Code:
  <log4net>
    <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
      <file value="Logs/Application.log" />
      <appendToFile value="true" />
      <immediateFlush value="true" />
      <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
      <rollingStyle value="Size" />
      <maximumFileSize value="10MB" />
      <maxSizeRollBackups value="5" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%newline[%date{dd MMM yyyy HH:mm:ss.fff}](%thread) %-5level: %message (%location)%newline" />
      </layout>
    </appender>
    <root>
      <level value="DEBUG" />
      <appender-ref ref="RollingFileAppender" />
    </root>
  </log4net>