Is the earth of the water service faucet effective?
The ground lead might often tie to the faucet of water service when it is not possible to ground it easily by an electric washing machine etc.Is this effective as the earth? It is mostly made of the iron tube. wall about the water service tubeGenerally, the one made of the hard vinyl chloride pipe seems to be abundant about 1-3 meters are iron tubes ..there.. ahead from there. The iron tube seems to have from it to the polyethylene pipe ahead in the small portion recently.
Measurement of earth resistance of water service faucet that I made
Then, the ground resistance of such the one was measured. It is a faucet that I who understood the structure first set up.
It is connected with the well pump grounded by hard vinyl chloride (VP20) about 3m ahead of that by a left faucet's using the copper pipe of 7/8 inches by about 1m. There are a lot of impurities of the well water of my home, and there is one gram or more, and the total solid in the water of one liter can be said that it will conduct electricity easily from tap water.
It was an incapable measurement because it was able to measure even only 1k OHM in the earth resistance meter that I was using. When the polarity was changed with the tester and resistance with the iron frame was measured quick, it became about 40k OHM because the ground resistance of the iron frame in the building of my home was about 6 OHM. With this, it is completely understood not to use it as an earth. (The polarity is changed to decrease the influence of the polarization action by the generation of the battery with the earth pole and electroanalysis because the tester is direct current and measure it quick. ) It is necessary to make below 100 OHM or to make using with the leak breaker of a high sensitivity high-speed type together below 500 OHM if it uses it as an earth
Whether it is grounded is simply seen with the tester.
The method of seeing the standard whether grounded with the tester includes the method of simply measuring the power supply side of 100V and the voltage between earths. The tester was made AC120V cooking stove (internal resistance 8k OHM/V), and the voltage side of the outlet of 100V and the voltage between these water service earths were measured. There were 96V. Internal resistance of the tester Because it is 8k OHM*120=960k OHM, and the ground resistance of this water service is 40k OHM, 96V is values the same as the calculation.
This value becomes and the ground resistance of this water service earth becomes about 10k OHM even 99V. With this, it is not effective at all as the earth.
This method seems not to be suitable as the method of simply measuring the ground resistance. If it is a ground resistance of 1k OHM or more, if internal resistance of the tester is adjusted to about 10k OHM (About 10k OHM resistance is obtained for the tester in parallel), it is possible to measure it simply. However, there is a possibility that the leak breaker operates if the current of this circuit becomes about 10mA, and other leaks exist. (A usual leak breaker operates by 15-30mA. )
Measurement of earth resistance of existing water service faucet
Next, it is a measurement of the ground resistance of a single faucet that becomes it for the mop washing of the bathroom of my home. This is connected with town waterworks. When the appearance in the below the floor level is seen, it is buried with the iron tube by about 10cm in the soil through mesne of the block wall as shown in the photograph on. The soil is always damp. It is laid from it ahead with the hard vinyl chloride.
A left photograph is a tie of the iron pipe of the faucet in the ground bar etc. to the earth because it had used this faucet for the washing machine before. This was removed and measured this time.
When the ground resistance was similarly measured with the tester, it was about 2.5k OHMThe ground resistance seems to fall if still buried in the soil even a little. It can be said that it is not suitable for this to use the faucet of water service as an earth.
Calculation of resistance of water in vinyl chloride pipeCalculation of resistance of water in vinyl chloride pipe
Resistivity of stream water and water supply P is about 1 to 20 [k OHM cm] (about 10 to 200 [OHM m])
Resistance at both ends of water in vinyl chloride pipe VP20 1m R is calculated. The inside diameter of the pipe It is 2cm.
R = P*L / S
= P*L / 3.14*r2 (L = 100cm r = 1cm)
If it adopts and being possible [nari] to come is calculated, it becomes about 32-640[k OHM]. Resistance in the vinyl chloride pipe of 3m is sure to become about 100k OHM - about 2M OHM for the above-mentioned "Earth resistance measurement 1 of the water service faucet". The actual measurement value 40k OHM seems to be effective more than the resistance of water of the insulation resistance between the pipe and the wall of copper because it is considerably smaller than this.
As forwater in the water service pipe, the thing that hardly contributes to the ground resistance of the faucet earth (below 100 OHM or 500 OHM)is understood as a result.
The insulation pipe of 1m will be installed in the hot water side of 50cm on the water side of a metallic tank of an electric water heater for the electric shock prevention. Because it is this length and is water and a thing that it is possible to insulate it, the thing that should not be able to be grounded in the water service tube of the vinyl chloride is understood from this thing.
Because the current that flows in water in the vinyl chloride pipe doesn't diffuse, and be constant the current density, the ground resistance doesn't fall though the current diffuses in all directions as follows and the ground resistance lowers to the earth driven to the soil.
Conclusion(The water service pipe cannot used as an earth below 100 OHM. )
The earth of the water service tube might be not effective at all.It is not possible to use it electrically as an earth if it doesn't measure it with the earth resistance meter. When everything of course has been buried with a metallic tube in the soil by a long distance, it is effective electrically. However, do not usually use the water service tube as an earth only in the following cases that the water service tube can be legally used as an earth pole.
When you may use the water service tube as an earth pole
The metallic water service conduit that is laid underground under the soil, and theelectrical resistance value between the earth keeps a value below 3 OHMcan use this for A seed earth construction, B seed earth construction, C seed earth construction, D seed earth construction, and other earth construction by obtaining the approval of the manager of the water service conduit. (Article 22 of electric equipment technology and standard interpretations)