Really? Then according to your expert theory, my restaurant ought to have burned
down long ago.

http://www.neon-john.com/images/Wiring_overload.jpg

That photo is of what is left of the original 40s vintage 3 phase indoor meter
box.
Long since bypassed as a meter base, it still passed up to 300 amps at times.
That's
either #4 or #2 cloth covered, rubber insulated wire in the service entrance.
#4, I
think. It's obviously been hot enough to slag the rubber insulation but somehow
it
just keeps on truckin'. Of course, the wire is in rigid conduit and despite your
declaration to the contrary, steel still doesn't burn very well.

That conduit has been too hot to touch on occasion. I monitored it closely in
the
summer time. I'd have loved to have replaced it but the city says that I can't
do my
own electrical work and I'm not about to pay someone else to do it so... It's
been
there since the 40s and it'll probably be there until the building is torn down.

Perhaps you ought to look at the other post I made in this thread about how to
compute irradiative losses from a hot object. The concept is simple enough for
someone even of your caliber to understand.

Maybe you ought to get your code book out too. At various places it discusses
the
losses involved in various wire and cable temperature rises.

John

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Nothing in life is to be feared. It is only to be understood. -Marie Curie

Posted by Floyd L. Davidson on January 24, 2008, 10:54 pm

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>On Thu, 24 Jan 2008 17:19:01 -0900, floyd@apaflo.com (Floyd L. Davidson) wrote:

>>>He's not talking resistance -- he's talking about a short circuit. Please be

>>>sure of your terms before you call someone else names, and insult them.

>>>

>>>I've known of houses with broken down insulation in the lead in wire,

>>>creating a high energy bill. So, it's a real condition.

>>More total bullshit. That would burn the house down

>>long before you got the bill. As Mike said, if the

>>connection where so hot it was shining brightly in the

>>daylight... and indeed that is what it would take to

>>create a high energy bill, and it *would* set fire to

>>something.

>Really? Then according to your expert theory, my restaurant ought to have

burned

>down long ago.

>http://www.neon-john.com/images/Wiring_overload.jpg

Sure sonny. Now tell us just how much electricity that
mess actually used. Nothing there used up enough power
to cost more than 20 cents a month!

>Perhaps you ought to look at the other post I made in this thread about how to

>compute irradiative losses from a hot object. The concept is simple enough for

>someone even of your caliber to understand.

But not so simple that you quite understand it, eh?

>Maybe you ought to get your code book out too. At various places it discusses

the

>losses involved in various wire and cable temperature rises.

Another item you don't seem to quite understand yet.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com

Posted by Neon John on January 25, 2008, 1:28 am

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On Thu, 24 Jan 2008 18:54:22 -0900, floyd@apaflo.com (Floyd L. Davidson) wrote:

>>Really? Then according to your expert theory, my restaurant ought to have

burned

>>down long ago.

>>http://www.neon-john.com/images/Wiring_overload.jpg

>Sure sonny. Now tell us just how much electricity that

>mess actually used. Nothing there used up enough power

>to cost more than 20 cents a month!

My, such charm and wit.

OK, well "Pop", let's go back to that Stefan-Boltzmann calculator and do a little
math.

The conduit between the meter base and that box is about 40 ft of 2" rigid
conduit.
It runs exposed so we don't need to worry about conduction losses, only
radiative and
convective.

Forty feet of 2" conduit is 21 sq ft. Let's use 80 deg C for the conduit because
that is just about "too hot to touch" and 20 deg ambient. We'll use 0.95
emissivity
since the conduit is old and dirty and pretty close to a black body. That comes
out
to 858 watts. In that temperature range, convective losses will be about twice
those
of radiative losses so we'll figure 1716 watts there for a total of 2,574 watts.

My restaurant was open about 70 hours a week and the load remained fairly
constant
throughout the day so 2,574watts * 70hours * 4weeks = 721kWh. At $0.09 per kWh,
that's $64.89 per month. A bit more than 20 cents a month, wouldn't you say?
Chop
the calculated amount in half or even by 10 if you like. Doesn't matter, you're
still
wrong by an order of magnitude.

And I didn't even try to account for the cost of air conditioning that heat to
the
outside, a necessary task since all but a couple of feet of the conduit runs in
air
conditioned spaces.

