Sujet : Re: electrical deaths
De : robin_listas (at) *nospam* es.invalid (Carlos E.R.)
Groupes : sci.electronics.designDate : 02. Dec 2024, 22:44:53
Autres entêtes
Message-ID : <lbm12lx923.ln2@Telcontar.valinor>
References : 1 2 3 4 5
User-Agent : Mozilla Thunderbird
On 2024-12-02 22:17, Joe Gwinn wrote:
On Mon, 2 Dec 2024 11:35:41 -0800, Joerg <news@analogconsultants.com>
wrote:
On 12/1/24 9:59 AM, Joe Gwinn wrote:
On Sat, 30 Nov 2024 14:24:11 -0800, Joerg <news@analogconsultants.com>
wrote:
...
Polarization can save the day with toasters and similar appliances. Then
you can make sure that neutral comes in at the top end of the meanders.
In the US, 99+ percent of cases will not have line and neutral reversed.
I think that the 99+ percent is quite optimistic, especially on older
buildings. Back when I was an apartment-dweller, ran into all manner
of trouble, to the point that one of the first things I did in a new
apartment, was to turn the power off and opened all electric boxes,
and straighten out the "carpenter wiring", much of this being
dangerous.
War Story One: In the 1970s in Washington, DC, my boss was having
considerable problems with the lights in his newish house in the
suburbs. For instance, when he turned one light on, an unrelated
light would go off. I said it sounded like some kind of grounding
problem. Eventually he invited me to dinner in his house, and bring
your voltmeter. Which I did. It turned out that the solid copper
wires at every electrical device (wall switch, outlet, light, et al)
were loose - the electrician (or his assistant had forgotten to
tighten all the terminal screws down. (Stranded wire was not used
then.) So boss called the builder to have all those neglected
terminal screws tightened properly. He was lucky that there wasn't a
fire.
War Story Two. Ten years later, in Baltimore, MD, some friends
complained that their kitchen light (in the center of the ceiling)
flickered, and mentioned that when they used the sink in the washroom
off the kitchen, sparks fell from underneath that sink. I didn't
believe them at first, but they persisted. It turned out that the
building (which was quite old) still had some old knob-and-tube
wiring. The plumbers had recently replaced the drain pipe from the
bathroom above the washroom with a new copper pipe, and had barged
through the existing knob-and-tube wiring, breaking the return path,
but accidentally making the drain pipe live. The current made it from
the copper drain pipe to the existing cast iron drain through the
hardware on the washroom sink. Stopgap was to firmly ground the drain
pipe. I assume the owner of the building had words with the plumber,
and got an electrician. Anyway, nobody was hurt, and nothing burnt
down.
I have many such stories, but this will do for now.
And I bet that Europe also has its heart-stopping stories.
Not a dangerous one.
The lights in the garden in my father beach place were connected, the neutral to one current limiter, the live to another one. The result was weird: the residual-current device (RCD or RCCB or GFCI) of the house (here the entire house must be protected by one) triggered at half past six in the morning, every morning.
The electrician was baffled. He found out that the station switched the transformer one notch at that hour, but why would that cause the GFCI to trigger nobody could imagine. Finally he found the crossover, and the thing stopped happening.
On that same place, a cable entered a certain tube with one colour and exited a different colour.
Turned out that the installation had been done by three different electricians, each not knowing what the previous one intended or did.
Joe Gwinn
PS: I do prefer the Euro-style closed terminals that work for
stranded and solid wire. They are allowed in the US, but not all that
common outside of industrial sites. One big advantage is that they
take far less volume than wire-nuts and the like.
.<https://en.wikipedia.org/wiki/Knob-and-tube_wiring>
Oh! I had seen the article time ago, I had forgotten.
-- Cheers, Carlos.