w_tom wrote:
On Aug 27, 11:33 am, bud-- wrote:
The wirenut spring is not intended to be a major current carrying element.

Which is why wirenuts do not have that metallic spring inside? Wire
nuts using only grooves in the plastic cannot be used. Wire nut uses
a metallic spring sufficient sized to conduct major currents.
..
One of w_'s special skills is not knowing what his sources say. From
w_'s link":
http://www.inspect-ny.com/aluminum/pl2p8.htm
"27. That is exactly what has happened here. All of the current is
passing through only a few segments of the spring and those parts of the
spring become red hot."

From elsewhere in the same series:
"17. The characteristic heating in a band around the connector shows us
where the heat is being generated. In all of those failures shown, from
both lab and homes, the heat is generated by current flowing in the
connector spring. Here, all of the current is passing from wire-to-wire
through sections of the steel spring."

"24. Measurements on newly made aluminum-wired twist-on splices show
that most of the current flows through sections of the steel spring.
More than 60% typically for an aluminum connection, but less than 10%
for an all-copper connection. There is a basic difference in behavior
with aluminum wire."

"The key observation is that with this type of aluminum to copper wire
splice, most of the current flows through the spring in the connector.
In the design of twist-on wire connectors *the purpose of the spring is
to maintain tension on the spliced wires, not to conduct electricity
itself*."

Wirenuts on aluminum wire can fail *because* the spring "conduct major
currents."

In addition to not being able to understand his sources, poor w_
apparently doesn’t know that steel, which the spring is made of, is not
a particularly good conductor.
..
Bud is not posting to provide useful facts. Bud is my troll who
routinely posts only to insult.
..
Poor w_ gets so upset when someone exposes his misinformation.
..
And then copper wires also must be
sufficiently twisted so that wire without a wire nut will also safely
conduct that current.
..
Still missing - requirements from any manufacturer, or UL or the NEC
that wires be twisted.
..
Spring must be
sufficiently sized so that this fire cannot happen:
http://www.inspect-ny.com/aluminum/pl2p8.htm
..
How can anyone be stupid enough to completely miss what his source says.
The overheating was *because* the spring was forced to be a major
conductor. The spring was not the problem. Lack of aluminum wire-to-wire
contact was.
..
Bud knows this. But a troll always seeks reasons to post insults.
..
Poor w_. Always certain, sometimes right. But not often.

--
bud--