[Johnson] Ranger fuses

[David C. Hallam]

Data are data but in this case the point is moot.  If the NEC says not to do
it and there is a possibility however small you could get hit in the pocket
book if you do, that trumps anything else.

David
KC2JD

-----Original Message-----
From: johnson-bounces at mailman.qth.net
[mailto:johnson-bounces at mailman.qth.net]On Behalf Of SBJohnston at aol.com
Sent: Sunday, February 19, 2006 4:54 PM
To: johnson at mailman.qth.net
Subject: Re: [Johnson] Ranger fuses


Kim writes:

> >But a short of the hot side to chassis would pop the hot
> >fuse, not the neutral one, wouldn't it?
> In a word--NO.  When you fuse both sides of the line, you're very
> likely to blow the neutral fuse, and leave the hot one intact.

I'm not seeing how this can be.  We have a hot line that is 120 volts from
both the neutral and the grounded chassis.  There is little or no voltage
differential between the neutral and the chassis.  Suppose something fails
to cause
the hot lead to short to the chassis.  Why would the neutral fuse blow??  If
anything, it would carry less current than usual, since some is going via
the
ground.  The hot lead, however, would definitely have high current.

OK, I'm going to set up an experiment to decide this point.  Stand-by a
moment...  OK, here's the set-up on the bench right now:

I've got a three wire cord plugged into an outlet that has been confirmed to
be wired correctly.  The hot and neutral wires of the cord are connected to
the end terminals of a dual fuse holder.  The other ends of the dual fuse
holder
go to my 60w trouble-light as a load.   There are two identical 1.5 amp
fuses
in the fuseholder.

I will now cause a short of the hot side of the lamp to the grounded wire of
the cord - this will simulate the short to chassis we are discussing - by
touching a clip-lead from the hot wire going to the lamp to the green wire
on the
cord.  Stand-by...

OK, the lamp went out the moment I touched the clip-lead to both of the
conductors.  When I inspected the fuses, I found the hot line fuse to be
blown.
The fuse in the neutral line is still good.   To eliminate the chance that
there
is something different about those two fuses, I'll get another pair from the
drawer and try again.  Stand-by...

OK, did it again, same results.  The hot fuse blew.

Steve  WD8DAS

sbjohnston at aol.com




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