Micro
ARE-M Series 24V Chargers, Single Phase
Installation
PM990-1070-24, Issue 12
2-3
2.2.2
Selecting and Sizing DC Power Cables
Protective circuits, overall system performance, and safety depend on the proper sizing of DC cables for
ampere ranges and acceptable DC voltage drop. Read the electrical installation section before sizing the
DC cables.
Perform the following procedure to determine wire size.
1.
Calculate the minimum circular mils (CM) required for copper wire using the following formula:
V
L
I
CM
∗
∗
=
2
.
22
where:
CM = minimum area of circular mils in the cable
I = maximum current (in amps)
L = one-way cable length (in feet)
V = allowable loop voltage drop (in volts)
Example:
Assume a maximum output current of 25 amperes, an allowable loop voltage drop of 0.5 volts, and a
distance of 50 feet between the charger and the load.
I = 25 amperes
L = 50 feet
V = 0.5 volts
000
,
55
)
5
.
0
(
)
50
)(
25
)(
2
.
22
(
=
=
CM
11.
After calculating the minimum circular mils, select the proper copper wire size from Table 2-2;
always choosing the next larger wire size if the area rating falls between values. For the above
example, select 2 AWG (35 mm
2
) wire.
12.
Determine the minimum wire size for ampacity according to the code authority having jurisdiction in
your location.
13.
Select the larger of the sizes calculated for voltage drop or ampacity.
