Three prong vs two.

[Zygmo]

Hey, Guys. I am a little nervous because I was warned about an inflammatory answer I made to a post, and had no idea that is what it was. I thought I was asking an honest question.

Sooo, to continue carefully. I have a Marantz system, with a 2020 tuner, and a 1050 integrated amp. These came installed in a small metal Marantz rack mount. This system had a strange power hook-up...proprietary three (round prong) cords plugged into a central box, which had a standard 3 prong plug for the wall. Caused a real messy bunch of cords! Makes no sense to me. So, in order to use these components separately elsewhere, I removed the original cords, and installed standard power cords. However, I used large black cords like you get on desktop computers, two flats and one round prong for ground. Having now moved these components back into the marantz cabinet, those large (stiff) cords are creating the problem of using so much room in the back of the cabinet.

I would like to put standard, zipcord power cords in place of these large ones. My question is....can I safely use a two wire cord, in place of the two wire with ground cords? All my extension cords only have the two wire (one larger blade), so I am using the 3 wire to 2 wire adapters. How would I wire this two wire cord inside the amp and tuner cabinets to eliminate all these problems? What would I do about the missing third, ground prong connection? BTW, this integrated amp is probably only 30 WPC, or so.....huge power cords are not necessary at all.

Which leads to this. Years ago, all cords were 2 wire. Then we went to virtually all small appliances and audio components coming with 2 wire with ground. Now we are back to mostly two wire, with one wider blade. Why was it ok to have 2, then we had to have 3, now it is ok to have 2 again??!

 

[qdrone]

From 2 to 3 and back could be the way houses are built today code wise.

 

[triode17]

My question is....can I safely use a two wire cord, in place of the two wire with ground cords?

The short answer is ......no. The long answer is, if all the devices are Double Insulated, then yes. As long as there is no easy way to touch any metal inside the device. But you may also lose any filter circuit action, that shunt noise to ground. My advice, buy 18 gauge three prong (IEC) cables with thin jackets. They're out there , we use them at work.
If you can safely solder, you could also shorten each cable by cutting out a piece, then splicing the two halves together. That should leave you enough room inside the rack.
Yamaha is known for including thick, 16 gauge IEC cables with units that draw 20 Watts. Major overkill, but they probably need them for their large power amps, so its cheaper to buy 16 ga. in bulk, than buying 16 and 18 ga. cables.

 

[WaynerN]

The real answer is...unless you are playing your system on wet concrete or near a pool, there is little chance of any problem at all. The 3 prong cord introduced into the hifi world is a JOKE, implemented by people that profit from huge, grounded power cords that serve no purpose.

 

[pskaudio]

The real answer is...unless you are playing your system on wet concrete or near a pool, there is little chance of any problem at all. The 3 prong cord introduced into the hifi world is a JOKE, implemented by people that profit from huge, grounded power cords that serve no purpose.

Wrong! They serve two purposes. One: So it looks like your amplifier can draw mucho power through that inch and half diameter trunk. Two: So you can purchase another tweak employing questionable techno babble in it's advertisements.

If you meant to say no practical purpose, than I have to agree.

 

[Roadrash]

The real answer is...unless you are playing your system on wet concrete or near a pool, there is little chance of any problem at all. The 3 prong cord introduced into the hifi world is a JOKE, implemented by people that profit from huge, grounded power cords that serve no purpose.

Posts like this are why I love this forum. I've wondered if there would be any good reason to 'upgrade' the power cords from the original two prong cords on my L-09Ms. Now I know.

 

[pskaudio]

Posts like this are why I love this forum. I've wondered if there would be any good reason to 'upgrade' the power cords from the original two prong cords on my on my L-09Ms. Now I know.

I understand completely. I've got a pair of the L-07M IIs and the cords look so thin and wimpy, but they are fine for your (rare and cool ) amps and mine.

 

[E-Stat]

This system had a strange power hook-up...proprietary three (round prong) cords plugged into a central box, which had a standard 3 prong plug for the wall. Caused a real messy bunch of cords!

Help me understand how using a three prong plug makes for a "messy bunch" of cords. Most of my gear uses code compliant plugs - messy?

 

[biscuithead]

Older two prong plug = didn't matter where neutral was (mostly) ... wide brush.

Three prong plug = ensured neutral to neutral, hot to hot and included equipment ground.

New two prong plug = the wider blade is neutral and ensures correct neutral to neutral , hot to hot .

There are many different appliances, equipment , applications and uses for each cord and plug configuration. UL , IEC, and NEC have more to do with which is chosen than marketing or "jokes".
Code compliance and engineering isn't a joke, unless house fires and deaths are funny....

On that "zip" cord you mention... ever notice the side that has a stripe or ribs in it? That designates the neutral.

The requirements that have changed throughout the years, are to be blamed on data, observations, and safety.

 

[Roadrash]

I understand completely. I've got a pair of the L-07M IIs and the cords look so thin and wimpy, but they are fine for your (rare and cool ) amps and mine.

