Telephone Wiring

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wrote:

[snip]
I remember reading a story about a near future, where they tested new products on people because they didn't have "animal rights".
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Jeff Wisnia wrote:

Edison labs were used for research on the electric chair, electrocuting various animals. This was part of Edison's attempt to show that AC was dangerous. The first use of an electric chair (which used AC) was horribly botched; the first attempt didn't work and the second was gruesome. IIRC using "westinghouse" to be the same as "electrocute" was part of Edison's PR campaign against AC.
There is an interesting recent book on the Edison - Westinghouse/Tesla war (the name of which I don't remember).
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wrote:

I suppose I haven't seen that book, that's just a single chapter in the one I have. That book has stories about different inventions (including Telephone and Microwave Oven).
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Not True. Electric Chairs use AC.... not DC and the voltages have varied depending on the state and locality. Sing Sing Prison was known for its higher voltage chair, in particular.
http://www.straightdope.com/classics/a1_219.html
Beachcomber
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So do I. But have you ever done it whilst in shorts sitting on bare concrete?

Ordinary shoes/carpet make a _big_ difference.

Generally speaking, if you're reasonably grounded (bare legs on concrete ;-), most people start feeling things at around 35-40V.

I assure you, your heart doesn't run at 90V.
Ringer voltage is perhaps somewhat more, um, "memorable" for two reasons. One is that it's closer to DC, which is inherently somewhat nastier than the same voltage in AC. The second, more important one, is that you're firmly grasping it thinking all is right with the world, and _zap_ out of nowhere, you get hit.
Since your muscles are already gripping it, the ringer voltage tends to keep you gripping it even harder. Longer duration contact. Maybe a whole ring cycle before you can let go.
In contrast, you don't usually have anywhere near as good a connection to line voltage when things start to hurt, and short of a "fall into" or a misguided "firm grab", the muscular reaction tends to knock your hand or finger _away_. Grab that switched off switch leg firmly, and have someone flip the switch on. That's very much different, and vastly more likely to be lethal than a mere "graze".
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On Tue, 05 Sep 2006 20:55:05 -0000, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

The on-hook voltage is DC and is going to be around 40-50 volts and the current is near zero. You can feel this under certain circumstances. The voltage drops dramatically when the phone goes off the hook to perhaps 9 volts or so. Standing on a ground is not usually a problem around telephone wires unless you are in an electrical storm. The loop (off hook) current is limited by a resistor at the phone exchange to about 20 ma or so, even if the wires are shorted together.
Long lines in rural areas might have higher loop current, but again, phone wiring is not considered dangerous except with the thunderstorm exception.
Ring voltage is going to be higher, anywhere from 90 volts AC or higher, but normally not with enough current to kill you unless you are at the top of a telephone poll and the shock you receive causes you to fall off and break your neck.
Remember, transformers only pass AC and block DC. (Telephone audio signals are considered AC even though they are really varying DC. - A transformer is said to pass the AC component of the DC as long as it is not overdriven or saturated).
Capacitors block DC and pass AC.
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Remember that 20ma is potentially lethal under some circumstances, however, getting hit by that much is _extremely_ unlikely (given voltages and normal circumstances during handling of the wire).
[Even while sitting on a concrete floor in shorts ;-)]

Well, you sit in shorts on my concrete garage floor and touch the wiring. ;-)
It's not likely to have been dangerous in terms of harm, but it was certainly enough of a tingle to make it impossible to make the wiring connections I wanted to do.
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