Of course current flows in the voltmeter, how else could it work? The better the quality of the instrument, the lower current it needs for full scale deflection, hence the less effect it has on the circuit measured.
Even a 4 quid multimeter will have an input impedance in the mega Ohm range. The inaccuracies due the the meter impedance and measurement leads is vanishingly small and completely swamped by the specified accuracy of the shunt resistor and voltmeter.
Depends on what you are trying to measure.
If it is the voltage in an electronic device, it may draw more current than the device. If it was a washing machine, then neither here nor there.
You have to understand the limitations of your equipment.
In the days when moving coil meters were the norm, allowance had to be made for the loading of the meter on the measurement. If this was a problem, you'd use a valve voltmeter with a high input impedance - an expensive device. Modern DVMs have a similar high input impedance for pennies. And in general don't need an any allowance made when measuring.
What is more of a problem in practice is a high impedance meter will read mains voltages where there is no actual connection - caused by capacitive/inductive coupling. A moving coil meter which draws more current shows near zero.
In the end I followed a different route - and on advice here got myself a nice used Megger AC/DC Clamp Meter DCM2039 off eBay for under £30.
I can always sell it after the job ... but I'm sure I'll find and excuse to keep it.
Analogue meters are much lower R than that. Good ones are usually 50k/V, cheapies more like 1/10th that.
NT
cheapies more like 1/10th that.
Ive yet to see one much less than 20kohm/V
cheapies more like 1/10th th
The OP was attempting to measure 100Amps.
By putting a 5K Ohm resistor in parallel with a 0.01 Ohm shunt resistor the effective shunt resistance changes by 0.0002%. This is completely swamped by the accuracy of the shunt resistor and voltmeter.
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