On Sat, 10 Jun 2006 18:57:57 -0500, "jonlevy" wrote:

I'm trying to fix the "hot dry" function on my dishwasher--as is, I get no
steam, no heat, and no drying. After seeking some advice, I removed the
heating element and tested its resistance with a multimeter. It said 0
OHMs! I figured it was broken and got another, but that says 0 too!! Does
this make sense?

don/'t let this bother you. It's like learning to walk. A baby has to
fall down a few times, many times, to learn how to walk.

Your reasoning made sense if this had been a motor or even iirc a
lightbulb or just about anything other than a heater. Heaters use a
lot of current. Much more current is needed to make heat than to make
motion or light, so the resistance has to be a lot lower. fairly close
to zero, to let all that current flow through. (one tends to think
that it would have substantial resistance, and the electricity would
fight its way through like the US Army at the Arno river, and this
fighting with the resistance (whatever that means) would make the
heat, but that's not the way it works, not the right analogy.) OTOH
if the resistance were really literally zero, too much current would
flow and things would melt.

But the real clue was that the heating element you tested was
U-shaped, right? That is, one end was separted physically from the
other end. (I-shapped heating elements like in toaster ovens are the
same thing, topologically.)

So there really can't be a short circuit that would make the
resistance go to zero. There could be an open circuit, but that would
make the resistance infinite. But if say, the heating element has a
wire coil in it, the most that could short would be two adjacent
loops. Out of maybe 100. So the resistance would go down 1 percent.
Or 10 out of 100 for 5 percent. But the first loop can't short
against the last loop, because it is probably 18 inches away via the
curve of the heating element. I'm not explaining this well, but do
you see why when one end is an inch away from the other end, through
empty space via a straight line, there can't be a short circuit that
would result in zero ohms?

OTOH, if you had a lamp or something with a cord coming into it,
through a rubber grommet, and the grommet fell apart, and the metal
that surrounded the grommet cut into the cord and connected the two
wires which were only a quarter inch apart, that would cause a short
with infinitesimal, almost zero resistance.