Precision Power PPI4240 User Manual
Page 4
3
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.