Re: Carbon dioxide bike tyre inflation (was Re: That was dumb..)
- From: Jasper Janssen <jasper.janssen@xxxxxxxxx>
- Date: Fri, 13 Jun 2008 01:27:59 +0200
On Tue, 13 Nov 2007 03:23:57 GMT, mroberds@xxxxxxxxxxxxxxxx wrote:
Jasper Janssen <jasper@xxxxxxxxxxxx> wrote:
On Fri, 9 Nov 2007 04:40:07 +0000 (UTC), brian@xxxxxxxxxxxxxxxx (Brian
Kantor) wrote:
Yeah. I had this one set aside to respond to, apparently. I just noticed
this now.
Stranded is also more of a PITA to connect to receptacles etc. Most
low-end devices have terminal screws; one bends the end of the wire
into a hook, puts it under the screw, and tightens the screw. Stranded
tends to unstrand when you do this. Better receptacles work a bit like
a Eurostyle terminal strip - you stick the bare end of the wire straight
into a slot and tighten a screw, and a moving plate under the screw head
clamps the wire against a fixed plate. This works equally well for
solid or stranded.
Then there's the spring push-in style for solid wire only. This is good
for saving time at initial installation and ensuring recurring training
for the fire department later.
Haven't had that happen. Yet. Most of the switches I've bought over the
past decade or two were push-in and sockets wer eabout 50/50 between
push-in and simple scre terminal.
And of course, these days connecting one wire to the next is often done
with push-in thingies with 2/3/4/5/8 sockets.
The canonical house wiring in most of the USA is "romex", which is
plastic or fibre-jacketed with 3 solid #14 wires:
1.628 mm^2, ok. Fairly thinnish, that, by standards over here.
14 AWG is usually breakered or fused at 15 A, 12 AWG at 20 A. Some
jurisdictions outlaw 14 AWG; everything is 12 AWG and 20 A minimum.
..nl is fairly unique even in Europe in that we have standardised to an
amzing degree -- we use 2.5 mm^2 brown/blue/green-yellow and 1.5 mm^2
black wires, and nothing else, in standard house wiring.
Live/Neutral/Ground and Switched, respectively. The black is essentially
for switch-to-lightpoint wiring (and switch-to-switch, etc, when wiring a
single lighting point to multiple switches). And all that 2.5 mm^2 is
almost always breakered or fused at 16A, 10 in old houses, but it's still
2.5 so you can replace the fuses to 16A ones without trouble.
It even goes so far that the one thing that routinely takes more power
than a 16A 230V fuse can provide (that's 3.5 kW, after all), which is the
electric cooking thingy, when available, is wired either to a threephase
16A (using 5x 2.5) or, alternatively, is wired with 2 singlephase groups,
mechanically joined in the fusebox, and also using 5x 2.5mm^2.
Note that while the stove can usually be reconfigured as a 'two phase'
system, it generally still has common neutral, which means that if one of
the two neutral wires comes loose somewhere, you get 32A going through a
single 16A-rated wire. But at least everything's still a 16A fuse and 2.5
mm^2.
So that's where black/white internal wires come from. Extension and
device cords here usually have brown/blue inside the sheath, same as
the mains wiring.
One consistency I have noted: Houses and cars are different in the same
way in left- and right-pondia. Here, in your house, black is hot and
white is netural. In your car, red is hot and black is ground. In
Yurp, in your house, brown is hot and blue is neutral, and in your car,
red is hot and brown is ground.
Hm. Can't say I've noticed cars using anything but red/black. Certainly at
the battery, at least.
Another variation, pretty much out of favor these days, is a "split bus"
panel - there isn't really one "main" breaker. Basically this has a few
big 240 V breakers that have one side always hot unless there's a power
outage. Often there is one for the air conditioning (40 or 50 A), one
for the electric clothes dryer (30 A), and a "lighting main" (maybe 60
A). All of the 15 A and 20 A breakers for lights, receptacles, smaller
appliances, etc, go through the lighting main. The net effect is that
you have to shut off more than one breaker to kill the whole panel,
which is part of the reason why it fell out of favor.
It was the early 90s code revision here that required a breaker panel to
be switchable with no more than 2 motions. Since the early noughties we've
been required to do it in a single motion, and also required to have at
least 2 GFCIs for redundancy. Which means you need a main switch (that
goes between the meter and the GFCIs). Note, of course, that this only
applies to newly made or remade installations. You only have to comply
with what was current at the time you built the installation, except that
everything has to comply to the, 1967 I think it was, revision.
And presumably some form of powerco fuse protecting the meter?
That would be the fuse on the *primary* of the transformer. Local
distribution is three-phase at approximately 10-20 kV; the transformer
takes one phase of that and gives you 240 V center-tapped. There
usually isn't a fuse between the transformer secondary and the main
breaker.