That's exactly the same description I would have used for the cords on the L-09s. I kind of figured if the engineers and designers thought the cords needed to be heavier they would have made them that way to begin with, since the L series gear wasn't exactly built to a price point. They sure do look out of place though.

 

[Zygmo]

E-stat....the mess wasn't due to them being three pronged....it was because there was three components all with large, stiff, too long white cords going to a fairly large white box. From there, a large white stiff cord went to the wall outlet. All that was crammed into an area 16 inches wide, by 6 inches tall at the bottom of this small cabinet. (The front is standard rack mount width, but the back narrows down.) As you can see by the picture, I am working on a bottom portion tall enough to hold vinyl albums, but it won't be open to the back.

This originally came with the amp, tuner, matching cassette deck, and turntable.

So now I am still not sure whether I can install small, 2 wire cords into the amp, and receiver. I have installed a small Denon cassette deck, that has it's original, small 2 wire cord. I made the rack mount plate for it, and now have to figure out how to put the grain in the aluminum, and give it some champagne color to match the rest.

 

[Zygmo]

Older two prong plug = didn't matter where neutral was (mostly) ... wide brush.

Three prong plug = ensured neutral to neutral, hot to hot and included equipment ground.

New two prong plug = the wider blade is neutral and ensures correct neutral to neutral , hot to hot .

There are many different appliances, equipment , applications and uses for each cord and plug configuration. UL , IEC, and NEC have more to do with which is chosen than marketing or "jokes".
Code compliance and engineering isn't a joke, unless house fires and deaths are funny....

On that "zip" cord you mention... ever notice the side that has a stripe or ribs in it? That designates the neutral.

The requirements that have changed throughout the years, are to be blamed on data, observations, and safety.

Biscuithead....when using zip cord for speaker wire, I always used the ribbed side for the positive terminal. LOL
So...what is your opinion about wiring up to the inside of the two components with two wire cord?

As Triode17 suggested, I could shorten these two large cords. That would certainly be be the neatest solution. Quite a bit of work to make the finished splice look good though. I've never used shrink tubing that large.

 

[blhagstrom]

Where ARE you?

There was a pissing contest on another thread about adding a third wire to ground the vintage system and increase the wire size. Total BS.

IF you have US 110-120v gear on a US 120v power grid. The third wire is BS and you can lose that dumb f**k monster power cords.

70s vintage gear used unpolarized 18ga “zip cord” AC cords except on the monster gear.

Open your gear. Look at the white and black AC connections. That’s where you tap a 2 wire AC cord on. The green is probably tapped with the white. If the green goes to chassis, I’m surprised you don’t have a hum.

I chop off polarized 2 wire replacement all the time and put the unpolarized 2 wire back all the time. The accessory sockets on the back are unpolarized and the wide blade on polarized won’t fit.

The AC line goes into the unit through a strain relief. Hopefully they didn’t f**k up the original hole so you can replace the strain relief in the normal cord. Once inside, one AC line taps directly to the transformer. The other goes through the main fuse, through the power switch to the transformer. Many times all of that is very secure with straps and or held in looms.

That’s it. The rest of the system is secondary winding off the power transistor and that only goes to the bridge rectifier then to the filter caps.

Everything after the filter caps is DC powered. The audio signal is a low voltage AC that rides in top of the DC.

So, the only thing the AC main does is energize the transformer to create the required AC secondary voltage to power the DC system.
There may be some low voltage taps running a light or two.

There is nothing about powering the transformer that requires polarity.

Lose those stupid monster power cords.

All the talk about bigger power cords working better or sounding better is pure BS. All the AC goes through the main fuse. A tiny little thin wire.

 

[bimasta]

I have a fine Meitner power amp, 100W, with a 3-prong plug. Hum was louder than the music. I tried a 2-prong cheater plug — hum gone.

 

[WaynerN]

Older two prong plug = didn't matter where neutral was (mostly) ... wide brush.

Three prong plug = ensured neutral to neutral, hot to hot and included equipment ground.

New two prong plug = the wider blade is neutral and ensures correct neutral to neutral , hot to hot .

There are many different appliances, equipment , applications and uses for each cord and plug configuration. UL , IEC, and NEC have more to do with which is chosen than marketing or "jokes".
Code compliance and engineering isn't a joke, unless house fires and deaths are funny....

On that "zip" cord you mention... ever notice the side that has a stripe or ribs in it? That designates the neutral.

The requirements that have changed throughout the years, are to be blamed on data, observations, and safety.

No it doesn't. We have a wide blade neutral....... can't switch the plug around.

Electricity needs a path to follow. If you decide to become a path. There are all kinds of electrical appliances and lamps that still come with a 2 prong plug. I have also recently bought new hifi stuff that still has a 2 prong plug.

 

[biscuithead]

Biscuithead....when using zip cord for speaker wire, I always used the ribbed side for the positive terminal. LOL
So...what is your opinion about wiring up to the inside of the two components with two wire cord?

