The two-wire 120-V supply line from the electric power company to the consumer h
ID: 1835644 • Letter: T
Question
The two-wire 120-V supply line from the electric power company to the consumer has a resistance of 0.03 ?.If a short circuit occurs at the consumer’s residence, find the current that flows through the short-circuit.
What size interrupting capacity for a circuit breaker would you choose for your home: 5000 A, 10 kA, 15 kA, or 25 kA?
So for the first question I was thinking Ohm's Law... V=IR which would give me a current of 120/0.03 = 4000A. However, I wasn't sure if there was anything that would change for short circuits?
And for the second, I know there are homes that have as low as 5000 A when it comes to size interrupting capacity for a circuit breaker...
But i'm not sure! Can anyone help me? Thanks in advance!
Explanation / Answer
Please ask if you have any doubt.I will help you.I am giving you answer for the previous doubt in this answer.
See Generally there will be another resistance or load to which there is a supply at the customers residence .
The question asks for if that load gets shor circuited ,Then the current passing through the line will be as you guessed
I = 120/0.03 = 4000A and yes i would choose 5000A ,which would be enough to detect and doesnt allow to flow more current.
If your doubt is cleared ignore this. see the 10s may have been correct ,but we have to have the resistivity values ,temperature values etc.So the 10s is just to get a feel that resistance decreased due to dissipation of heat.
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