Recommended power line sizes
When installing your storage system, you must determine the AC and DC power line lengths
running from the storage system to the power source.
Recommended AC power line sizes
By properly designing longer AC power feeds, you can preserve voltage levels to the equipment.
The longer power feeds—the wiring from the breaker panel to the power strip, which supplies
power to the storage system and disk shelves—can often exceed 50 feet.
Note: Total AC wire length = breaker to wall or ceiling extension cable or ceiling drop.
The following tables list the recommended conductor size for 2 percent voltage drop for a
particular distance measured in feet (taken from the Radio Engineer's Handbook). The circuits in
the following tables are described in American Wire Gauge (AWG) measurements:
110V, single-phase
20A circuit
30A circuit
40A circuit
50A circuit
25 feet
12 AWG
10 AWG
8 AWG
8 AWG
50 feet
8 AWG
6 AWG
6 AWG
4 AWG
75 feet
6 AWG
4 AWG
4 AWG
2 AWG
220V, single-phase
20A circuit
30A circuit
40A circuit
50A circuit
25 feet
14 AWG
12 AWG
12 AWG
10 AWG
50 feet
12 AWG
10 AWG
8 AWG
8 AWG
75 feet
10 AWG
8 AWG
6 AWG
6 AWG
The following table lists the approximate equivalent wire gauge (AWG to Harmonized Cordage).
AWG
8
10
12
Harmonized, mm-mm
mm-mm = millimeter
squared
4.0
2.5
1.5
Calculating the length of DC wires for DS4243 disk shelves
If your DS4243 disk shelf is using DC power supplies, you must calculate the maximum combined
length of the positive and negative wires that connect the DC source and DC power supply by
using the variable definitions and examples provided.
Variable definitions
V
SOURCE
Voltage across the internal source resistance
V
OC
Voltage across an open circuit of the input source
V
LOAD
Voltage across a load, R
TEST'
connected to the input source
R
TEST
Test resistor of known value, that is, 10
Ω
at 300W
DS4243, DS2246, DS4486, and DS4246 Installation and Service Guide
64
Recommended power line sizes
