My multimeter only has one 400mA fuse protecting the µA and mA range (and a 10A fuse protecting the amp range.) Is it possible to damage the microamp range by feeding milliamps through it?


1 Answer 1


Multimeters use a precision shunt resistor to measure current indirectly (known R, measure V, calculate I). Typically a low current range (uA to low mA) will have a larger resistance shunt resistor to generate a larger voltage drop.

As a result, this larger resistance is no longer negligible at higher currents and begins to cause a measurable voltage drop. Additionally, the power dissipation can begin to cause resistance change and eventually it will kill the resistor. Typically, a fast-blow fuse protects the shunt resistor from continuous over-current.

If you're wondering if running 10mA through the meter while in uA mode will damage it, the answer is most likely "no". If you run 300+ mA through the meter, then you will probably be in danger of blowing the fuse. If you try to use the meter as a volt-meter and forget to switch the leads, and connect it to a supply capable of dumping a lot of instantaneous power, you might be able to blow the shunt resistor before the fuse blows.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.