Somewhat OT Knob & Tube wiring (was Re: Power and the RA82)

Not quite. When one sees (say) "120V AC", that 120V *is* the RMS value; "120V" is actually 120/sqrt(.5) = about 170V peak. (Assuming a pure sine wave, that is, which is close enough for practical purposes when dealing with mains power.) As for "kinda DC-equivalent", it *is* equivalent as far as mean power delivered into a purely resistive load goes, which is why that measure is used: 120 RMS volts AC into (say) 120 ohms will dissipate as much power, long-term average, as 120 volts DC into the same load. (RMS here stands for Root-Mean-Square, which is a thumbnail description of the mathematics involved: it's the square root of the mean value of the square of the instantaneous voltage. This is derived thus: let the voltage, as a function of time, be v(t). The current into a load of resistance r will then, by Ohm's law, be i(t)=v(t)/r and the power will be i(t)v(t), or v(t)^2/r. If we now work let c be the constant DC voltage necessary to dissipate the same amount of power, average, we find that c^2/r=mean(v(t)^2)/r, leading directly to the RMS formula. sqrt(2) comes into it because that's what the RMS computation produces when v(t) is a pure sine wave.) Only if you start with the peak AC voltage, which is not what voltmeters normally indicate when measuring AC voltages. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse at rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B