Melted

[Diesel]

Peeler

dopehead? You seem to be getting rather desperate.

[Peeler]

[whisky-dave]

why have it?

It is safer, you might even think it's twice as safe as 240. But even 119 is safer than 120.

Like that means anything.

it is. If it gets a muscle which closes your hand, then you grab. If it gets the muscles on the other side, you release. Which is why firemen are told to feel with the back of their hand incase of loose wires, so their ar m will jump away from the wire.

Yes it;s still better to aviod touching live wires you are correct in that if you use the back of your hand and it contracts the musles which does hap pen with an electric shock that will disconnect you rather than making grip a large conductor.

They can do and have, but for most people they only kill you once.

[NY]

No, but they hurt like hell. I've had several, luckily never across the chest which can cause cardiac arrest. Once was across the knuckle of finger, as I was probing something and forgot that while the appliance was switched off at the appliance, the terminals of that switch were still live. My whole hand jumped and I had a tingling up my arm which lasted for several hours, even though the current would have flowed directly from the live to the neutral terminal, and the amount that would have flowed up my arm would have been small. I gashed my finger badly as the muscles contracted it and forced it onto something sharp, and I still have the scars made by the two terminals.

I had a fairly old belt even via a high-resistance safety resistance from a TV, causing everything that the TV was connected to (hifi via audio cables, PC upstairs via aerial lead) to experience that voltage. I only noticed it because I had one hand on the earthed case of the PC as I was unplugging the aerial cable with the other, holding its metal plug: as soon as the plug left the earthed PC, I got a jolt. After investigation, I found that the TV's audio and aerial sockets were at about 200V, though with a human-sized resistor to mimic my body that dropped to about 80V. So I can feel 80V with dry skin.

At least I'm not hypersensitive. I knew a woman at university who could tell whether a 1.5 V AA battery was charged or dead by putting her finger and thumb across it, and found it painful to do the same to a 9V battery. Mind you she was unusual: she had a number of medical problems such as being so double-jointed that she had to be careful not to bend her limbs too far the wrong way or they would dislocate, and she had a weird syndrome which meant that if she experienced anything painful, such as a cut or a bruise, her body carried on feeling the same level of pain even after the stimulus was removed. Apparently she needed an operation for something but the surgeon advised her not to have it done because he couldn't guarantee that she wouldn't continue to feel the pain of the incision, done under general anaesthetic, for a long time after she came round when most people just feel the lingering twinge of a sutured incision.

[James Wilkinson Sword]

If it still kills people, there was no point in it. And stop oversnipping.

It means it doesn't happen, in a data set of about 10 occurrences.

I have gripped a conductor before. It was a 240V wall socket on the end of a wire which I thought was disconnected but wasn't. I picked it up and gripped it, my hand got warm and tingly, that's all.

No, for most people they just don't kill you at all.

[Diesel]

Peeler

Yet, you spend so much of your precious time responding to nearly every post a specific individual makes. If you live in the states, please consider getting a part time job at the very least. I hate the idea of my tax dollars being spent to keep you housed and fed on my dime.

[whisky-dave]

rote:

hen why have it?

As yuo lower the voltage the chance of an electric shock that can kill redu ces.

As someone else might say I'll shovel your shit where it belongs.

10 isn't exactly a large sample. Penty of people have been killed by 240V.

ful it is. If it gets a muscle which closes your hand, then you grab. If it gets the muscles on the other side, you release. Which is why firemen a re told to feel with the back of their hand incase of loose wires, so their arm will jump away from the wire.

hat if you use the back of your hand and it contracts the musles which does happen with an electric shock that will disconnect you rather than making grip a large conductor.

of a wire which I thought was disconnected but wasn't. I picked it up and gripped it, my hand got warm and tingly, that's all.

So, some people survive car accidents others don't.

But they seem to have infected yuor memery. "I think I've had around 8 240V shocks in my life." "It means it doesn't happen, in a data set of about 10 occurrences."

So only 20% differnce so far. Maybe one of those 'occurrences' f***ed your brain or which is why you can; t work out how to walk in shoes or estimate the height of doors without ban ging your head.

[Diesel]

That's a single phase transformer. It has ONE phase. One secondary coil with two taps plus a center neutral that's tied to ground. It's being fed by a single phase power source. It's not two phase, it's not antiphase, it's dual/split/single phase.

[James Wilkinson Sword]

But you can get two phases from it by centre tapping it.

[Diesel]

You aren't getting two phases...The urls I've already shared explain that concept to you.

[Tekkie®]

alan_m posted for all of us...

I always use a grease: nose, bulb, dielectric, whenever I use a screw base bulb. I think I only have one bayonet bulb in the house; for a desk lamp that hardly ever use because it gets so hot...

[Mark Lloyd]

That describes the transformer. I'm not at the transformer, but a (240V) receptacle looking at the voltages on a scope. There are TWO phases there.

[Sam E]

It doesn't matter how it's made (how many transformers, ...), but what it is. Examine a 240V outlet and you find TWO PHASES.

[NY]

It's a single phase input to the primary with two 180-degree phases of output: one in phase with the input, one leading/lagging by 180 degrees. What matters is what you see on the output, not how you achieved it from the input which is undeniably a single phase.

What are two signals that have a phase difference of 180 degrees if not "antiphase"?

Or do you only count it as being two phases if they are 120 degrees apart as supplied by different mains phases, having been generated by coils in the generator that are the same spacing?

Suppose you had a generator with two, rather than three coils. Would you distinguish between two 180-degrees-apart signals at the secondary, depending on whether they were fed from a single mains input and a centre tap secondary, as opposed to a transformer with a centre tap primary as well, fed from both mains inputs?

Quite - that's the result. I presume you are measuring each of those lines on separate oscilloscope traces wrt some common reference such as neutral.

[Sam E]

[snip]

It's a Möbius phase :-)

BTW, a Möbius strip is something that can be split and still be one thing.

[Mark Lloyd]

[snip]]

Reality is that which, when you stop believing in it, doesn't go away.

A voltage measurement requires a reference (normally this is ground), so you have a 240V transformer secondary with a grounded center tap. The voltages at the ends are 120V of opposite phase.

[Mark Lloyd]

[snip]

Yes.

[Rob]

FWIW, the old "center tap as reference" is a trick test question instructors frequently use in Electricity 101 to see if students have been paying attention.  By the time you've successfully completed Electricity 101 you realize how silly the two-phase argument/conclusion is.  The fact that the center tap is grounded really confuses some new students.

If you have a dual-trace scope, connect the common lead to L1, connect probe 1 to the center tap and probe 2 to L2.  You'll see both traces are in-phase with each other.

[Mark Lloyd]

[snip]

Apparently, it IS a matter of point of reference. Maybe you could explain your choice?

[Diesel]

He just provided you a simple way to verify for yourself that you have ONE phase, not two. It's electricity 101. You do not have two phases because you have two hot legs coming out of that transformer. It's a single split phase setup. ONE phase, in sync with one another. Not offset.