Text 9982, 65 rader
Skriven 2010-08-16 08:37:34 av Robert Bashe (2:2448/44)
   Kommentar till text 9975 av Michiel van der Vlist (2:280/5555)
Ärende: Just Curious
====================
Michiel van der Vlist wrote to Robert Bashe on Sunday August 15 2010 at 18:44:

RB>> Germany, all the circuit breakers are 16A - that, however, doesn't
RB>> mean a single socket is 16A, since the breakers (we don't use fuses
RB>> here except for the main lines

MV> In Dutch they are both covered by the term "zekering". "Sicherung" in
MV> German?

Yes, a (Schmelz)Sicherung is a fuse that burns out once and cannot be reset.
Then there are the Leitungsschutzschalter, the "breakers" I referred to. When
they trip, a button in the center pops out and you have to push it back in to
reset the circuit.

MV> Both are allowed, although in new installations yoy will mostly find
MV> circuit breakers. I prefer the one that we cal "smeltzekering".

The Germans call that a "Schmelzsicherung" (melting fuse).

MV> The one time fuse where a wire melts when it is overloaded. Unless you
MV> make shorts very often they are cheaper. But that is not the main
MV> reason for my preference. I judge them to be more reliable. A circuit
MV> breaker (Stotz) is a fairly complicated electromechanical device. It
MV> can fail, especially after having been activated many times. The old
MV> fuse with the melting wire is almost infallible.

Maybe. We don't have overloads very often here - I can only remember maybe a
dozen times since we moved in in 1985 - and so I can't really say. I don't
think we've ever had one of the fuses burn out, just the breakers tripped.

As for the economics, you're of course right (although I don't know if fuses
are allowed on in-house 16A circuits in the newest building codes in Germany,
the regulations are pretty complex and not always understandable for a
layperson). However, if you've ever had a fuse blow on a Sunday night, when you
can't buy a replacement and just by chance have no spares at hand, you start to
appreciate the breakers more. And of course the breakers have the advantage
that people can't abuse them like they sometimes do fuses - wrapping a
burnt-out fuse with aluminum foil, or shorting the socket with a (US) penny are
famous ways people have used to restore power - and often tu burn down their
house.

RB>> - the ones from the power lines in the street to the internal lines
RB>> in the house - and they're higher capacity)

MV> Some power companies use circuit breakers for those too in new
MV> installations. (resetteable by the customer) Others take my POV... (In
MV> a sealed box, not replaceable by the customer).

Our main line fuses can be replaced by the customer - replacements in the
building supply markets - but as I say, we've never had the need to do this.
Only the breakers have ever tripped here.

We also have what they call FI switches here, which trip and interrupt the
power when a certain small amperage (I believe 50-100 mA) drains to ground, as
when a grounded person touches a live line or the insulation in an appliance is
no longer completely adequate (but still doesn't short out). They are required
for all new buildings (and were required in 1985, when we remodeled our house,
so this is nothing new). The original purpose was to keep cows who licked
electric lines from being electrocuted on farms, but they are now ubiquitous in
private homes as well, the purpose being to prevent accidental electrocution.

Cheers, Bob

--- GoldED+/W32 1.1.5-0613
 * Origin: Jabberwocky System - 02363-56073 ISDN/V34 (2:2448/44)