1970zHiFiGuy
Active Member
A few of my components don't have polarized plugs , what year were they introduced and or become common? My Denon Dp59L still didn't have one , I think it is from 86 or 87.
polarized power plug
- Thread starter 1970zHiFiGuy
- Start date
Wiki says that use of polarized plugs goes back as far as 1948. The 3-prong grounded receptacle has been a standard since 1962, but of course you can still plug a non-polarized 2-prong cable into one.
The non-polarized IEC C9C/10 stuff was still being used in the early '80s, and lower current IEC cables are often non-polarized.
John
The non-polarized IEC C9C/10 stuff was still being used in the early '80s, and lower current IEC cables are often non-polarized.
John
woodj
Super Member
Depends what you mean by polarized, but the patterns (one lug wider than the other) used to date (as I remember) began to be used (if my memory serves) sometime mid 70's and slowly dribbled into use until they actually became pretty universal.
Those actually existed long before, but mostly in specialized applications.
Those actually existed long before, but mostly in specialized applications.
WaynerN
Addicted Member
I have Marantz equipment from the mid 70s that still didn't have polarized plugs, so I'm guessing they didn't start showing up until the 80s. I think the problem started with non-polarized plugs when components started having fuses (which can go way back), but then some dudes on the NEC board realized that without a polarized plug, the neutral could actually be the line getting fused, which would be a no-no. Some stuff still doesn't have polarized plugs, like some of my wall-warts and a couple of my lamps but that is about it.
For the most part, the 3-prong plug in a home environment is not necessary either, but there are some manufacturers that think its more impressive to ship an amp with a 3-prong ground wire. Of course, the ground wire of a 3-prong outlet, in a stereo system likes to invite gremlins into the system (ground loops) and then we as consumers have to deal with them kinds of problems.
The polarized plug is a good idea, the 3-prong plug is over the top (IMO).
Wayner
(Footnote: I have several pieces of paper from the NFPA-79e that says I passed their courses on the subject of electrical fire hazards and safety, but that doesn't make me king of anything).
For the most part, the 3-prong plug in a home environment is not necessary either, but there are some manufacturers that think its more impressive to ship an amp with a 3-prong ground wire. Of course, the ground wire of a 3-prong outlet, in a stereo system likes to invite gremlins into the system (ground loops) and then we as consumers have to deal with them kinds of problems.
The polarized plug is a good idea, the 3-prong plug is over the top (IMO).
Wayner
(Footnote: I have several pieces of paper from the NFPA-79e that says I passed their courses on the subject of electrical fire hazards and safety, but that doesn't make me king of anything).
c.coyle
Fighting the Dunning-Kruger effect.
I bet liability concerns also have something to do with that.
whoaru99
Epic Member
Ground loops are often the fault of a problem in the systems of the house, not that the of equipment with grounding conductor. For example, faulty/poor bonding of the CATV service drop to the dwelling grounding system is not uncommon. This can result in ground loop problems. Devices with the grounding plug may cause that bonding problem to be revealed, but they didn't cause the bonding problem. Nor does use of two-prong plug make the root cause (the poor/faulty bond) go away.
As to the Code, generally it's about safety, not whether using equipment grounding causes noise in your stereo. If it does, maybe look to an underlying cause, not a cheater plug, et al. I'm not saying that is your implication, just making a general statement.
JRhoBurton
All roads lead to music
It's occurred to me that one (non-rigorous) test for "true vintage" is having a non-polarized plug. I don't think anything in my cabinet right now has a polar plug.
I asked a younger electrician about these recently and he did not seem to understand how such plugs would even be possible.
John
I asked a younger electrician about these recently and he did not seem to understand how such plugs would even be possible.
John
AC is a mystery to me. The ground wire and the neutral wire both go to the same bus bar, which is then earth grounded. There is no neutral/return cable from the entrance panel to the line transformer.
It's like the electricity is gone, once the potential is used.
cycletemp
New Member
Try this at home
Here's how it was explained to me a long time ago.
Today's scientific question is: What in the world is electricity? And where does it go after it leaves the toaster?
Here is a simple experiment that will teach you an important electrical lesson. On a cool, dry day, scuff your feet along a carpet, then reach your hand into a friend's mouth and touch one of his dental fillings. Did you notice how your friend twitched violently and cried out in pain? This teaches us that electricity can be a very powerful force, but we must never use it to hurt others unless we need to learn an important electrical lesson.
It also teaches us how an electrical circuit works. When you scuffed your feet, you picked up a batch of "electrons," which are very small objects that carpet manufactures weave into carpets so they will attract dirt. The electrons travel through your blood stream and collect in your finger, where they form a spark that leaps to your friend's filling, then travels down to his feet and back into the carpet, thus completing the circuit.
