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The following formula is a guide to determine current draw so you can
choose the proper gauge power cable and fuses for your system. A 50%
amplifier efficiency rating is used as an average.
(Total 4-Ohm rate RMS output x 2) x 2 = Total Input Wattage
Total Input Wattage/Supply Voltage = Current Draw (in Amps)
Example:
Your
PPI4240
is 30 watts x 4 RMS @ 4-Ohms.
You would use the formula below:
30 x 4 = 120 watts Total Output
120W x 2 = 240W Input/12.5v = 19.2 amps Current Draw
Note: Notice that the total power is multiplied by two. This compensates for
the 50% efficiency of the amplifier. When you drop your impedance in half
you double the amperage.
Total Current Draw Length of Wire to Run (in Feet)
(in Amps) <3 <7 <10 <13 <17 <20 <22 <28
0 - 20 14 12 12 10 10 8 8 8
20 -35 12 10 8 8 6 6 8 4
35 -50 10 8 8 6 6 4 4 4
50 - 65 8 8 6 4 4 4 4 2
65 - 85 6 6 4 4 2 2 2 0
85 - 105 6 6 4 2 2 2 2 0
105 - 125 4 4 4 2 2 0 0 0
125 - 150 2 2 2 2 0 0 0 0
Note: The ground wire should be the same size as the power wire.
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