Calculation problem formula to solve?

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Danny89

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Location
Indian Land
Question:
12awg stranded in Oates copper conductors are run 100 ft; the current through the circuit is 20 amps. What is the power loss of the conductors?


Can someone please work this problem step by step and show me how to solve this and with what formula? Thanks.


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Dennis Alwon

Dennis Alwon

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Location
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Retired Electrical Contractor
Danny89 said:
Question:
12awg stranded in Oates copper conductors are run 100 ft; the current through the circuit is 20 amps. What is the power loss of the conductors?


Can someone please work this problem step by step and show me how to solve this and with what formula? Thanks.


Sent from my iPhone using Tapatalk
Click to expand...
Do you know the formula ?
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
230128-1653 EST

Danny89:

There are many bits of information not provided. So you make assumptions and state these in your answer.

How many wires is the power being dissipated in?
What is the resistance per foot at whatever is the assumed temperature of the wire with the current flowing?
Are the wires all the same size and material?

What equation do you need to use to solve the problem?

.
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
gar said:
230128-1653 EST

Danny89:

There are many bits of information not provided. So you make assumptions and state these in your answer.

How many wires is the power being dissipated in?
What is the resistance per foot at whatever is the assumed temperature of the wire with the current flowing?
Are the wires all the same size and material?

What equation do you need to use to solve the problem?

.
Click to expand...


Gar the ohms per foot is in Chapter 9 Table 8 as mentioned above. I think one has to assume alot when it comes to test question, for example
the number of wires . Also you must assume they are all the same size.

I think this can be solved with just the voltage but I am a shlub anyway. LOL
 
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winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
You know current, so power is just I^2*R. Voltage doesn't matter.

You get R from the conductor length and chapter 9 table 8.

The answer will change if '100 feet' means a total of 100 feet of wire, or a single phase circuit that goes out 100 feet (200 feet total wire) or 3 phase (300 feet total wire).

Jon
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
230128-2124 EST

Danny89:

You are given the current. You need to figure out your wire resistance at this operating current level and wire temperature. Then you can calculate the power loss in the conductors.

.
 
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