Installation TW 5250 • TW 3500 • TW 1750
2-16 Elgar TrueWave
The formula below determines which ohms/100 feet entry is required from
Column 3. Read the corresponding wire gauge from Column 1.
(Column 3 value) =
V
loss
/[I
peak
x 0.02 x (cable length)]
Where:
Column 3 value =
Entry of the table above.
Cable length =
One way cable length in feet.
V
loss
=
Maximum loss, in volts, permitted within cable.
Special case: Should the V
loss
requirement be very loose, I
peak
may exceed the
maximum amperes (Column 2). In this case, the correct wire gauge is selected
directly from the first two columns of the table.
Example: A 20 ampere (I
peak
) circuit which may have a maximum 0.5 volt
drop (V
loss
) along its 15-foot cable (one way cable length) requires (by formula)
a Column 3 resistance value of 0.083. This corresponds to wire gauge size 8
AWG.
If the cable length was 10 feet, the Column 3 value would be 0.125 and the
corresponding wire gauge would be 10 AWG.
3. Aluminum wire is not recommended due to soft metal migration at the terminals
that may cause long term (on the order of years) poor connections and oxidation.
If used, increase the wire gauge by two sizes (e.g., specify 10 gauge aluminum
instead of 14 gauge aluminum).
4. Derate the above wire gauge (use a heavier gauge) for higher environmental
temperatures since conductor resistance increases with temperature.
Temperature Current
Degrees Capability
C F
40 104 80%