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According to NDT-ED.org, the term OHM is used to define the amount of electricity resistance that exists in an electrical circuit when 1 amp of current is passing with 1 volt being applied to the circuit. OHM is also used to measure electrical impedance in an alternating current circuits. It is named after German physicist Georg Simon OHM. And the electronic device used for the above mentioned purpose is called an OHM meter or OHM tester which has a ruled scale with an indicator needle or digital display, a range selector and two probes. The article below has answers to some of the frequently asked questions on this issue. What type of wire do I have to use to wire a 0-9 OHM sending unit in a truck?
You can use the smallest gauge automotive wire that carries less than 1 amp. In fact, a load of .133 amp should work for you. You can get those wires from a local parts store. What should be the minimum insulation in MegOHMs (A unit of resistance equal to one million OHMs)?
Insulation resistance measures the integrity of a conductor’s insulation and it has no upper limit as such. Most of the insulation resistance testers would indicate either below 200 megOHMs or below 999 megOHMs. However, it depends on the insulating material that is being used. As it can not be measured using standard multimeter, you have to use a megger/megOHM meter to measure the megOHMs. How do I use a digital OHM tester to take resistance reading of a 120 VAC/60 Hz superior pro-heat radiant floor heating cable?
To start with, take one lead of the meter and put it in to the slot. Then insert the other lead in to the common slot. Move the dial and set it at 20k before you place one lead on the black wire and the other lead on the white wire. The reading you would get in OHMs is the resistance. You have to repeat the same process with each set of wires. What should be the OHM reading for a 1/3 horse power or ½ horse power motor at the control box with a 240 v motor?
Running at a full load, a ½ horse power motor at 240 volts would draw 4.9 amp current and for a 1/3 horse power motor it would be 3.6 amp. The draw of current would be significantly less if the motor is running at less than full load. According to the National Electrical Code, every motor should have a label indicating the values for that motor and these values cold vary slightly. However, if a motor draws more current than the rating on it, it could be considered as faulty. Going by the OHMs law, the resistance should be 49 OHMs for the 1/2 horse power motor and 67 OHMs for the 1/3 horse power motor. An OHM meter is a simple instrument that measures the amount of electrical friction or resistance in an electronic device. Measuring the resistance of some electrical components can be tricky. Sample this, if you try to measure the resistance of a capacitor you will get zero initially and then you will watch the meter slowly increase to infinity. Also, an entirely opposite effect is seen when measuring the resistance of a coil. If the device you are measuring interferes with the current in some way, you could get a wrong reading. However, if you are not sure of how to use an OHM meter, you can better ask an electrician to do this for you.
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