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No grounding?

motaboy

motaboy

Active Member
I'm sorry uf this is a bit of a silly question, but if you never ask you never learn :yes:

I have a G9000. I am wondering why the electicity plug (the one the goes to the wall outlet, you know) hasn't got the 3rd wire for grounding.
On such a powefull amp, doesn't it need some "real" ground incase anything goes wrong? Can't you die from all the power going through there? :scratch2:
Where does all the grounding go to then?
 
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Actually, I've asked myself this! It's not silly at all, IMHO. The power cord on my Yamaha amp looks so small it's not funny; just about big enough for a table lamp, and no ground plug. I would have thought at least high wattage amplifiers would have grounding plugs on them!
Tom
 
We didn't worriy about such stuff back in those days. Only after the 'Ground Police" decided that we must be protected from the evil ungrounded outlets that 3 wire plugs came into being. Of course they didn';t fit into any existing home outlets. So then they invented the 3 to 2 prong adapter where you could plug your new wonderful 3 wire plug, then plug into a 2 wire ungrounded outlet therby defeating the whole purpose. So we can thank govt regulation for the 3 wire plugs.
All 2 wire power cords for home appliences are/were rated for 15 amps(~1500 watts). Look at toasters and small space heaters and hair dryers and such things.
 
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My knee jerk reaction is that perhaps the third wire ground could cause ground loops when you tie it all together with Correct grounding using something like battleship braid. One ground point with minimal contact resistance, that does not seem to favor that ground on the plug. All the little diagrams they send with the equipment when it was new showing proper grounding tends to get tossed with the plastic bag and the warranty card.
Try to get proper shortwave reception without a good ground, good luck....
 
motaboy said:
I'm sorry uf this is a bit of a silly question, but if you never ask you never learn :yes:

I have a G9000. I am wondering why the electicity plug (the one the goes to the wall outlet, you know) hasn't got the 3rd wire for grounding.
On such a powefull amp, doesn't it need some "real" ground incase anything goes wrong? Can't you die from all the power going through there? :scratch2:
Where does all the grounding go to then?
Click to expand...

These amps have power transformers and the AC input does not need a ground. In fact adding a ground to the amp and to all the other equipment would create what are called ground loops. Ground loops occur when there is a way for ground current to travel in a loop between equipment. This creates noise on the ground which can be heard in the amp. For example you have your amp connected to the AC with a ground and your source (CD, tape, TT or whatever) also connected to the AC with a ground. When you connect the equipment together you create a ground loop from the Amp though the connecting cables to the source, from the source to ground through the AC plug to the ground on the AMP through the AC plug then back to the source. Without the ground on the AC line the "Loop" is broken and therefore no current can flow in the ground. Current on the ground = noise.

On equipment that does have a ground plug the AC ground and the signal grounds are isolated from one another so that there is no current flow between the two.

As to the size of the AC cord. A fifteen amp circuit in your house only requires 14 gauge wire. So for most amps a 16 or even 18 gauge power cord is acceptable. (The AC line on most of the high powered amps is fused at 10 amps which means that they probably draw a maximum at max volume of between 5 and 6 amps on the AC line)

Hopefully that clears the mud a little
 
Jim, thanks for that great answer.
I am aware of gound loops, and I know that when you run in to humm comming from a ground loop problem it can be a b*tch to solve sometimes, but seeing as newer equipment comes with grounding I was wondering.
Oldhifiguy explained the situation pretty good too (I wasn't even born when my amp was made :) )

So they were more worried about ground loops than they were about getting hurt from faulty equipment, right?
 
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motaboy said:
Jim, thanks for that great answer.
I am aware of gound loops, and I know that when you run in to humm comming from a groun loop problem it can be a b*tch to solve sometimes, but seeing as newer equipment comes with grounding I was wondering.
Oldhifiguy explain the situation pretty good too (I wasn't even born when my amp was made :) )

So they were more worried about ground loops than they were about getting hurt from faulty equipment, right?
Click to expand...

The newer amps separate the signal grounds from the power grounds. that way they can have a grounded power plug without creating ground loops.
 
I see. Cool. Do feel like explaining why an amp with a power transformers and the AC input does not need a ground?
 
