to three prong.

 

 

 My 1000 dollar JVC receiver was 2 prong, so is my pioneer turntable.

  

 

 

[Guest " "]

a few more

space heater 2 prong

tea pot 2 prong

clock radio 2 prond

shaver 2 prong

ionizer 3 prong

cell charger 2 prong

laptop power supply 2 prong

 

everything that I said was 3 prong, when sold overseas, it's wired for 2 prong.

 

 

[Erik Mandaville]

Obviously this doesn't apply to ALL applicances. I suggest reading the Blog for the information you want.

[Cut-Throat]

a few more

space heater 2 prong

tea pot 2 prong

clock radio 2 prond

shaver 2 prong

ionizer 3 prong

cell charger 2 prong

laptop power supply 2 prong

everything that I said was 3 prong, when sold overseas, it's wired for 2 prong.

I read the blog completely and it did not answer all of the questions that I had either. In fact it raised more questions for me than it answered.

Consider his chandelier example: I just wired a dimmer switch on a chandelier for a friend of mine in his older house. He only has 2 wires, so the ground was not connected at all. These houses in South Minneapolis are mostly all like this. Does the owner now call 911?

Yes a ground is a safety item and should be used. Just like seat belts should be used as well, but when I grew up cars did not have seat belts.

If you have a ground loop and cannot get rid of it by any other means than disconnecting your CD player from your pre-amp, does that mean you cannot listen to CDs anymore or have to listen to them with the 60 cycle hum in the backround - I think not!

[NOSValves]

Does a study exist that shows how many people have been seriously electricuted resulting in bodily harm by using 2 pronge power cords or bypassing 3 pronge with an adaptor? I've never heard of it happening........

Craig

[Travis In Austin]

Of course to do it right you have to bring in a dedicated line from the street. Then you need to sink a dedicated copper rod (6' long right?) into the ground so the dedicated circuit has a dedicated ground. Of course, when you still have hum, trying a cheater plug is a good start. []

I read the article and thought it was very good. What I took from the grounding discussion is that if, a big if, the insulation should become frayed, the breaker is not going to operate like it should if you have not grounded it. They are going to get a shock if they grab the lamp.

Some of the items listed as having two prong plugs have their own breakers, fuses, etc. The other thing that has come along is GFI circuits. The first time I saw this is in a home I built in the 80's. They were in each bath, and two of the bathrooms were ganged on one GFI circuit. In our house now there are 8 seperate circuits. Kitchen, garage, each bathroom has a circuit, and the outside outlets are on a circuit.

I do know that when I had my 2 prong MX110 preamp you could pick up a slight buzz/jolt/shock when switching interconnect on the back if you were not careful. I have not had that happen with a three prong preamp.

[Cut-Throat]

I found this little article interesting and it in fact describes the actual ground loop that I have isolated in my Gear and they also agree that the cheater plug is the only solution, even though it is not recommended. Notice it says that home audio gear 3 prong plugs are almost unheard of. Yeah maybe if you buy your gear at Walmart! - "And the only solution would be to somehow disconnect the power line ground from one of the chassis'. This is not approved by electrical inspectors and fortunately doesn't need to be done in home stereo equipment."

Ground Loops

Figure 1. Ground loop involving line cords.

Both the preamp and power amp are equipped
with 3 wire line cords and 3 prong plugs. (Note: this is almost unheard
of in home audio equipment. This example is given for illustration
purposes only). The green wire in each line cord is connected to the
chassis of each unit. The ground prong of each plug connects to the
local power ground. The two chassis' are also connected together by the
shields of the audio cable. The audio cables are much longer than
indicated in the diagram.........................................

What can be done?

In the case of Figure 1.

You might try grounding the two chassis'
together with very heavy wire in an attempt to short out the induced
voltage. The added wire will just create another loop unless you place
it physically very close to the audio cable. Even if you do that all
you will succeed in doing will be to reduce the volume of the hum but
it will still be audible.

You might also try bringing the line cords
close together and close to the audio cable but most likely all you
will accomplish will be to increase the hum. You will place AC carrying
conductors into close proximity with the audio cables thus inducing
more hum than you are getting rid of.