Sanity check: Using the 0.000292 ohms per foot from
http://www.epanorama.net/documents/wiring/wire_resistance.html for #4 wire and
120
feet of wire (three phase) and 300 amps, that works out to 3,154 watts. At 250
amps,
2,190 watts. That brackets my calculated values nicely. Sanity check passes.

Feel free to plug your own numbers and see what you get. It'll be > 20 cents.

You remind me of that old saying: "Those who ignore the math are doomed to look
like
idiots."

John

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Unable to locate Coffee -- Operator Halted!

Posted by Solar Flare on January 25, 2008, 8:37 am

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I guess you can't get a high bill from a 3000 watt heater locked on
24/7 then?

After all a 3000 watt heater doesn't glow so it can't produce the

3kW x 24hr. x 30days x $0.10/kWh = $216 extra on your bill.

I guess he meant a $5000 electric bill before you can have a fire.

> On Thu, 24 Jan 2008 18:54:22 -0900, floyd@apaflo.com (Floyd L.

> Davidson) wrote:

>>>Really? Then according to your expert theory, my restaurant ought

>>>to have burned

>>>down long ago.

>>>http://www.neon-john.com/images/Wiring_overload.jpg

>>Sure sonny. Now tell us just how much electricity that

>>mess actually used. Nothing there used up enough power

>>to cost more than 20 cents a month!

> My, such charm and wit.

> OK, well "Pop", let's go back to that Stefan-Boltzmann calculator

> and do a little

> math.

> The conduit between the meter base and that box is about 40 ft of 2"

> rigid conduit.

> It runs exposed so we don't need to worry about conduction losses,

> only radiative and

> convective.

> Forty feet of 2" conduit is 21 sq ft. Let's use 80 deg C for the

> conduit because

> that is just about "too hot to touch" and 20 deg ambient. We'll use

> 0.95 emissivity

> since the conduit is old and dirty and pretty close to a black body.

> That comes out

> to 858 watts. In that temperature range, convective losses will be

> about twice those

> of radiative losses so we'll figure 1716 watts there for a total of

> 2,574 watts.

> My restaurant was open about 70 hours a week and the load remained

> fairly constant

> throughout the day so 2,574watts * 70hours * 4weeks = 721kWh. At

> $0.09 per kWh,

> that's $64.89 per month. A bit more than 20 cents a month, wouldn't

> you say? Chop

> the calculated amount in half or even by 10 if you like. Doesn't

> matter, you're still

> wrong by an order of magnitude.

> And I didn't even try to account for the cost of air conditioning

> that heat to the

> outside, a necessary task since all but a couple of feet of the

> conduit runs in air

> conditioned spaces.

> Sanity check: Using the 0.000292 ohms per foot from

> http://www.epanorama.net/documents/wiring/wire_resistance.html for

> #4 wire and 120

> feet of wire (three phase) and 300 amps, that works out to 3,154

> watts. At 250 amps,

> 2,190 watts. That brackets my calculated values nicely. Sanity

> check passes.

> Feel free to plug your own numbers and see what you get. It'll be >

> 20 cents.

> You remind me of that old saying: "Those who ignore the math are

> doomed to look like

> idiots."

> John

> --

> John De Armond

> See my website for my current email address

> http://www.neon-john.com

> http://www.johndearmond.com <-- best little blog on the net!

> Tellico Plains, Occupied TN

> Unable to locate Coffee -- Operator Halted!

Posted by Floyd L. Davidson on January 25, 2008, 1:35 pm

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>On Thu, 24 Jan 2008 18:54:22 -0900, floyd@apaflo.com (Floyd L. Davidson) wrote:

>>>Really? Then according to your expert theory, my restaurant ought to have

burned

>>>down long ago.

>>>http://www.neon-john.com/images/Wiring_overload.jpg

>>Sure sonny. Now tell us just how much electricity that

>>mess actually used. Nothing there used up enough power

>>to cost more than 20 cents a month!

>My, such charm and wit.

>OK, well "Pop", let's go back to that Stefan-Boltzmann calculator and do a

little

>math.

>The conduit between the meter base and that box is about 40 ft of 2" rigid

conduit.

Learn to read and respond to the topic of discussion.

You are talking about a 40 foot run of cable. Nobody
else is.

The discussion was about what happens with a single
connection inside that junciton box. If it is a high
resistance sufficient to cause even a slight reduction
in the power available to other loads on the circuit, it
is going to get hot and either burn through and become
an open, or start a fire.

You've compared grapefruit and oranges, but we were
talking about apples.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com

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