Electrical

Electrical Questions? Ask an Electrician Online.

# OHMS Related Questions

According to NDT-ED.org, “The scientific definition of one ohm is the amount of electrical resistance that exists in an electrical circuit when one amp of current is flowing with one volt being applied to the circuit.” OHMS are often used by professionals and handymen alike. However many times there are issues related to the OHMS meter that bring questions with no answers.

Listed below are a few questions answered by the electrician Experts on ohm related issues.

## I need to wire a 0-90 ohm sending unit in a truck. What kind of wire do I need?

The wire you require should be one that carries less than 1 amp. In fact, a load of .133 amps should be just right. With that in mind, choose the smallest gauge automotive wire that you can buy at your local parts store.

## What is the minimum insulation in megohms?

The minimum insulation to get the desired resistance in megohms would depend on the insulating material that is being used. A megger, or megohm meter, would be needed to measure megohms. It cannot be measured using a standard multimeter.

## I need to take resistance readings of a 120 VAC / 60 Hz Superior Pro-Heat radiant floor heating cable. How can I use a digital ohm tester to get this done?

To begin with, take one lead of the meter and put it into the slot with the horse shoe icon. Then insert the other lead into the COM slot. After this is done, move the dial to the OHM setting and set it at 20k for this particular reading. Then, take one lead and place it on the black wire and the other lead on the white wire. The reading you get in "ohms" will be the resistance. Follow the manual and repeat this process for each set of wires.

## To eliminate the possibility of a pump having become faulty, what should the ohm reading be for a 1/3 horse power motor or a 1/2 horse power @ the control box? The motor is 240v.

The motor will draw the amount of current mentioned below if it is running at full load.

1/2 HP motor at 240 volts - fla is 4.9 amps
1/3 HP motor at 240 volts - fla is 3.6 amps

The draw will be less if it is running at less than a full load.

The readings are based on the National Electrical Code. Also, every motor should have a label that has the values for that motor printed on it and these values could vary slightly from what is given above. A motor that draws more current than the rating on it could either be overloaded or faulty.

Based on the ohms law, the resistance should be 49 ohms for the 1/2 HP motor and 67 ohms for the 1/3 HP motor.

An ohm meter is a simple instrument that measures the amount of electrical friction in an electronic device. If you are not sure how to operate a OHM, the best bet would be to contact an Expert.

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