Newsgroups: misc.consumers.house
From: Mark Fineman
Date: Wed, 10 Aug 2005 21:30:08 -0400
Local: Wed, Aug 10 2005 9:30 pm
Subject: Info to backup safety of aluminum wiring?

Does anyone know if using (and regularly testing) AFCI (Arc Fault
Circuit Interrupers) increases reliability aluminium wiring to
that of copper wiring when the current connection mechanisms are used?

***

A very good question. I'd love to know the answer too.

Thanks,
Harry

What about connection devices that are designed for larger aluminum
wiring ... but there happens to be a version of them that accepts
smaller wires? There's a whole bunch of such connectors shown in this
catalog: www.nsipolaris.com/pdf/connectors.pdf . I'm assuming some of
these would normally be found inside of a breaker panel to attach the
aluminum wire comming in from outside. As well as used to make
connections for larger aluminum wire that supplies ovens, etc.
However, a lot of these connectors accept 14 awg wire too, therefore,
would using such connectors be safer than using wirenuts. After all
the safety of wirenuts is not agreed upon by all, but how about the
safety of such connectors?

Thanks,
Harry

Bud wrote:
....
... I see no
evidence that the inspect-ny web site is other than an honest attept to
furnish unbiased information.

Perhaps, and wish it to be so...hope there isn't some legal-beagle
sitting in the background somewhere collecting anecdotal data in
preparation for a mass-mailing to enlist clients.

Maybe I'm just overly sensitive as I've a collection of some 10 or so
such mailings over the last year or two and there are at least three
local late night TV adds currently or recently fishing for
medical/pharamceutical/product liability participants...

Matt Whiting wrote:

Bud wrote:

Matt Whiting wrote:

Bud wrote:

SQLit wrote:


Your home and mine (also built in 1971) have lasted this long.
Chances are
they will last a lot more. This is my 3 home of this vintage.
Do you know anyone with a 1000 volt meggar? You will need to unplug
EVERYTHING for the test. The meggar can tell you if there is an
insulation
problem and to a point loose connections.

A megger only finds damaged insulation where there is a carbon path
to ground (or line-to-line). I think it would find a small
percentage of actual aluminum problems and no loose connections.
Disconnect GFCIs if you use one.

Bud--




If the problem is due to a loose connection or oxidation induced high
resistance, then a multimeter will certainly detect that on the
resistance measurement function.

(A multimeter is different from a megger.)

I don't think it is too practical to measure the junction resistance.
How do you connect to the wire that is on at least one side.
Tests have shown that wirenuts fail by the contact made not
wire-to-wire because of oxidation but through the steel spring. I
remember the resistance being about 2 ohms, not much. Not enough to
dim lights, no flicker. But the steel spring becomes a heating element
that destroys insulation and can ultimately cause a fire. 2 ohms may
be hard to find with a multimeter.


How is the steel spring any different for Al wire than for Cu wire? It's
heating is a function of the current through it or what it absorbs from
the wire, not a function of the type of metal connected to it. Heat is
generated by ohmic resistance, and that comes from corrosion between the
Aluminum wires or the wires and the wire nut spring, not the spring itself.


Matt

Steel has a high resistivity, which is why it is not used as a
conductor. The tests show the wires do not contact each other because of
oxide on the aluminum. The steel spring breaks through the oxide to make
contact with the aluminum conductors. This means all the current is
going through the spring. A CPSC report at
http://www.inspect-ny.com/aluminum/pl2p2.htm
shows a 2 volt drop across the wire nut at 17 amps. This is only about
0.1 ohm resistance but is a 34 watt heater. At this current level the
spring is red hot. This destroys the insulation on the wires and the
wire nut and can start a fire. But the voltage drop is low and constant
so lights are not dim and do not flicker. Later in the deterioration the
the connection can totally fail, possibly with arcing that generates a
lot more heat (more likely fire).

One wire nut that failed this way was the Ideal #65 twister which is
listed for aluminum/copper. Cleverly the plastic shell and the antioxide
paste in the wirenut are both combustible.

(The link above is part of a slide show that goes forward and back.)

http://www.inspect-ny.com/aluminum.htm links to this site and others
of interest.

Bud--

Harry Muscle wrote:

Newsgroups: misc.consumers.house
From: Mark Fineman
Date: Wed, 10 Aug 2005 21:30:08 -0400
Local: Wed, Aug 10 2005 9:30 pm
Subject: Info to backup safety of aluminum wiring?

Does anyone know if using (and regularly testing) AFCI (Arc Fault
Circuit Interrupers) increases reliability aluminium wiring to
that of copper wiring when the current connection mechanisms are used?

***

A very good question. I'd love to know the answer too.

Thanks,
Harry


Tests show that failure in wire nuts result from no contact between the
wires because of oxide on the aluminum. The steel spring breaks through
the oxide to make contact with the aluminum conductors. This means all
the current is going through the spring. A CPSC report at
http://www.inspect-ny.com/aluminum/pl2p2.htm
shows a 2 volt drop across the wire nut at 17 amps. This is only about
0.1 ohm resistance but is a 34 watt heater. At this current level the
spring is red hot. This destroys the insulation on the wires and the
wire nut and can start a fire. But the voltage drop is low and constant
so lights are not dim and do not flicker. Since there is no arc, there
is nothing for the AFCI to see.

Later in the deterioration the the connection can totally fail, possibly
with arcing that generates a lot more heat. Arcing here would be picked
up by an AFCI.

(The link above is part of a slide show that goes forward and back.)

http://www.inspect-ny.com/aluminum.htm links to this site and others
of interest.

