By pressiong the 2 buttons,check the side by side lines one by one.If the light is on,it is phase line,otherwise it is the null line,In case there is a break in the line,move until hte light is off.That is the break point.

• 按两键)以铺好的三芯或四芯电缆或电线，可将另一端全部良好接地，再如图分别检测灯亮则通，此法适合楼房装修布线，将主线接地，边安装边测试。