The only sure way is to break the loop.
Cutting the shields on the audio cable rarely works with unbalanced
inputs. There will always be a potential difference between the two
chassis' even though they are grounded to the power line ground. The
reason is that the grounding wire gets a current induced in it because
it is in such close proximity to the current carrying conductors of the
line cord. If this were a real situation, the only solution would be to somehow disconnect the power line ground from one of the chassis'. This is not approved by electrical inspectors and fortunately doesn't need to be done in home stereo equipment.

[DrWho]

For what it's worth, I've been the recipient of such a shock and it was not nice at all. I was 14 at the time, following the advice of some stupid old fart that convinced me it was totally safe. People should take more responsibility when giving advice on things they don't understand.

It is always possible to get rid of a ground loop without lifting the third prong. All it takes is sitting down and tracing the ground paths.

If a third prong needs to be lifted, then get a GFCI strip and leave the prong alone.

[Cut-Throat]

For what it's worth, I've been the recipient of such a shock and it was not nice at all. I was 14 at the time, following the advice of some stupid old fart that convinced me it was totally safe. People should take more responsibility when giving advice on things they don't understand.

It is always possible to get rid of a ground loop without lifting the third prong. All it takes is sitting down and tracing the ground paths.

OK, solve the above example that I actually have and am currently using a cheater plug.

[DrWho]

http://www.prosoundweb.com/studyhall/sr/whitlock/grounding.php

[Cut-Throat]

http://www.prosoundweb.com/studyhall/sr/whitlock/grounding.php

No, No, No.......... Don't give me another treatise to read on grounding. Just tell me how to solve the above example!

Edit: - I did read the link you posted. It was probably the most lame post on ground loops I've ever read! The article only describes the problem, which we are all aware of. I am looking for a solution and you are dodging the question I asked!

[Guest " "]

one of my favorites for helping chase down ground loops is this japan power cable

http://www.cablesandkits.com/international-cables/power-cord-columbia-p-275.html

 

price is 10 bucks.  it converts at 3 prong appliance to use a 2 prong plug.....what I like about it is the green wire that you can screw on to the plug center screw and unscrew as required to help determine if you have a ground loop issue.  This avoids cheater plugs which some think are unsafe and eliminates the need to cut off the ground prong which is also thought to be unsafe.

 

I had a case where I could not find the source of the hum.  tried everything.  even wound up replacing all the caps in the amp.  I found out it was a ground loop when I accidentally used a japan power cord instead of a USA one.  The hum was gone.  The japan power cord does not by default use the ground prong.

 

yeah, you guessed it...this is how the folks overseas use USA appliances which can be switched to their voltage...they use a 3 prong female to 2 prong male cable...it's safe overseas, but for  what ever reason, thought to be unstafe in the US to use 2 prong cords.....I guess I need to throw out my shaver, space heater, soldering guns, TV, DVD player, clock radio, clocks, toaster ovens, lamps, AC chargers, etc.

 

 

 

 

[DrWho]

http://www.prosoundweb.com/studyhall/sr/whitlock/grounding.php

No, No, No.......... Don't give me another treatise to read on grounding. Just tell me how to solve the above example!

Edit: - I did read the link you posted. It was probably the most lame post on ground loops I've ever read! The article only describes the problem, which we are all aware of. I am looking for a solution and you are dodging the question I asked!

The article suggests the use of a GFCI.

Bill Whitlock has more technical articles on the subject if that's what you're after...I'll see if I can't dig them up, but for now I need to get back to the lab...

[Islander]

I had a case where I could not find the source of the hum. tried everything. even wound up replacing all the caps in the amp. I found out it was a ground loop when I accidentally used a japan power cord instead of a USA one. The hum was gone. The japan power cord does not by default use the ground prong.

yeah, you guessed it...this is how the folks overseas use USA appliances which can be switched to their voltage...they use a 3 prong female to 2 prong male cable...it's safe overseas, but for what ever reason, thought to be unstafe in the US to use 2 prong cords.....I guess I need to throw out my shaver, space heater, soldering guns, TV, DVD player, clock radio, clocks, toaster ovens, lamps, AC chargers, etc.

Not all 2-pronged appliances are built the same. For a long time, high-draw items had 3-prong connectors, then the "double-insulated" power tools, like drills, came out. They were described as being just as safe as 3-prong devices because of their insulation. Low-wattage items like shavers and clock radios seem okay without the third prong, but does your toaster, microwave or space heater come with a 2-prong plug? Mine all have 3-prong plugs.