Huh. We've got the 10 kV distribution as well, the powerco transformers
are, I think, on each end of a row of houses (at least those heavy-gauge
steel boxes don't look like telco or coax distro gear..), and then a 230V
3-phase groundcable (spliced into the streetcable in front of your door)
goes into your house. Then there's a 3-phase powerco main fuse at the base
of the meter cupboard, usually with just 1 of the fuse sockets populated,
then the meter board (a 330x220 socket with universal mounting holes) with
the meter sitting on it, and then you get into the section you own, going
through the main switch to multiple 30mA GFCIs, each of which breaks into
up to four 16A breakers.
Ah, I see where the difference comes from. You've got a main *breaker* at
the start of your own gear, we've got the powerco fuses just a little bit
earlier, but a main *switch* at the start of our own gear.
They outlawed house ground via the pipes a while back here, mainly
because the copper pipes of the waterco are being replaced by plastic,
which don't work so well as a ground pin.
One variation is to have a ground rod, usually right under the meter on
the outside of the house, and *also* a connection to the metallic water
pipes. This is partly to get additional earthy goodness from the water
pipes, and partly so the water pipes don't accidentally become
energized.
We do need to ground the internal water pipes, we're just not allowed to
bridge to the outside water pipes (water meters are nonconductive),
especially not using it as a source (if you will) of ground.
Wire goes into a sealed fusebox [...] goes into the meterboard [...]
and then comes out. From there on you own the wiring, before it it's
owned by the powerco and sealed.
The powercos around here play funny games. You don't own the
electricity until it's gone through the meter, but you own the wires all
the way up to the transformer. If a tree branch falls on the wires from
the pole to your house, you have to pay an electrician to fix them. The
Whut? Weird. I could almost see it working as long as you don't have
buried cables. That explains why we don't have that sort of game, I
suppose.
The actual fusebox these days is often a 330x220 box containing 2
DIN-size rails for 12 units of 18 mm wide each.
Our breaker panels are standardized by the miracle of capitalism; that
is to say that there are N different and almost-incompatible standards.
Wise persons install General Electric, Square D, or maybe Cutler-Hammer
breaker panels, because there is some level of assurance that you will
still be able to buy breakers for them next year and 30 years from now.
Ask anybody with a Federal Pacific Electric or Zinsco breaker panel how
much *fun* it is to add a circuit (if, as in the case of the FPE, their
house hasn't burned down first).
I've seen a breaker panel (of one brand or another) being manufactured on
'How It's Made', it appeared to have the general layout of one big ass
master breaker at the top (rather than the bottom, which would seem to be
the obvious place for it, but whatever), then the two phases going to two
busbars, each of which alternated placing a piece of metal in the center,
onto which you could click breakers on both sides, single or double phase
depending on the width, plus ground and neutral bars along the sides, to
get a complete circuit going off each breaker.
It seemed fairly easy to expand, that one, but extremely dangerous to do
so without switching off the master breaker.
Our older units were less clicky, but even they were already more
standardised. Olden days, the 220x110/220/330 mm cases would be the main
units, and you would be able to take one of the small ones with a main
switch, and a medium one with 5 fuses & switches, or a small one with 2
fuses & switches, etc, and screw them to the baseboard in a reasonable
resemblance of fitting together.
These days, as I said, they use the DIN rail to construct them. Each
breaker/switch/doorbell transformer/gfci/socket-for-the-adsl-modem clicks
onto the din rail, and will have inputs with screw terminals at the bottom
and outputs at the top, and you proceed to wire the whole thing up nicely.
You can use busbar 'combs' to wire up a whole nest of breakers next to
eachother but insulated wire will work at least as well, and lead to a
safe(-ish) interior.
The latest innovation is euro-din rails which have little sockets in them,
so that you can put on standard wired components or clicky components with
pins for that socket. Naturally *that* isn't standardised. But you can
always elaborate with a standard wired breaker, or even (as in our house)
add an extra box.
AFAIK there is no such think as a ring main in the US. Strictly star,
but each leg of the star might have several receptacles or lights on it.
Ring mains aren't allowed in .nl either. I think they were mainly a
british wartime or possibly Reconstruction invention.
[2] My fire plan is to get my my own personal and valuable ass out of
the house first, sound the alarm, then see that other people and
critters are out to the extent of my ability. Then I will go shut
off the gas and pull the meter while I'm waiting for the pros. I'll
gladly deal with a pissed-off powerco if it means I can hand the
meter to the first-responding engine so they can get started sooner.
My house was on fire doesn't constitute the sort of emergency where the
powerco allows you to do it?
Jasper
.
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