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Q: Electrical ( Answered 4 out of 5 stars,   1 Comment )
Subject: Electrical
Category: Science > Instruments and Methods
Asked by: jelem2000-ga
List Price: $40.00
Posted: 21 Nov 2005 11:28 PST
Expires: 21 Dec 2005 11:28 PST
Question ID: 595858
In an upcoming cout case the police got a seach warrant by using a
thermal imaging camera (Raytheon Palmir 250)They said that the
electrical wire going to the house was anormaly hot. There was 15
lamps on in the house.Each 1000watts sodium high pressure.The wire
going to the house is about 300ft long,
it is new and is rated 400amps. I do not beleive that 15000watt would
generate enough heat in a 400amps wire so that it would be visible on
that camera. I also would like to know how many amps would go through
the same wire if all the electrical appliances were in use in the
house instead of the lamps.Of how many degree would that increase the
temperature of that wire.
Thank you
Subject: Re: Electrical
Answered By: redhoss-ga on 21 Nov 2005 13:36 PST
Rated:4 out of 5 stars
Hello jelem2000, I think your reasoning is sound and that you have a
very legitimate complaint. I have found information that you can use
to prove your point. First we need to know what wire size is used in a
400 amp service. This is found here:

Look on page 2 at the chart titled "Customer Wire Sizes". I will
assume you have copper wire in your service. The two "hot" wires would
be 500kcmil. Now we need to know what the temperature rise would be
for the amount of current as stated in your question. This is found

Look on page 11 at the chart titled "Sheath Temperature Rise Type MI
Single Conductor 600 Volt Free Air Conditions". Your wire size
(500kcmil) is shown at the far right. It is the largest conductor
shown. I will assume that you are operating the lights at 120 volts.
This is the worst case. If you are operating at 220 volts, the current
would be 1/2 what we are going to calculate. So, for 120 volt the
amperage would be 15,000 watts/120 volts = 125 amps. Assuming that all
the lights are powered by the same conductor, which is probably not
the case and is the worst case. Reading from the chart that should
produce a temperature rise of 5 degrees centigrade or 9 degrees
farenheit. If you were operating all of your electrical appliances,
lets say that you might be drawing 300 amps or 150 amps per conductor.
Again, from the chart that should produce a temperature rise of 7.5
degrees centigrade or 13.5 degrees farenheit. So, you can see what all
of this leads to. It would be absolutely impossible to tell from the
temperature of your service wires what appliances you are operating in
your home. Also, I don't care how accurate the instrument is that they
used to take these readings, a difference of 2.5 degrees centigrade is
a very minute difference. They would have to monitor your usage over a
long period of time to get day to day and seasonal variations in your
usage to have any chance of predicting what appliances you might be
using at any given time. However, as we both know, the police don't
always have to prove their case scientifically. I think that any
reasonable person would come to the same conclusion that you and I
have come to. Will that happen in court is anyone's guess.

Let me know if there is any of this that you can't follow. Please ask
for a clarification and I will try and explain a different way.

Good luck in court, Redhoss

Request for Answer Clarification by jelem2000-ga on 04 Dec 2005 08:16 PST
Hi redhoss-ga,
Thank you for your answer.
After checking with the electrician who installed the wire it turns out to be
 a 200amps wire size 2/0 . But the good news is that all the lights
were connected on
on both conductor (220v).So it does not change anything as far as the
temperature of the wires.
So we will see these guys in court....

Thanks again your answer was very helpfull.


Clarification of Answer by redhoss-ga on 05 Dec 2005 10:23 PST
I agree with you. I think you will be able to prove that they had no
basis to issue a search warrant for your home using the data from the
thermal imaging camera. I wish that I could testify for you.
jelem2000-ga rated this answer:4 out of 5 stars

Subject: Re: Electrical
From: hedgie-ga on 25 Nov 2005 16:55 PST
Good, well documented answer. 

Just one point is not clear:

"Assuming that all
the lights are powered by the same conductor, which is probably not
the case and is the worst case..."

I understood from
   electrical wire going to the house was anormaly hot

that they measured temperature of the external wire,
going from the post to the house. 

Then all load, all lamps, were on that conductor.

 Incidental comment:  It seems likely that warrant was issued based on 
pattern of the power consumption, as  described/mentioned here:

In court records, a number of suspects have blasted the detectives'
power comparisons as bogus, arguing that Grant and Goodpaster unfairly
compared their electrical usage to that of smaller homes with less
square footage and purposely failed to take into account factors such
as the existence of jacuzzis, swimming pools and other items that
raise power consumption.

I recall a case in which electric utility provided such data to the
police, and that act of 'cooperation with police' was found to be
improper, violating presumption of privacy.
 Considering that precedent, police may have been tempted to lie about
the source of the power data. They perhaps  invented  the infra
measurement as a cover, to hide real source of data. The story does
not fit, but real issue seems to be not technical but constitutional.
Is the 'power consumption pattern' , no matter how obtained, a
reasonable cause for a warrrant?
 Perhaps, as a protection, people will start applying for a permit ot
install a hot tub? I would start thinking about moving out of the
police state. Where do you live now? In Sudan, Saudi Arabia ..?

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