How to calculate the ampacity of a electrical conductor?. I don't mean using tha table? - ampacity table
If you know the size of a conductor, such as "amps" Multiples, which may cause the calculation
Monday, January 11, 2010
Ampacity Table How To Calculate The Ampacity Of A Electrical Conductor?. I Don't Mean Using Tha Table?
7 comments:
It's really a question of disappation heat. The colder it is the last cable can carry. As current through a wire that is heated on the basis of their resistance. The cable will carry when it melts and falls away. The insulation was melted or burned. In an ice bath, a # 12 Wire to cover 100 also bear when restricted to 20A in a typical house, assuming the NEC standard tables such as a temperature of 86 degrees C and an air speed of 2 mph. Cable is not so hot on a windy day or when the air temperature is cooler.
It's really a question of disappation heat. The colder it is the last cable can carry. As current through a wire that is heated on the basis of their resistance. The cable will carry when it melts and falls away. The insulation was melted or burned. In an ice bath, a # 12 Wire to cover 100 also bear when restricted to 20A in a typical house, assuming the NEC standard tables such as a temperature of 86 degrees C and an air speed of 2 mph. Cable is not so hot on a windy day or when the air temperature is cooler.
NEC ampacity table is based on the equations IPCE Neher McGrath. The calculation is very hot because of the complexity involved in a cable. The current capacity of computer calculated.
Assuming that the heat is conducted without regard to the heat transfer coefficient between copper and PVC and PVC between air and the environment. radial direction of the heat transfer formula is simplified as follows and can be calculated without a computer ..
W T1 = K (- T2) / (CONST)
(CONST) = (3.28) [ln (D2) - Ln (D1)] / [2 'L]
W = [I ^ 2] [R]
R = p [L / (D1 ^ 2)]
W = heat flow in watts
K = thermal conductivity of PVC = 0.19 W / m / C
T1 = temperature = 75 C copper specifications for NEC
T2 = temperature = 30 ° C per NEC specifications
D2 = diameter in inches of insulated wires
D1 = diameter in inches of copper
2 Pi = 2 (3.14) = 6.28
= 3,28 meters to feet conversion factor
L = length m copper
I = amperes current capability
R = resistance in ohms AC Cooper
R1 = resistance of copper = 10.5 ohms / cirmil / ft
L = foot length of copper
NEC ampacity table is based on the equations IPCE Neher McGrath. The calculation is very hot because of the complexity involved in a cable. The current capacity of computer calculated.
Assuming that the heat is conducted without regard to the heat transfer coefficient between copper and PVC and PVC between air and the environment. radial direction of the heat transfer formula is simplified as follows and can be calculated without a computer ..
W T1 = K (- T2) / (CONST)
(CONST) = (3.28) [ln (D2) - Ln (D1)] / [2 'L]
W = [I ^ 2] [R]
R = p [L / (D1 ^ 2)]
W = heat flow in watts
K = thermal conductivity of PVC = 0.19 W / m / C
T1 = temperature = 75 C copper specifications for NEC
T2 = temperature = 30 ° C per NEC specifications
D2 = diameter in inches of insulated wires
D1 = diameter in inches of copper
2 Pi = 2 (3.14) = 6.28
= 3,28 meters to feet conversion factor
L = length m copper
I = amperes current capability
R = resistance in ohms AC Cooper
R1 = resistance of copper = 10.5 ohms / cirmil / ft
L = foot length of copper
The above response has good points.
It is also necessary to know what you are looking for.
How much voltage drop can be tolerated on the length of the cable.
How can the loss of power, the hot wire to resist?
Are not you worried and you are interested in. If the wire is melted?
Are you interested if the insulation is melted?
Your question is a bit to respond to Vaughan. Sorry.
A good general rule is 4 amperes per square millimeter.
Home Wiring:
Size # 14, 15 A max
Thickness 12, 20 A max
Loose wiring as the wiring of electronic equipment, cables can carry more than the rating of household wiring, since it ventilated and the temperature rises any longer.
Visit: http://www.cerrowire.com/default.aspx?id ...
http://www.wiktel.com/standards/ampacit. ...
http://www.powerstream.com/Wire_Size.htm
http://www.epanorama.net/documents/wirin ...
Since the electrical conductivity is often the effect of "skin" is only through knowledge of the cross section is not sufficient. In addition, the conductivity depends on the type of driver.
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