AMAZING ELECTRONIC FACT: If you scuffed your feet long enough without touching anything, you would build up so many electrons that your finger would explode! But this is nothing to worry about, unless you have carpeting.
Although we modern persons tends to take our electric lights, radios, mixers, etc. for granted, hundreds of years ago people did not have any of these things, which is just as well because there was no place to plug them in. Then along came the first Electrical Pioneer, Benjamin Franklin, who flew a kite in a lightning storm and received a serious electrical shock. This proved that lightning was powered by the same force as carpets, but it also damaged Franklin's brain so severely that he started speaking only in incomprehensible maxims, such as, "A penny saved is penny earned." Eventually, he had to be given a job running the post office.
After Franklin, came a herd of Electrical Pioneers whose names have become part of our electrical terminology: Myron Volt, Mary Louise Amp, James Watt, Bob Transformer, etc. These pioneers conducted many important electrical experiments. For example, in 1780 Luigi Galvani discovered that when he attached two different kinds of metal to the leg of a frog, and electrical current developed and the frog's leg kicked, even though it was no longer actually attached to the frog, which was dead anyway. Galvani's discovery led to enormous advances in the field of amphibian medicine. Today, skilled veterinary surgeons can take a frog that has been seriously injured or killed, implant pieces of metal in its muscles, and watch it hop back into the pond just like a normal frog, except for the fact that it sinks like a stone.
But the greatest Electrical Pioneer of all was Thomas Edison, who was a brilliant inventor despite the fact that he had little formal education and lived in New Jersey. Edison's first major invention, in 1877, was the phonograph, which could soon be found in thousands of American homes, where it basically just sat until 1923, when the record was invented. But Edison's greatest achievement came in 1879, when he invented the electric company. Edison's design was a brilliant adaptation of the simple electrical circuit: The electric company sends electricity through a wire to a customer, then immediately gets the electricity back through another wire, then (this is the brilliant part) sends it right back to the customer again. This means that an electric company can sell a customer the same batch of electricity thousands of times a day and never get caught, since very few consumers take the time to examine their electricity closely. In fact, the last year in which any new electricity was generated in the United States was 1937. The electric companies have been merely re-selling it ever since, which is why they have so much free time to apply for rate increases.
Today, thanks to men like Edison and Franklin, and frogs like Galvani's, we receive almost unlimited benefits from electricity. For example, in the past decade scientists developed the laser, an electronic appliance that emits a beam of light so powerful that it can vaporize a bulldozer 2,000 yards away, yet so precise that doctors can use it to perform delicate operations on the human eyeball, provided they remember to change the power setting from "VAPORIZE BULLDOZER" to "DELICATE."
Here's how it was explained to me a long time ago.
Today's scientific question is: What in the world is electricity? And where does it go after it leaves the toaster?
Here is a simple experiment that will teach you an important electrical lesson. On a cool, dry day, scuff your feet along a carpet, then reach your hand into a friend's mouth and touch one of his dental fillings. Did you notice how your friend twitched violently and cried out in pain? This teaches us that electricity can be a very powerful force, but we must never use it to hurt others unless we need to learn an important electrical lesson.
It also teaches us how an electrical circuit works. When you scuffed your feet, you picked up a batch of "electrons," which are very small objects that carpet manufactures weave into carpets so they will attract dirt. The electrons travel through your blood stream and collect in your finger, where they form a spark that leaps to your friend's filling, then travels down to his feet and back into the carpet, thus completing the circuit.
AMAZING ELECTRONIC FACT: If you scuffed your feet long enough without touching anything, you would build up so many electrons that your finger would explode! But this is nothing to worry about, unless you have carpeting.
Although we modern persons tends to take our electric lights, radios, mixers, etc. for granted, hundreds of years ago people did not have any of these things, which is just as well because there was no place to plug them in. Then along came the first Electrical Pioneer, Benjamin Franklin, who flew a kite in a lightning storm and received a serious electrical shock. This proved that lightning was powered by the same force as carpets, but it also damaged Franklin's brain so severely that he started speaking only in incomprehensible maxims, such as, "A penny saved is penny earned." Eventually, he had to be given a job running the post office.