Note that the power line has a 'hot' and a 'neutral' side. If you have a VOM you can determine which way of plugging the amp into the wall puts the amp's housing on the neutral side [VOM connected from housing to ground]. You can then mark the prong that was in the wide slot in the wall recepticle (a Sharpie will do), and always plug it in that way in future.

If this instruction is unclear it may be because I am unsure of my facts.

Bob
 
motaboy said:
I see. Cool. Do feel like explaining why an amp with a power transformers and the AC input does not need a ground?
Click to expand...

Transformer power supplies don't need a ground and it doesn't matter which way the cord is plugged in because neither the hot or neutral are connected to the chassis. Both leads are connected to the transformer through the switch. Note that they are not connected directly to the chassis.
 
Now I see why when I hold my electric guitar (hooked to it's own amp of course), and touch my G9000, I get cheezed :D
 
The residential grounding standard was changed for safety reasons only, such as Motaboy is experiencing. The receiver case is floating, meaning it has no true reference to ground. If a voltage reading is taken between the two devices where the shock is occurring you will most likely see about 60VAC. Safety grounding and signal isolation grounds are two separate beast as is grounding for a RF antenna ground plane. The neutral conductor is a common carrier of current where the safety ground is not considered a current carrier unless something has gone wrong. In the real communications world you have the VAC ground and you have an isolated signal ground. The only common point between these two grounds should be the ground stake. You could Easley install a ground buss with a single connection to the house AC ground behind your equipment and run all case grounds to that single point.

You might want to check your electric guitar and amp just to insure they are not contributors to the problem.

I really haven’t a clue about the subject matter but I did sleep at a Holiday Inn Express last night.
 
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Completed replacing transistors on a Kenwood 4140. AM is now is working and FM only working with an external antenna. Seems odd as my Pioneer SX-535 Works fine with a simple dipole. Noted the 2 lead power cord for the Kenwood may have had a cat chew through the wires. (Wish I saw that) As recall some cats at the house I purchased the unit.

Now my grounding question. If upgrading the cord, would it be best to just use a grounded cord and connect the ground wire to the ground lug? (Typical on back of old receivers)

Also a newer cord often has one prong larger or so called a polarized plug. So what rule of thumb does the hot lead go too? Thinking the power switch. But recall the old school trick of flipping an unpolarized plug in the wall to reduce RF interference. Thoughts or direction would be appreciated.
 
jisake1 said:
Also a newer cord often has one prong larger or so called a polarized plug. So what rule of thumb does the hot lead go too? Thinking the power switch. But recall the old school trick of flipping an unpolarized plug in the wall to reduce RF interference. Thoughts or direction would be appreciated
Click to expand...
The larger prong is the Neutral (blue) and the smaller is Live (brown)
 
jisake1 said:
Completed replacing transistors on a Kenwood 4140. AM is now is working and FM only working with an external antenna. Seems odd as my Pioneer SX-535 Works fine with a simple dipole. Noted the 2 lead power cord for the Kenwood may have had a cat chew through the wires. (Wish I saw that) As recall some cats at the house I purchased the unit.

Now my grounding question. If upgrading the cord, would it be best to just use a grounded cord and connect the ground wire to the ground lug? (Typical on back of old receivers)

Also a newer cord often has one prong larger or so called a polarized plug. So what rule of thumb does the hot lead go too? Thinking the power switch. But recall the old school trick of flipping an unpolarized plug in the wall to reduce RF interference. Thoughts or direction would be appreciated.
Click to expand...
You have responded to a post from 2005. Sadly CDfixer passed away in 2019. It would be nice to hear from him again though. He really left his mark on AK in many ways.

- Pete
 
LBPete said:
You have responded to a post from 2005. Sadly CDfixer passed away in 2019. It would be nice to hear from him again though. He really left his mark on AK in many ways.

- Pete
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Thanks for the heads up and sorry for the loss. New here. If there is a way to terminate the thread, let me know. I hit the UNWATCH button on top.
 
jisake1 said:
Thanks for the heads up and sorry for the loss. New here. If there is a way to terminate the thread, let me know. I hit the UNWATCH button on top.
Click to expand...
No worries, no real harm in reviving an old post. I just wanted to alert you that you won't get a response from some of the original posters in this thread.

Hitting "unwatch" means you won't get notified when there is a new post. I think you need to be a subscriber to delete your own thread. Otherwise you need to get a moderator involved.

- Pete
 
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