knackered bottom bracket

On 2016-08-13 23:07, John B. wrote:
On Sat, 13 Aug 2016 13:49:14 -0400, Radey Shouman
wrote:

John B. writes:

On Fri, 12 Aug 2016 14:48:53 +0000 (UTC), David Scheidt
wrote:

John B. wrote:
:On Thu, 11 Aug 2016 16:17:05 -0400, Radey Shouman
wrote:

:John B. writes:
:
: On Wed, 10 Aug 2016 11:06:07 -0400, Radey Shouman
: wrote:

------------%---------

:High amperage shouldn't be a big problem for a bicycle dynamo.
:
:During the 70s Al was used for house wiring in the US, leading to
:problems when unsuitable connectors gradually increased in resistance
:and heated up. There is still quite a lot of Al wiring about, but I
:guess the really bad jobs have all been repaired or burned down.

uring the '70's the price of copper went to an extremely high price
:and thus it became almost unfeasible to build a house with copper,
:using the U.S. low voltage system. And of course, that cheaper
:Aluminum wiring is still in a lot of walls. The problem isn't in the
:initial wire it is what came later. The extension cord plugged into a
:single receptacle so that the fridge, microwave, ice maker, dishwasher
:and a second microwave (for popcorn) can all be plugged in :-)

No, the problem is the aluminum wire. Or rather, the improper
termination of the aluminum wire. Aluminum expands at different rates
than copper, so the connections can come loose over time. Loose
connections lead to heat. Aluminum wire is also more brittle, and can
be damaged when someone works on it, which leads to higher resistance
and heat. Additionally, aluminum wire can oxidize, which also leads to
higher resistance connections. All that heat can lead to a nice fire,
even without overload.

Well, yes. Except that every professional electrician I ever worked
with will, when something doesn't work quite right, immediately
tighten all the connections and I'm going right up to the 4,000 volt
connections to the "Pole Pig". And you know? Quite often that fixes
the problem. Even with copper to copper connections :-)



Aluminun is still widely used for wire, but mostly for large gauge
stuff, which suffers less from those problems. And it's supposede to
be treated with anti-corrision goop.

Nope. The coefficient of expansion doesn't care if it is Big Aluminum
or Little Aluminum it is the same. :-)

(And, properly protected wiring will trip the
breaker before the overload can start a fire. Unless, of course, some
moron has replaced the proper breaker with an oversized one, like they
did in my house. 30A breakers on 14 gauge wire! That got fixed
before we moved in.)

From the houses we have rented from time to time over the years my
guess is that "putting a penny" in the fuse is an almost universal
practice. Over here there are still a few of the old "knife switch and
fuse wire" entrance connections on old houses and if you replace the
old fashioned lead fuse wire with copper you will never have another
blown fuse :-)

I haven't seen an actual household fuse box in a US rental house for 45
years or so. Those insurance companies you were lecturing about might
object.

I haven't even seen a U.S. house in 40, or more, years :-)

I did check the Electrical code and generally it does refer to fuses
so I guess in some instances they are still legal, but certainly I
would think it justified for an insurance to shield the fools from any
possible contact with danger so I wouldn't find it surprising for a
home box to contain only little plastic handles marked 10, 15 and 20
:-)

I've never seen a house wired with aluminum but I would guess the real
problem might be in the circuit breakers. A pretty standard size
breaker for #12 copper wire would be a 20 amp breaker, which wired
with aluminum #12 wire would be about 30% oversize.

I lived in a newly built house with Al wiring in 74-75, and again in an
apartment building with Al wiring until four years ago. In neither case
could you tell without actually looking at the wires.

You make it sound as though gangs of rogue electricians, high on black
market "acid flux", just decided to install some Al wire that fell off a
truck. In actual fact the wire was manufactured for house wiring, which
was done according to the code at the time. Larger diameter Al wire was
required compared to Cu in equivalent service. Initially all worked
well, but, as Mr. Scheidt says, there was an unforeseen increase in
wiring connection resistance, sometimes ending in fire.

Of course house wiring was manufactured for house wiring :-) And, as
far as I know it still is. And it is made to exactly the same codes
and standards as copper wire. You can, for example, buy #12 copper
wire and you can buy #12 aluminum wire.


You need larger gauge aluminum versus copper for same current carrying
capability.


... And you can also buy aluminum
to copper connectors.

I worked at one Air Base where all the "secondary" wire was aluminum,
made up to any copper connection with the proper aluminum to copper
connectors and there was no more problems with loose connections in
the Aluminum wire than there was with any other wire.

The old wives tale that aluminum, simply because it is aluminum
somehow gets loose and copper simply doesn't seems to be just that.


Let's put this on a more realistic footing.

https://www.nachi.org/aluminum-wiring.htm

--
Regards, Joerg

http://www.analogconsultants.com/

John B. wrote:
:
:Aluminun is still widely used for wire, but mostly for large gauge
:stuff, which suffers less from those problems. And it's supposede to
:be treated with anti-corrision goop.

:Nope. The coefficient of expansion doesn't care if it is Big Aluminum
r Little Aluminum it is the same. :-)

Larger conductors have less of the problems because they're installed
to equipment designed for aluminum conductors, larger conductors are
operated at lower temperatures, and because their devices are ****ed
with less often.


:I've never seen a house wired with aluminum but I would guess the real
roblem might be in the circuit breakers. A pretty standard size

No. The problems are at splices, and at device termination, for the
reasons listed up the thread.



--
sig 109