Re: just an idle question


"Who Me?" <hitchhiker@xxxxxxxxxx> wrote in message
news:kg%5k.3504$cW3.1764@xxxxxxxxxxxxxxxxxxxxxxx

"the fly" <tsetse51@xxxxxxxxxx> wrote

A fuse on the grounded + side of the circuit won't protect against
short
circuits on the - side.


Utterly ridiculous. Of course it would.
It takes a complete circuit for current to flow; doesn't make any
difference
WHERE you open it.

Ridiculous, yourself.

This is a hypothetical discussion, since it is virtually never done

change "virtually" to simply "never"

but............

A fuse that removes the common/ground side of a circuit or circuits
completely from the power supply certainly would stop the current
flow.......completely. You cannot "short circuit" something that has no
current flowing in it because the voltage potential is the same at every
place in the "circuit".


Unless you have a wire chafed somewhere, in which case your ground
is now reconnected and you have current flow. That's why we don't
fuse common/grounds, period, in ANY power system.

In the case of DC vehicle systems, a very effective and recommended way to
prevent damage from an accidental short is to disconnect the ground lead
from the battery.......as if there was a fuse there that has operated.


No, that is not true. The recommended way to prevent damage from
an accidental short is to disconnect BOTH battery terminals and REMOVE
the battery from the system.

Having a live battery in there will not prevent a short - all it takes is
absently setting a bolt on top of the tank with the seat removed, and
bumping the bike to have the bolt fall and wedge in between the battery
negative terminal and ground while you have the wiring hanging out
elsewhere on the bike.

Or for more fun, drop a screwdriver in there and short the battery
out alltogether.

Doesn't apply to earth ground systems like commercial AC because "you"
have
no control over the power supply and it is always connected to ground.


?!?!

AND.....back to the original premise.......a fuse doesn't "protect"
against
short circuits regardless of where it is placed. It protects the wiring
and
power supply from releasing THEIR smoke.....along with the component that
has already failed. A properly sized fuse WILL perform that function quite
nicely, regardless of where it is placed in the circuit.


The PRIMARY purpose of a fuse is safety of human life. The bike maker
doesen't give much of a crap if the wiring or component shorts and melts.
Wires are pretty easy to replace. What they DO care about is if the
component
shorts then gets so hot it melts and starts a fire. If that were to happen
while you
were flying down the road you might wreck and that's not very good for
sales,
you see. The secondary function is to protect the wiring and/or components.

And placing the fuse in the ground side of the circuit isn't going to
protect
anything since any component that has a supply lead going to it that fails,
can
potentially fail in a manner where the internal electric conductors short
against the chassis.

Ted


.

Relevant Pages

  • Re: Bad Idea: Put 9V Flasher LED on top of 9V Battery??
    ... "attach it to the car battery" is a little scary. ... The right place to tie in is at the car's fuse block. ... You'll want to find a circuit with a small-value fuse ...
    (sci.electronics.basics)
  • Re: GFI for a fuse box...
    ... things on that breaker. ... In your case the bathrooms I suppose might be on the same fuse as the ... work well for these too if the four receptacles you want to protect ... are either on the same circuit, or on different circuits that don't ...
    (alt.home.repair)
  • Re: Is it worth updating the electrical system?
    ... might put too much of a strain on the circuit and cause it to blow a fuse. ... you upgrade a kitchen, bathroom, bedroom or garage conversion and more. ... At least if you hire an electrician and there are not too many branch ...
    (alt.home.repair)
  • Re: Electrical pt.2
    ... wouldn't want a fan burning a fuse then letting the rest of the ... or would it be better to use a nearby 120V circuit? ... The ground wire for the run appears to be 12 guage or so, ... This caused the transformer to burn out since the ...
    (sci.electronics.basics)
  • Re: Is it worth updating the electrical system?
    ... Turns out to be on a separate circuit from the air conditioner upstairs ... it got me thinking about this old fuse ... At least if you hire an electrician and there are not too many branch ... He said the fuse panel has three 30 amp fuses that are all oversized. ...
    (alt.home.repair)