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From: grege@gold.gvg.tek.com (Greg Ebert)
Newsgroups: sci.electronics
Subject: Re: polarity
Message-ID: <2237@gold.gvg.tek.com>
Date: 26 Apr 91 16:30:44 GMT
References: <1991Apr24.111307.2296@dcs.simpact.com> <2226@gold.gvg.tek.com> <1991Apr26.035007.2804716@locus.com>
Distribution: usa
Organization: Grass Valley Group, Grass Valley, CA
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I (Greg Ebert) wrote:

Almost. 120V RMS sinusoids are actually 340 v p-p, or 170 v peak.

dana@locus.com (Dana H. Myers) writes:

>  I know I'm the one who claimed that power is dissipated in capacitors a
>while back (ugh!), but I do not believe 120VRMS is 340V p-p. It is 170V p-p.
>

For sinusoids, Vpeak = Vrms * sqrt(2), or Vpeak = 120*1.414 ~ 170 Volts.
Vpeak-peak = 2 * Vpeak (for symmetrical waveforms), or Vp-p= 340 Volts.

Stick a scope on the hot lead (but please be careful !).

Perhaps some confusion arises because on a standard 240V circuit (I mean
single-phase), *both* leads are hot, and *both* are 340 V p-p with respect 
to ground. One might infer that a 120 V circuit is half of this.