-7%

33%

33%

33%

M

M

M

B-2

B-2.1

Calculate voltage drop by the following equation:

where,

=

Line current in amperes

=

Resistance of line in ohms

=

Reactance of line in ohms

=

Phase angle between voltage and current if phase angle

is not known, assume a phase angle of 36.9 degrees

corresponding to a power factor of 0.8.

B-2.2

The above equation is simplified, but usually provides acceptable results. In

the above equation, obtain the conductor resistance and reactance values as a function

of gauge size from NEC Chapter 9, Tables 8 and 9 (2002 Edition). Note that NEC

conductor resistance values are based on 75 C (167 F) and will usually require

correction to the actual expected temperature (refer to NEC Chapter 9, Tab le 8, or the

first example in paragraph B -6.1 for how to convert the resistance to a different

B-3

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