Bud--

Note the split bolt connector is not UL aprroved for aluminum. I used the
2-SR in this application. Bulky even before taping, it required the use of
box extenders.
"Harry Muscle" wrote in message
oups.com...
What about connection devices that are designed for larger aluminum
wiring ... but there happens to be a version of them that accepts
smaller wires? There's a whole bunch of such connectors shown in this
catalog: www.nsipolaris.com/pdf/connectors.pdf . I'm assuming some of
these would normally be found inside of a breaker panel to attach the
aluminum wire comming in from outside. As well as used to make
connections for larger aluminum wire that supplies ovens, etc.
However, a lot of these connectors accept 14 awg wire too, therefore,
would using such connectors be safer than using wirenuts. After all
the safety of wirenuts is not agreed upon by all, but how about the
safety of such connectors?

Thanks,
Harry

Are split bolt connectors in general not UL approved for aluminum to
copper connections? Or just the ones in the link I've provided?

Thanks,
Harry

I just did a search on split bolt, aluminum, and UL, and it looks like
you must have been refering to just the link that I provided above,
since this page for example lists split bolt connectors designed for
joining aluminum to copper and it says that they are UL and CSA
certified:
http://www.gardnerbender.com/whats_n...onnectors.html . So
I've just answered my own question as to what you were refering too ...

Thanks,
Harry

P.S. Maybe I should start a new thread about this whole idea of using
larger connectors with aluminum wire ... since this is totally off
topic from where this thread started.

SQLit posted for all of us...
I don't top post - see either inline or at bottom.

Sanding a bare new conductor went out 20 years ago along with tape built up
stress cones.

tape build up stress cones?? What are they? Googled but no results...
--

Tekkie

Tekkie -

An 'old fashion' method of terminating high voltage cabling.

Regards,

Doug

"Tekkie®" wrote in message
...
SQLit posted for all of us...
I don't top post - see either inline or at bottom.

Sanding a bare new conductor went out 20 years ago along with tape built
up
stress cones.

tape build up stress cones?? What are they? Googled but no results...
--

Tekkie

Tests show that failure in wire nuts result from no contact between the
wires because of oxide on the aluminum. The steel spring breaks through
the oxide to make contact with the aluminum conductors. This means all the
current is going through the spring. A CPSC report at
http://www.inspect-ny.com/aluminum/pl2p2.htm
shows a 2 volt drop across the wire nut at 17 amps. This is only about 0.1
ohm resistance but is a 34 watt heater. At this current level the spring
is red hot. This destroys the insulation on the wires and the wire nut and
can start a fire. But the voltage drop is low and constant so lights are
not dim and do not flicker. Since there is no arc, there is nothing for
the AFCI to see.

Later in the deterioration the the connection can totally fail, possibly
with arcing that generates a lot more heat. Arcing here would be picked up
by an AFCI.

(The link above is part of a slide show that goes forward and back.)

http://www.inspect-ny.com/aluminum.htm links to this site and others of
interest.

Bud--
In northern Alaska where I am at, aluminum wire is rarely used. The extreme
temperatures cause too many problems with cold flow.

But the AFCI problem you bring up is interesting because according to the
Zlan site the inventor of the AFCI chip had to find a way to distinguish
good arcs like a light switch turning on and off from a bad arc. I wonder
if he analyzed all the possible combinations of aluminum to copper
connections.

the utility of afcis is somewhat dubious to begin with.

it is supposed to detect an arc, such as might happen when an extension
cord is damaged.

whether they actually do or not is not clear.

in any case they will not detect the heating that occurs on an aluminum
conenction that has started to oxidize.

No it won't. AFCIs detect arcs, and at fairly high current levels. The
oxidation that forms on aluminum connections reduces the current due to the
resistance of the connection, thats what causes the heat, and the fires.

"TokaMundo" wrote in message
...
On 16 Aug 2005 14:20:41 -0700, Gave us:

in any case they will not detect the heating that occurs on an aluminum
conenction that has started to oxidize.

It will if it gets "noisy" enough.

TokaMundo wrote:
On 16 Aug 2005 14:20:41 -0700, Gave us:


in any case they will not detect the heating that occurs on an aluminum
conenction that has started to oxidize.


It will if it gets "noisy" enough.


The manufacturers do not make it clear that AFCIs cannot detect series
arcs, such as those resulting from an oxidizing connection, until they
progress to a ground fault which draws at least thirty milliamperes. If
the arcing connection does not cause a ground fault the AFCI cannot
detect it and the heat it generates can kindle a fire. They can detect
a parallel arc such as when a screw penetrates a cable and causes a high
resistance arcing fault between the current carrying conductors. Such
parallel arcs are not that common.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

Member TPVFD wrote:

The manufacturers do not make it clear that AFCIs cannot detect series
arcs, such as those resulting from an oxidizing connection, until they
progress to a ground fault which draws at least thirty milliamperes. If
the arcing connection does not cause a ground fault the AFCI cannot
detect it and the heat it generates can kindle a fire. They can detect
a parallel arc such as when a screw penetrates a cable and causes a high
resistance arcing fault between the current carrying conductors. Such
parallel arcs are not that common.
--
Tom Horne

I keep forgetting that.

The 2005 NEC requires AFCIs with series AND parallel protection starting
1-1-2008. I don't know of any on the market now.

Bud--

Ralph Hertle wrote:
The AL metal its a superior conductor, and it is durable and easy
to work and install.

GOOD conductor? Yes, if properly installed. Durable, etc.? Same answer.
But silver and copper are better conductors of electricity.

--
If John McCain gets the 2008 Republican Presidential nomination,
my vote for President will be a write-in for Jiang Zemin.