[NOSValves]

For what it's worth, I've been the recipient of such a shock and it was not nice at all. I was 14 at the time, following the advice of some stupid old fart that convinced me it was totally safe. People should take more responsibility when giving advice on things they don't understand.

It is always possible to get rid of a ground loop without lifting the third prong. All it takes is sitting down and tracing the ground paths.

If a third prong needs to be lifted, then get a GFCI strip and leave the prong alone.

Maybe your shocking experience explains a few things.

Craig

[Cut-Throat]

http://www.prosoundweb.com/studyhall/sr/whitlock/grounding.php

No, No, No.......... Don't give me another treatise to read on grounding. Just tell me how to solve the above example!

Edit: - I did read the link you posted. It was probably the most lame post on ground loops I've ever read! The article only describes the problem, which we are all aware of. I am looking for a solution and you are dodging the question I asked!

The article suggests the use of a GFCI.

Bill Whitlock has more technical articles on the subject if that's what you're after...I'll see if I can't dig them up, but for now I need to get back to the lab...

I see you edited your original post. I do happen to have GFCI on the circuit that I have lifted the ground on. That was my solution.

However your statement that "It is always possible to get rid of a ground loop without lifting

the third prong. All it takes is sitting down and tracing the ground

paths" Still has not offered a solution.

[Guest " "]

"does your toaster, microwave or space heater come with a 2-prong plug?"

space heater is 2 prong

toaster oven is 2 prong

microwave is 3 prong

 " For a long time, high-draw items had 3-prong connectors"

 does not seem to be a standard, even amoung the same manufacure...I had a top of the line  receiver that drew over 1000 watts that had a 2 prong cord, the top of the line model that replaced it which drew over 1200 watts had 2 prongs, the current top of the line model came with 2 power cords a detachable 3 prong female to 2 prong male and a detachable 3 prong female to 3 prong male.  Thats how I obtained the first japan power cable.

 

 

 

[michael hurd]

Cutting off a 3rd prong, using a "cheater plug" and other means are by far the lazy person's approach. All equipment that has 2 prongs are built different than 3 prong equipped devices. Ensuring that the chassis all have the same potential, you can run a ground wire between the components. This wire attaches to the chassis of gear, you might have even seen a small screw on the back of something with GND over it.... ever wonder what that is for?

Introducing the Behringer DCX 2496 into my system I had a slight ground loop hum.... how did I fix it? I unplugged it and plugged it into the same circuit as the amplifier.That fixed the problem. There are also isolation transformers that could be used inline between components to eliminate this. I have been relatively lucky and have only had to deal with this a few times. Each time, the fix was easy. I fixed a ground loop hum between a mixer and power amps with a simple 18 gauge wire that connects to the ground screw on all. ( they had a screw that was designated GND ) If they do not have a screw that is marked chassis ground, sometimes you can use any screw on the chassis.

[Cut-Throat]

Cutting off a 3rd prong, using a "cheater plug" and other means are by far the lazy person's approach. All equipment that has 2 prongs are built different than 3 prong equipped devices. Ensuring that the chassis all have the same potential, you can run a ground wire between the components. This wire attaches to the chassis of gear, you might have even seen a small screw on the back of something with GND over it.... ever wonder what that is for?

Introducing the Behringer DCX 2496 into my system I had a slight ground loop hum.... how did I fix it? I unplugged it and plugged it into the same circuit as the amplifier.That fixed the problem. There are also isolation transformers that could be used inline between components to eliminate this. I have been relatively lucky and have only had to deal with this a few times. Each time, the fix was easy. I fixed a ground loop hum between a mixer and power amps with a simple 18 gauge wire that connects to the ground screw on all. ( they had a screw that was designated GND ) If they do not have a screw that is marked chassis ground, sometimes you can use any screw on the chassis.

You have been lucky and this is not easy, otherwise there would not be the discussions on this topic. bTW - when you ran a ground wire between the chassis you probably did not 'fix' the problem, but just reduced the hum quite a bit.

If the fix is easy, just give me the solution for the problem I posted, since the writer thought the only solution was 'the lazy person's approach'.