[C320-list] Mystery

[John Frost]

Very odd indeed.

I don't have my circuit diagram here, but I would expect three wires from
the circuit panel to your pump. 

One is the return (ground) that brings current back from the motor. It is
always at ground and therefore can't short to ground. Leave it alone.

One carries power from the panel switch manual position to the hot lead of
the motor. You describe this circuit as OK. Leave it alone

The last carries power from the auto position of the panel switch through
the float and then to the hot lead of the motor. This is where you
experience a circuit breaker trip and where to look.

A short anywhere between the panel and the float isn't the problem because
it only happens when your float activates.

I don't think a simple short on the outlet side of your float switch would
cause your symptom since I assume it is wired to the same motor contact as
the manual leg and any short on it would show up there too..NORMALLY.

If your symptoms are really what you think, here are some possible oddball
failure modes that COULD theoretically cause them:

1. A failure inside your float switch that grounds out the incoming circuit
without normally grounding the outgoing circuit. Since replacing it didn't
fix it, I'd rule that out

2. A short on the outlet side of your float switch AND an open or high
resistance from that point to the motor. Check the resistance from the float
switch outlet to the hot lead of the motor and also to ground. To the motor
should be almost zero and to ground should be thousands of ohms. Make sure
this wire actually goes to the HOT lead of the motor. If someone wired it to
the ground, that's your problem. (My bet)

3. A failing motor drawing excessive current or weak circuit breaker AND a
poor (but not open) connection in your manual leg that I said to leave
alone. Check its end to end resistance and the current draw of the motor.

Bottom line is first recheck your symptoms (They seem odd) and then make out
a drawing of your circuit and check all combinations of the two hot legs.

Good Luck!
"Better Living Through Electricity" 

John Frost
2007 C320 MKII, Hull # 1118
Lake Guntesville, AL
>
>  -------------- Original message ----------------------
> >
> > On Thu, Jul 17, 2008 at 11:40 AM, <hcreech at comcast.net> wrote:
> >
> > > OK, I need to solicit the aid of those on the list that send out posts
> > > regarding electrical problems.  You know who you are, the one's that
> send
> > > out posts that I, and I suspect, very few on the list understands.
> > > Here is my mystery:  coincidental to the replacement of one of my
> > > batteries, the circuit breaker that controls the bilge pump tripped
> when
> > > ever the float switch activated.  I could reset the breaker and turn
> the
> > > switch on and the pump would work fine, but again every time the float
> > > switch activated in the auto position the breaker would trip again.  I
> > > assumed, wrongly, that the float switch itself was the culprit, and I
> > > replaced it.  No good, still trips.  Therefore I am at a loss to
figure
> out
> > > what is the exact cause.
> > > This is why I need your help, as I said, you know who you are!
> > >
> > > Sincerely,
> > > Herb Creech
> > > Cloud Chaser #606