They don't. the voltage decreases & the amps will increase. The longer the wire the more resistance the less voltage. In order for you power, KW or VA to remain the same, if your voltage drops your amps go up, if your voltage goes up your amps will drop. (I=P/E),(P=ExI)(E=P/I)
I=amps
E=volts
P=power or watts or better yet VA
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The answer above presumes that KW or VA remains the same in a circuit regardless of what you do to it. They do not. I do not intend to be argumentative but here is my answer.
Adding resistance IN SERIES with a circuit decreases the amps that would otherwise flow because it has to overcome more resistance. Since conductors have resistance and are by their very nature IN SERIES with a load, adding length to conductors can, does, and will decrease the amps across the entire circuit.
If you aren't into reading technical descriptions, stop reading now. The simple answer is in my second paragraph above, and is all you probably needed or wanted to know.
What confuses people is how the circuit behaves when you add another load IN PARALLEL, which is how most circuits you and I use are wired. Adding a load IN PARALLEL will increase the amps of the overall circuit because it decreases the net resistance of the circuit. The best comparison that will help you understand this is a water line. If a water line has two faucets with only one faucet open, you have a certain amount of pressure inside to water pipe. If you open both faucets you now have more water flowing and a net decrease in pressure within the pipe. Comparing a circuit to a water pipe in this manner is not far fetched. It is exactly how and why you get more amps when you add lights to a circuit. They are connected IN PARALLEL to each other.
Getting back to our conductors, however, you can see that the first leg of conductors from the breaker to the first load is carrying the amps of the whole circuit. Each leg from one load to another carries decreasing amps because it is carrying amps to fewer loads. The amount of power lost in these conductors is equal to I2R. Plugging in this value to the other formulas allows you to calculate how much voltage is "dropped" across any leg of the circuit, knowing the voltage applied and getting the resistance of the conductors from the code book.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
A #10 wire has the capacity for 30 amps. No breaker larger than 30 amps should be used to protect the circuit.
Depends on how many amps it pulls and the size of the wire in the circuit.
To do so LEGALLY, the circuit breaker must not be rated at a capacity (in AMPS) greater than the SMALLEST wire.
10 AWG should never carry more than 30 Amps.
Branch circuits wire sizes are governed by the connected load amperage of the circuit. The wire size ampacity then governs the size of the breaker that is used to protect the circuit from overloading. For general home wiring circuits the conductors used are, receptacles and lighting #14 - 15 amps, dedicated circuits load dependant, hot water tank and baseboard heaters #12 - 20 amps, clothes dryer #10 - 30 amps, range #8 -- 40 amps.
If you have 100 amp wire, you can use it for a 60 amp circuit, or for any circuit of 100 amps or less. But if you have a 60 amp circuit, 60 amp wire is thinner and cheaper than 100 amp wire.
The wire rating for a # 12 wire is 20 amps. If you are going to continuously load the circuit you need to de-rate the wire by 80%. This brings the current down to 20 x .8 = 16 amps. The wire rating of a # 10 wire is 30 amps. 30 x .8 = 24 amps.
Yes, on a 2-wire circuit you will always have the same current anywhere in the circuit unless there is another path (fault) for it to travel.
12 guage wire israted for 20 amps and 10 guage is rated for thirty amps! 12 gauge is what is required, as it is rated for 20 amps. 10 gauge is rated for 30 and will be more then enough. Oversizing wire in your case isn't necessary. The thicker 10 gauge wire is harder to work with and will more then likely cost more.
15 amps
If the wire used on the circuit is sized for 15 amps (usually 14 gauge) you run a very serious risk of fire.If the wire used on the circuit is sized for 25 amps (usually 10 gauge, good for 30 amps) there is no increased danger.Additional InformationIf you don't know if the wire is sized for 25 amps, DON'T DO IT!A 25 amp circuit would require 10 AWG wire. The fire hazard mentioned above is real and you shouldn't ignore that advice.
When the wire you are protecting is a #10, rated at 30 amps.
A #10 wire has the capacity for 30 amps. No breaker larger than 30 amps should be used to protect the circuit.
Number 10 thnn copper wire.
Depends on how many amps it pulls and the size of the wire in the circuit.
The wire can be as big as you want to carry 6 amps. As a comparison, the smallest home wiring power circuit uses a #14 size wire and it is rated for 15 amps. In the UK a wire of 0.75 sq. mm is rated at 6 amps for portable appliances with occasional use. For a permanent installation a cable of 1 sq. mm. or more should be used. House wiring uses 2.5 sq. mm cable in a ring circuit to supply power sockets.
No such circuit exists.