After Franklin, came a herd of Electrical Pioneers whose names have become part of our electrical terminology: Myron Volt, Mary Louise Amp, James Watt, Bob Transformer, etc. These pioneers conducted many important electrical experiments. For example, in 1780 Luigi Galvani discovered that when he attached two different kinds of metal to the leg of a frog, and electrical current developed and the frog's leg kicked, even though it was no longer actually attached to the frog, which was dead anyway. Galvani's discovery led to enormous advances in the field of amphibian medicine. Today, skilled veterinary surgeons can take a frog that has been seriously injured or killed, implant pieces of metal in its muscles, and watch it hop back into the pond just like a normal frog, except for the fact that it sinks like a stone.
But the greatest Electrical Pioneer of all was Thomas Edison, who was a brilliant inventor despite the fact that he had little formal education and lived in New Jersey. Edison's first major invention, in 1877, was the phonograph, which could soon be found in thousands of American homes, where it basically just sat until 1923, when the record was invented. But Edison's greatest achievement came in 1879, when he invented the electric company. Edison's design was a brilliant adaptation of the simple electrical circuit: The electric company sends electricity through a wire to a customer, then immediately gets the electricity back through another wire, then (this is the brilliant part) sends it right back to the customer again. This means that an electric company can sell a customer the same batch of electricity thousands of times a day and never get caught, since very few consumers take the time to examine their electricity closely. In fact, the last year in which any new electricity was generated in the United States was 1937. The electric companies have been merely re-selling it ever since, which is why they have so much free time to apply for rate increases.
Today, thanks to men like Edison and Franklin, and frogs like Galvani's, we receive almost unlimited benefits from electricity. For example, in the past decade scientists developed the laser, an electronic appliance that emits a beam of light so powerful that it can vaporize a bulldozer 2,000 yards away, yet so precise that doctors can use it to perform delicate operations on the human eyeball, provided they remember to change the power setting from "VAPORIZE BULLDOZER" to "DELICATE."
whoaru99
Epic Member
Power is delivered/consumed because of the voltage drop across the load, but there is still current flowing through both conductors of the circuit.
gslikker
Super Member
Yes you are right.
Although the 3 prong plugs in Europe are different (in many countries you can turn them around either way) it is about safety.
Many vintage equipment NOT grounded is not really safe, indeed.
Or worse, really UNSAFE.
The death cap stressed against the metal I found in my HK Citation on the picture is the perfect example of something mounted by an idiot.
WaynerN
Addicted Member
Yes you are right.
Although the 3 prong plugs in Europe are different (in many countries you can turn them around either way) it is about safety.
Many vintage equipment NOT grounded is not really safe, indeed.
Or worse, really UNSAFE.
The death cap stressed against the metal I found in my HK Citation on the picture is the perfect example of something mounted by an idiot.
B.S. If you plan on playing your ungrounded stuff while standing in water on top of concrete while hanging onto your metal case of the equipment, and then that component has a fault where the load line comes in direct contact with the metal case.........Then your body could become part of the circuit.
I have 8 power amps in the house, 3 are fairly new and none of them have a 3-prong grounded plug.
American homes have 2 120 volt lines and a neutral coming into the box. To get 240 volt, the 2 120 volt lines are in series to run things like your stove, furnace and electric dryer.
The safety ground (the "ground wire") eventually goes to a copper rod, pounded into the ground outside your house. This ground is in case the other ground (neutral) goes to hell.
I guess you guys should read up a bit on device safety classes as well as mains power network topologies (e.g. TN-C/TN-C-S, TT, IT) - 'cause due to the differences of these it's typically not quite possible to give a general answer on what would be the best practice for a particular system combination at a particular place...
Greetings from Munich!
Manfred / lini
Greetings from Munich!
Manfred / lini
whoaru99
Epic Member
That grounding wire is not there in case the neutral goes to hell. Here's why not; I believe NEC says the earth ground is to be 25 ohms or less. Let's say it is roughly half what NEC allows, 12 ohms. If you have a 120V ground fault and the return path is 12 ohms, there will be 10A of current. That's not enough fault current to trip the (typically) 15A or 20A or larger overcurrent devices. So, you can see the grounding rod is ineffective at providing the return path for low voltages.
The safety grounding wire is to provide a low impedance fault current path back to the source so the fuse blows/breaker trips rather than the chassis of the device being at potentially dangerous voltage. The common use the term grounding/grounded here is somewhat misleading because it's actually bonding as the primary function.
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gslikker
Super Member
Guess my house is TN-S but I can not look further where it comes from and do not know about the electricity company grounding scheme .
At least the cap in my example being in a metal device having no ground connection, I do not think it complies to any safety class
BTW in Holland grounding of metal parts like central heating radiators is mandatoy in bathrooms and other wet places. It has to be a separate grounding net using tinned 4 mm copper to where the ground wire comes into the house.
Ground fault interrupters are mandatoy also, for many years already. Guess in Germany it will be about the same?
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