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Saturday, February 13, 2021

Calculation of the section of DC electric cables

 

The formula to use for copper conductors is:


                           S = 0.017 x L x I / PT
S = section of the copper conductor expressed in square millimeters
L = driver's outward + return length expressed in meters
I = the intensity expressed in Amperes
PT = voltage loss accepted on the cables expressed in
Volts

  Manual
 Calculation of the length:


Whatever the nature of the hull, there must always be a "go" or positive conductor in
general red and a black "return" or negative conductor.
As specified in Division 240, the shell material should never be used in
as a driver.

Intensity:

The nominal current is sometimes provided: in this case, nothing could be simpler.
Often only the power of the device is indicated. In this case, it is necessary to calculate
the intensity using the following formula:
P = U x I or I = P / U
P = Power expressed in Watts
U = nominal voltage of the installation (12 V, 24 V or 48 V) expressed in Volts
I = Intensity expressed in Amps

PT or loss of voltage in the cables:
A current flowing through the cables generates a voltage (Ohm's law).
Division 240 specifies that this must remain less than 5% of the nominal voltage of
the installation is:
Maximum PT allowed in 12 V = 0.6 V (5% of 12 V)
                                           24 V = 1.2 V (5% of 24 V)

Reasonable PT a priori in 12 V = 0.3 V (2.5% of 12 V)
                                            24 V = 0.6 V (2.5% of 12 V)
     2. Example:

Installation of a 110 W 12 V pump


Distance between the fuse or circuit breaker and the pump via the complete routing:


meters. Round trip + return = 14 m.
The nominal current is: 110/12 = 9.2 A
The strictly minimum section of the conductor must be:
 0.017 x 14 x 9.2 / 0.6 = 3.6 mm²


The so-called "reasonable" section is:


  0.017 x 10 x 9.2 / 0.3 = 7.3 mm²
A section of 4² is sufficient "legally" but a conductor of 6 is preferable.
As far as I'm concerned, I prefer to send the maximum voltage on the pumps and I
will carry out the installation in 10²

 

The formula to use for copper conductors is:


                           S = 0.017 x L x I / PT
S = section of the copper conductor expressed in square millimeters
L = driver's outward + return length expressed in meters
I = the intensity expressed in Amperes
PT = voltage loss accepted on the cables expressed in
Volts

  Manual
 Calculation of the length:


Whatever the nature of the hull, there must always be a "go" or positive conductor in
general red and a black "return" or negative conductor.
As specified in Division 240, the shell material should never be used in
as a driver.

Intensity:

The nominal current is sometimes provided: in this case, nothing could be simpler.
Often only the power of the device is indicated. In this case, it is necessary to calculate
the intensity using the following formula:
P = U x I or I = P / U
P = Power expressed in Watts
U = nominal voltage of the installation (12 V, 24 V or 48 V) expressed in Volts
I = Intensity expressed in Amps

PT or loss of voltage in the cables:
A current flowing through the cables generates a voltage (Ohm's law).
Division 240 specifies that this must remain less than 5% of the nominal voltage of
the installation is:
Maximum PT allowed in 12 V = 0.6 V (5% of 12 V)
                                           24 V = 1.2 V (5% of 24 V)

Reasonable PT a priori in 12 V = 0.3 V (2.5% of 12 V)
                                            24 V = 0.6 V (2.5% of 12 V)
     2. Example:

Installation of a 110 W 12 V pump


Distance between the fuse or circuit breaker and the pump via the complete routing:


meters. Round trip + return = 14 m.
The nominal current is: 110/12 = 9.2 A
The strictly minimum section of the conductor must be:
 0.017 x 14 x 9.2 / 0.6 = 3.6 mm²


The so-called "reasonable" section is:


  0.017 x 10 x 9.2 / 0.3 = 7.3 mm²
A section of 4² is sufficient "legally" but a conductor of 6 is preferable.
As far as I'm concerned, I prefer to send the maximum voltage on the pumps and I
will carry out the installation in 10²

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