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Insulation resistance is measuring the integrity of a conductor's insulation, therefore there is no upper limit as such. Most insulation resistance testers will indicate either >200 (Megohms) or >999 (Megohms) if they reach their maximum measuring capability. What you should be concerned with is the MINIMUM reading permissible: the current edition of BS7671 (17th Edition IEE Wiring Regs) specifies a minimum value of 1 Megohm (1 million ohms) as 'acceptable', but anything lower than 2 Megohms will require further investigation. Some electrical contractors would investigate much higher readings, especially if comparing readings with other circuits that have been tested at the same time, and which have given very high readings.

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What test would identify a short circuit in a lighting circuit?

earth continuity insulation resistance polarity


When a multimeter is set to measure resistance what reading would you expect when the probes aren't touching?

If the test leads are not in contact with anything, the needle or pointer of an analog meter will be resting at the left most position. This is represents an infinite amount of resistance, or an "open circuit"; it is also safe to say there is the no continuity, or path between the black and red probes.


Why must power be turned off when measuring the resistance of a circuit?

If an external Voltage is applied to a multimeter while the multimeter`s function switch is in the Ohm meter position then the Ohmmeter is apt to be destroyed or disabled. Therefore the simplest answer is that the power must be turned off in order to avoid damage to the Ohm meter and possibly to yourself caused by Voltages present in the circuit while the power is own. Another reason of course is because a valid Ohm reading can not be obtained while Voltages are present across the resistance that is being measured because the Ohmmeter itself applies a Voltage across the resistance and then a sampling of the current through the unknown resistance is used by the Ohmmeter`s circuitry to cause a calibrated deflection of the Ohmmeter and thus display on the meter`s dial the Ohmic value of the unknown resistance. For the same reasons as above it is also a good practice to discharge all the capacitors in the circuit after the power is turned off and before any in circuit resistance measurements are made.


How does read-out integrated circuit works?

Read out integrated circuit refers to integrated circuit specifically used for reading detectors of a particular type. These are used in detectors where the sensitivity is very low and using a discrete circuit may not be useful as noise may be large enough to cover up whole signal.


What reading would you get if a voltmeter is placed in series across a load in closed circuit?

In series and across the load are contradictory statements. Some voltmeters are really capable of voltage, current and resistance measurements. To measure current the meter either has to be a clamp on type or one that goes in series with the load. You measure voltage drop across the load as described above.

Related Questions

What is the maximum insulation resistance reading on a 800A busbar?

infinite


If you are using a multimeter as an ohmmeter and you get a reading of maximum resistance what does that tell you about the circuit you are measuring?

Did you mean "maximum RESISTANCE" or "maximum VALUE"? If the former, then, you have a ZERO reading, meaning there is high resistance, and no electrical connectivity. If the latter, you have a ONE (or 100%) reading, meaning there is NO resistance, or absolute electrical connectivity. As an analogy, if you turn on a plugged-in, working, lamp, then it has NO resistance, such that power flows easily through the cord; if it didn't turn on, then there IS resistance, such that no power flows, possibly due to broken wire, bad switch, burned-out bulb, or blown fuse.


What test would identify a short circuit in a lighting circuit?

earth continuity insulation resistance polarity


Does an Ohmeter that has an infinite reading indicates an open circuit?

Yes, an infinite reading on an Ohmmeter usually indicates an open circuit. This means that there is a break in the circuit, preventing the flow of current and resulting in the high resistance reading.


Why remove resister from circuit to measure resistance?

a meter uses its own supply to measure resistance. you dont have to remove the resistor from the circuit but you must isolate it from the circuit supply to get an accurate reading.


What is resistance reading?

A measurement of opposition to electric current flow in a component or circuit.


Why does the voltage reading of 110 circuit is less than expected?

A load or a resistance


How can a multimeter be used to measure the resistance of a circuit component?

A multimeter can be used to measure the resistance of a circuit component by setting it to the resistance measurement mode, connecting the probes to the component, and reading the resistance value displayed on the multimeter screen.


What should be the insulation resistance in a electrical circuit?

As we know thath insulators are the materials which are mainly use to insulate any conducting body from the LIVE supply whether 3Ph or single phase, so the reristence of such an insulator should be infinity as it should be provide maximum resistance to the flow of current through it.


How can an ammeter loading effect the circuit under test?

Since internal resistance of the ameter will increases the resistance of the circuit. Thus decreasing the current giving an errorenous reading.


Why must do the insulation testing in circuit?

Insulation resistance testing involves applying a voltage across a dielectric, and measuring the resulting current and resistance. However, in order to get a proper reading, any electrical charge still within the system needs to be taken out, so as not to mess with the readings.


How can I test for a short circuit in a circuit?

To test for a short circuit in a circuit, you can use a multimeter set to measure resistance. Disconnect the power source, then place the multimeter probes at different points in the circuit. If the resistance reading is very low or zero, it indicates a short circuit.