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?
If the elements were _really_ 0 Ohms then it would mean that both were
defective but in a completely shorted way. More likely you had your
meter on the wrong resistance range or, if it was on the lowest range,
that the meter doesn't go low enough.
The problem is in the wiring or a connection or the circuit element(s)
which are responsible for switching power to the element and I'm
guessing that a repair is probably not something you should see as a
HEY We all had to start somewhere! I have made lots of dumb mistakes
fixing things, and I am a service tech for over 30 years!
Cut the guy a break!
Have you checked for power at the heater when the machine is running?
Oh, the visual of this taking place with a complete amateur. Door open,
water spraying, and arms reaching in with test leads. Honey, will you hold
the meter while I check this please.
Go to www.repairclinic.com
I don't think I've done that but I've reached in to turn the water off
to a water cooler when it was plugged in and the fan was running.
(prior to this we usually had it unplugged, but we thought we were
done and plugged it back in! I didn't really hurt myself)
I agree with you that everyone makes a lot of dumb mistakes. When I
was president of my hiking club, I told people that any hike where
everyone came back alive was a success.
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.
On 11 Jun 2006 01:48:03 -0700, email@example.com wrote:
OK, but it's a tiny heater. ;-) It's designed to give light and
although maybe half of the energy makes heat, one couldn't heat the
water in the dishwasher with the heat from one lightbulb, unless it
was maybe a 1000 watt bulb.
I think one tends at first to have the same misconception I refer
above wrt lightbubls too. That the brighter bulbs have higher
resistance, because that means the electricity has to fight even
harder to get through it, and that makes more light. But in fact the
brighter bulbs have lower resistance, and more current flows, and more
light is made.
Simply put, ohms law is E=IR. E is voltage in volts, I is current in amps,
and R is resistance in ohms.
Or I=E/R; same equation.
Power is P (in watts) = IE, or (E/R)*E, or E^2/R
Power is inversly proportional to resistance.
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