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

drlegendre . drlegendre at
Thu Nov 27 13:39:23 CST 2014

Hi Chuck,

The lack of heating in your antimagnetic stainless or copper cookware isn't
due to a lack of ferromagnetic content - it's a different situation
entirely. The issue stems from the electrical properties of the bulk
material - in essence, those pots are +too good+ of a conductor at the
frequencies in use. The currents flow in a deep, thick layer and encounter
trivial resistance. It's this lack of resistance that's responsible for the
lack of heat production .

I'm sure you've seen the well-known 'magnet down the copper pipe'
demonstration, which shows clearly that eddy currents develop just fine in
copper - which certainly isn't in the ferromagnetic series. As for glass or
ceramic, they're electrical insulators, so there's little to zero current
flow at all, and again, no heat production.

On Thu, Nov 27, 2014 at 1:00 PM, Chuck Guzis <cclist at> wrote:

> On 11/27/2014 06:17 AM, Mouse wrote:
>  (But it has its own downsides, like not working with glass pans - I
>> have a glass skillet....)
> It's more serious than that.  The cooking utensil has to be
> ferromagnetic.  So, my substantial investment in 18/10 stainless steel
> cookware is out; however, cheap 18/0 stainless works fine.  My Le Creuset
> porcelain-over-cast iron are fine as are my All-Clad stainless.
> I have a considerable inventory of older borosilicate Pyrex (not the cheap
> soda-lime that passes for Pyrex nowadays) as well as pieces of Corning
> glasswre that are more than 40 years old.  Those get relegated to ovenware
> and storage.  Fortunately, better makers of cookware are now starting to
> laminate a steel insert into pot bottoms.  Given the low thermal
> conductivity of glass, I've wondered if cooktop use can be justified  But
> induction's come a long way since Princess Margaret started using it.
>  Interesting!  What _does_ account for most of the draw?  Are you in an
>> area where electric is common as the energy source for routine heat?
>> Thinking about my own experience, I'm fairly confident the ranking goes
>> heating (if electrical), computers, cooking, and then everything else
>> is down in the noise - and that's for me personally; most people don't
>> have nearly the computer load I do.
> Other than living space heating, I understand that a water heater accounts
> for a substantial part of an all-electric home's energy consumption.
> Lighting also used to be high on the list, but since CFL adoption has
> picked up, I don't think that it accounts for the load that it once did.
> Eventually, LEDs can be expected to supplant CFLs.
>  I've wondered about that.  SMPSUs draw no current most of the cycle,
>> drawing heavily on the peaks, without the smoothing effect of the mains
>> transformer present in (most) non-switching supplies.  This is almost
>> nothing like most historical load, which is mostly either resistive or
>> inductive.  I'm curious whether it has a significant effect on the
>> grid; do you happen to know?
> "Dirty" harmonic-laden current from SMPSUs is a problem.  But that problem
> also arises from the lowly CFL.  Right now, the problem is being mostly
> ignored.   I read an interesting paper that suggests that HVDC for large
> server farms may be the best answer in that case.
> --Chuck

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