As Triode17 suggested, I could shorten these two large cords. That would certainly be be the neatest solution. Quite a bit of work to make the finished splice look good though. I've never used shrink tubing that large.

Zip cord speaker wire : a wire only has two ends, it won't complain about about how it is used.

Two wire cord: just make sure the hot and neutral go where they should go, if it matters. The wire gauge needs to be the appropriate size for the FLA (full load amperage) .

It is true that adding a three prong cord to a piece that didn't originally have a three prong cord, then bonding the ground to chassis, could cause a hum. Depends on the piece.
My personal opinion: stick with OEM. If a cord needs to be replaced because of damage, do a like for like replacement.

I have a drawer full of old 14awg Electric skillet power cords that I've picked up at thrifts over the years. I love the insulation material ( don't know what it is ), it is very pliable. I use these usually on old tube gear that the cord is damaged. Works great.

 

[biscuithead]

No it doesn't. We have a wide blade neutral....... can't switch the plug around.

Electricity needs a path to follow. If you decide to become a path. There are all kinds of electrical appliances and lamps that still come with a 2 prong plug. I have also recently bought new hifi stuff that still has a 2 prong plug.

I don't think you understand my words.

The three prong plug configuration of a cord ensures the correct mating of said plug to the receptacle ( the thing in your wall that provides the traveling electrons to your device )
This assumes that the recept is wired correctly.
The nature of the three prong plug disallows it to be turned upside down. It is stupid proof... too bad my words weren't.

I do not dispute that two prong cord connected equipment still exists, with no reason to be grounded.

I have already stated that the wide blade neutral ensures this as well.
Before the advent of the wide blade, there was the three prong (usually for commercial use) . It's purpose was both to provide a ground, if needed, and to ensure hot to hot, neutral to neutral connectivity when plugged in. I have seen many applications in my career where a three prong cord was used, yet inside the equipment the ground wire was isolated and not utilized. This was done for the same reason the wide neutral was invented.

Nothing to be contentious about .

 

[JP]

Some remarkably bad advice here, and far too many misconceptions to address.

Will dropping PE cause you issues? Chances are it won’t. The edge cases in this situation include 1) someone could get electrocuted and 2) a fire could be started. Not likely, but possible. If your’re happy accepting that risk and the associated liability, then by all means...

 

[WaynerN]

The two prong plug is polarized. It can't be inserted the wrong way. Neutral will be to neutral, line to line.

There is no reed for a ground if your equipment is used properly, like not outside in the rain or on wet concrete, or down in your damp basement. Even then, the equipment has to have a problem with it. There is a "but" with this. Older, non-polarized plugs, like on old Dynaco, Marantz, vintage stuff needs to be treated a little different. It is possible to insert the plug in any which way, and on some units, there can be a slight problem if certain circumstances are present.

In my town, a woman was electrocuted using a stainless steel butter knife to remove some lodged toast from a toaster. She was in the kitchen, the kitchen was in an older house, it did not have GFCI outlets in the kitchen and she somehow during the dislodging process, became part of the current carrying conductor. Since it only takes about 10-12 ma to kill (freezes the heart), she perished.

We also had a service man killed in town repairing a microwave oven. He did not get electrocuted, rather energized by the microwave element, which apparently cooked his head and he did not realize what was happening.

I am not opposed to the wide spread use of the 3-prong plug, but with the codes dealing with GFCI outlets in kitchens, bathrooms, basements, garages and outdoor outlets, there is little fear of a problem getting electrocuted or starting a fire.

I was a T4 electrical designer for a fortune 500 company, had to pass an electrical test every year (must score 100%) and take the NFPA-79e refresher course every year. This course was graphic, showing examples of how the human body suffers at the hands of 3-phase shorts, etc.

I also think that the new outlets with spring loaded neutral and line inserts is going overboard. Perhaps I do believe in the "Buffalo Theory".

 

[WaynerN]

Some remarkably bad advice here, and far too many misconceptions to address.

Will dropping PE cause you issues? Chances are it won’t. The edge cases in this situation include 1) someone could get electrocuted and 2) a fire could be started. Not likely, but possible. If your’re happy asking that risk and the associated liability, then by all means...

I think that people need to be educated on what real electrical hazards are and how to avoid them. BTW, low voltage can also kill. All it needs is a path thru your heart and lungs and it will freeze the muscles. Our bodies work on electrical signals.

Other hazards to avoid is replace blown fuses with a different type or higher size then specified, operating equipment with frayed cords, operating equipment where it is exposed to the elements or sources of heat or water. Many older garages do not have GFCI, so if you are running a stereo out there on concrete and your stereo has a metal cabinet and faceplate, you might want to install a GFCI outlet. The GFCI is really the true hero here.

Manufacturers are providing 3-prong cords with their equipment because they fear the consumer's ignorance, and the lawyer's knowledge. I have seen people use electrified products in the worse possible conditions and not think anything of it. One in particular comes to mind, a band playing outside during a rainstorm (lighting and electrocution) with no shelter. Dumb.