All voltage reading are usually read with a volt meter. This volt meter can be a hand held unit like electricians use.
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as an electrician i would first check the main breaker with a rated voltage tester for voltage i would first ckeck the meter side by placing one tester lead on one of incoming phases or wire and place second lead on the other phase or other wire. i should read 240, or 230, or 220 volts depending on where the taps are in the transformer. if not call the power company. if it does read any of them voltages i would then check the load side of the main breaker by putting my leads on one breaker and the one right below it generally every other breaker is a different phase again i should read 240 volts or close. if not the main breaker may be bad. if you know what breaker or circuit its on you could test it by placing one lead on the screw where the wire is and the other on the neutral or ground bar here you should read 120 volts or close if not breaker is bad. it maybe as easy as tightening the screw or screws so shut the breaker off first and then tighten.
The reason 277v leg to leg does not measure 554 volts is each phase of the system is 120 degrees out of phase with each other and there fore will not read 554v leg to leg but 480v lag to leg. If you take 277 times the square root of 3 it will equal 480. The meters measure Root Mean Square or rms voltages and are designed to take this into their readings.
You are probably measuring between the one leg of the 240 volts and the neutral or the ground pin connection. Take the measurement from the two outside blade holes on the receptacle. There the reading should be 230 to 240 volts. Between either of the outside blade holes and the neutral or ground you should read around 120 volts.
A DC ammeter will read zero
To measure volts accurately in an electrical circuit, use a digital multimeter set to the voltage range needed. Connect the multimeter probes to the circuit's positive and negative terminals. Read the voltage displayed on the multimeter screen for an accurate measurement.
To read volts on a multimeter, set the dial to the voltage setting, typically labeled as "V" or "VDC." Connect the red probe to the positive terminal and the black probe to the negative terminal of the circuit or component you want to measure. The display will show the voltage reading in volts.
To measure volts accurately in an electrical circuit, you can use a digital multimeter. Set the multimeter to the voltage setting, connect the probes to the circuit's positive and negative terminals, and read the voltage displayed on the multimeter screen. Make sure to select the appropriate voltage range for the circuit you are measuring to ensure accurate results.
A multimeter reads volts by measuring the electrical potential difference between two points in a circuit. It does this by sending a small known current through the circuit and measuring the voltage drop that occurs. The multimeter then displays this voltage drop as the voltage value on its screen.
You can pull 12 volts off of any single battery in the circuit. The output from each battery never changes, it's always 12 volts. Those batteries are wired together in SERIES to increase the final output voltage of the entire circuit to 48 volts. To demonstrate this, place a voltmeter across the positive and negative terminal of any battery in the system. It will read 12 volts, regardless of which battery you're measuring across. Now place the voltmeter from the positive terminal on one battery and the negative terminal on a different battery. Depending on how many batteries you're measuring across, it will read 24, 36 or 48 volts. Practical application - connect your 12 volt device from the positive terminal to the negative terminal on a single battery.
As this varies for different Apple devices, no single answer can be given. Read the labeling as it will tell the actual voltage.
I assume you have a 30 amp two pole 220 volts breaker. Check the voltage source. If the source voltage is 220V, but out let voltage is 120 then the breaker must be faulty, a high resistance or partial open circuit could have caused the reduced voltage at the breaker outlet.
To read 277 volts on a meter, simply ensure the meter is set to the appropriate voltage scale (typically AC). Then, connect the meter leads to the circuit or outlet you are measuring. The display should show the voltage reading, which in this case would be 277 volts. Be sure to take appropriate safety precautions when working with electricity.
A fully charged car battery will read 12.6 volts, 75% charge will read 12.4 volts, 50% charge will read 12.2 volts, and a 25% charged battery will read 12.0 volts with the engine not running. With the engine running it will read 13.5 to 15.5 volts.
The typical answer is current is zero when there is a break in the circuit. It depends on the complexity of the circuit, there may be other paths for the current to flow, such that if there is a break in one part of the circuit, the rest of the circuit still has current flow (but a different value than designed). If you are reading voltage, and there is a break then that will change, also depending on the complexity. If it is a single loop, and you're reading voltage before the break, your voltmeter will read the same voltage as the voltage source, since there is no current flowing between any resistors between the meter and the source. If you're reading voltage after the break then the meter will read zero (0) volts.
To check volts on a multimeter, set the dial to the voltage setting, connect the red probe to the positive terminal and the black probe to the negative terminal of the circuit or component you want to measure. Read the voltage displayed on the multimeter screen.
Yes, a battery with only a 25% charge will read 12 volts. A fully charged battery will read 12.6 volts.