INSTALLATION
MANUAL
© Scania CV AB 2018, Sweden
Electrical cables
03:01 Issue 11 en-GB 11
Calculating cable cross-section
Use the following formula to calculate the cable cross-section:
U
f
= Permissible voltage drop, V
I = Current consumption, A
L = Length of cable, m
A = Cable cross-section, mm
2
0.0175 = copper resistance when L = 1 m and A = 1 mm
2
at +15°C.
The highest permissible voltage drop for cables between alternator, starter motor and
battery is 2.5% or 0.6 V. For other cables, the highest permissible voltage drop is
5.0% or 1.2 V.
Each connection point gives a voltage drop of 0.1 V at connection points and 0.3 V
at joints.
u
f
= I x
0.0175 x L
A
When installing an electrical component with a known load (I, ampere) and location,
which gives the cable length (L), the necessary cable cross-section is calculated as
follows:
The voltage drop for connection points and any joints must be subtracted from the
maximum permissible voltage drop before calculating the cable cross-section.
For durability reasons, the minimum permissible cable cross-section for electrical ca-
bles routed to the engine is 1.5 mm
2
for single-core cables, and 1.0 mm
2
for multi-
core cables.
The minimum permissible cable cross-section for a specific load also depends on
which type of electrical cable is used. Scania recommends the use of PVC 105°C
electrical cable type RK.
A = I x
0.0175 x L
U
f
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