The electrician need to be familiar with the application code

Using low voltage test pencil
Low voltage test pencil is a commonly used auxiliary electrical appliances safety. Used to check whether the shell of a conductor under 500V or a variety of electrical equipment is charged. An ordinary low voltage test pencil, portable, as long as the master principle electroscope, combined with electrical principle known, flexible use of many skills.
(1) determine the AC and DC electric formulas
Pencil judgment of AC DC AC DC bright dark,
AC DC neon bright neon light body, one end.
Explain：
First tell the readers a bit, before the use of low voltage test pencil, must be in the charged body has confirmed the test; before the confirmation test pencil is normal, do not use. In distinguishing between AC and DC power, it is better to make comparisons between "two electric", so that is obvious. Measuring alternating current at both ends of the neon lit, measuring DC when only one end in very bright neon.
(2) determine the DC polarity formula:
Pencil judgment is negative, we should be careful observation of neon,
The front end is bright and negative, and the rear end is bright positive.
Explain：
The front end of the neon electroscope refers to the nib end, holding one end of the tube end to the front, bright as the negative, and positive. Note: test power supply voltage of 110V and above; if the people and the earth insulation, hand power either pole, another hand the test pen, pencil metal head touching the measured power the other pole, polar front neon bright, the power is measured by touching the anode; if the back end of the neon tube very shiny, power the measured contact is positive, which is based on the principle of DC and one-way flow of electrons from cathode to anode flow.
(3) determine the DC power supply has no grounding grounding, positive and negative difference formula
The substation DC coefficient, can not touch the shiny pencil;
If the light is near the tip of the pen, there is a grounding fault on the positive pole;
If light is near the end of the finger, the ground fault is at the negative pole.
Explain：
Power plant and substation DC coefficient, is the insulation on the ground, people standing on the ground, with the electroscope to reach the anode or cathode, the neon tube should not be bright, if the bright, DC system grounding phenomenon; if shine at one end close to the tip of the pen, is the electrode; if shining in the near one end of the finger is negative ground.
(4) determine the in-phase and out of phase formula
Judge two lines of the same difference, each hand holding a pen,
The two feet are insulated from the ground. Each two touches each other,
With the eye to see a pen, do not light the same phase, light is different.
Explain：
Remember that both feet and ground must be insulated during this test. Because most of China is 380/220V power supply, and is widely used in transformer neutral grounding, so do the test, we must avoid insulation between the human body and the earth, forming a loop, so as to avoid the error judgment; test, two and the bright display, so it only can see a.
(5) 380/220V three-phase three wire power supply line phase grounding fault code
Star connection three phase, two light touch pen,
The remaining one is weak in brightness and the phase conductor has been earthed;
If it is almost not visible, the fault of the metal grounding.
Explain：
The two side power transformers generally are connected into a Y shape, not connected to the three-phase three wire system in the neutral point, with electricity strokes and three phase lines, there are two slightly brighter than usual, and the brightness of another root on to some of the weak, says the root brightness weak phase is the phenomenon of ground, but also not too serious; if the two are very bright, and the remaining one almost invisible light, is the root of metal phase grounding fault.