[BC] Fused plugs - was Hot and grounded chassis

[nakayle@gmail.com]

 Jeff, If you have 120/240V service in that house you definitely
should nothave fuses in the neutral- if a neutral fuse opens then the
240V will divide
in inversely to the load- so that stuff on the less loaded side will see far
more than the normal 120V- like maybe 180V or more- this could blow out
stuff and even start a fire.

 About all houses with fused neutrals had 2-wire 110V service originally and
this fuse should have been removed with they were converted to 120/240V.
It is almost certain that your neutral is grounded at the transformer as
this has been a NEC requirement almost for ever.  The secondary is grounded
for two reasons- if the secondary were truly floating then even a slight
leakage from the primary (like through the transformer oil) would raise the
voltage (to ground) in the house to very high levels- maybe thousands of
volts- since there would be nothing to 'load' it down.  By grounding the
secondary this leakage current is grounded out or if it's a large leakage,
it blows the transformer's primary fuse.  The second reason the secondary is
grounded is to give lightning hits and spikes a ground path.

  - Nat Kayle

On 8/11/06, Jeff Johnson <jjohnson at goodnews.net> wrote:
>
> I own an 1880 building and an 1890's building. One of them still has some
> of the knob and tube which I have retained. It is still legal,
> incidentally, as long as it is fused at 15A being #14GA.  Friends have a
> building with knob and tube fused on both legs. There was, seemingly, no
> differention between hot and ground. It appears that 19th century house
> wiring was considered essentially 'floating'. I've seen switches in the
> common leg. That is OK in a sense when there is no formal ground
> reference,
> then, however, both sides are 'hot'. The house I mentioned with fuses on
> both sides has been rewired so much through the decades that I decided not
> to remove the fuses now connecting to the common bus of the (modern)
> breaker panel, as some of the switches still are on the cold side. It is a
> four story brick Victorian and a complete rewiring would cost more in
> replastering (I mean lath and horsehair plaster) than the electrical. I've
> told my friends that socket shells can be hot, so be careful.
>
> One Christmas party, all of the Christmas lights suddenly brightened. We
> did not know if it was the moment of Jesus' birth or ... ?? Turned out a
> fuse blew on one of the common legs putting the lights in series across
> 220
> with the other leg which was more heavily loaded by warmers on the buffet.
> The food was getting colder and the lights of the Saviour were flaring
> like
> the Star of the East and burning out. Freaked everyone, but a new fuse
> cured the problem.
>
> Jeff.Johnson at goodnews.net,CSRE
> RFPROOF.COM
>
> >I don't know either, but the house I grew up in was built in the 30s or
> >40s.  Also, the house I have now was built in the 1890's with
> >electricity added later.  There is evidence of knob and tube wiring, but
> >that was all removed by the time I bought the house in the 1976.
> >However, all the outlets were equal sized slots until I changed them.
> >
> >Gordon S. Carter, CPBE, CBNT
> >Chief Engineer
> >WFMT and The Radio Network
>
>
>