Residental electrical load [was Re: Who's rewired their house for this hobby?]

Johnny Billquist bqt at
Fri Nov 28 01:22:16 CST 2014

On 2014-11-28 06:51, drlegendre . wrote:
> Hey Chuck,
> On Thu, Nov 27, 2014 at 2:11 PM, Chuck Guzis <cclist at> wrote:
>> This goes counter to my experience.  Any utensil that passes the "magnet
>> test" will work; any that don't, don't.
>> I've never found an exception to this.
> In retrospect, my comments may have been a bit pedantic - as you have
> found, the 'magnet test' is more than likely an effective method for
> selecting compatible cookware.
> The point of my post, was that it's not actually the presence or lack of
> ferromagnetic characteristics which are responsible for the compatibility
> or incompatibility of the given cookware. Let me see if I can explain this
> without further muddying the waters:
> I think we all understand that induction heating is the result of eddy
> current propagation within the cookware - this is one of the reasons that
> it's more efficient than traditional contact-coupled resistive elements
> operated off AC mains power. But like any _resistive_ heating element, the
> cookware must offer sufficient _resistance_ to the impressed currents to
> produce any heating effects - that's just I^2*R.
> In the case of most copper, antimagnetic stainless or aluminum vessels, the
> eddy currents actually propagate a bit too well - that is, the effective
> resistance of the imposed current path is too low for any useful ohmic
> heating to take place. In other words, the currents flow, but the voltage
> drops are inconsequential.
> Or that's how I understand it. As ever, I await my ongoing education.. ;-)

That sounds a bit weird, as I would expect the current resistance in 
iron should be pretty low as well. Or is it really way higher than in 
copper or aluminium?

The magnetic properties seems to be the common factor in my experience 
as well. Not sure how they relate to electric resistance...


Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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