Choosing the highest setting on your ammeter from the outset will prevent you from blowing the meter’s internal fuse if the amperage is too high. [2] X Research source Battery powered circuits run on DC. Other power supplies may be AC or DC, and some can alternate between both. Check the power supply manual or label to determine its current type. [3] X Research source
The resistance reading of your ammeter will be indicated on a display on the front of the meter. You may have to adjust the power range before it can read the low level of a working fuse. Most ammeter fuses can be easily replaced or reset, though this process will vary according to your brand and model. Consult your ammeter’s manual to learn how to fix blown fuses. If you adjusted the power range lower to check the fuse, reset the range to its maximum to prevent the fuse from blowing when taking the actual amperage.
The ammeter will be tied into the circuit at this break so that electricity passes through the meter on its way to the item being powered, allowing the meter to take a reading. You may be able to “break” your circuit by loosening the fasteners connecting wiring to the power source’s negative ( - ) terminal or at the power input for the item receiving power. If you can’t create a break in the circuit at the negative ( - ) terminal or power input, you can cut, strip, and then resplice the wire.
Most ammeters use color coding to indicate positive and negative ends of a circuit. This may be different from country to country, but in many cases, red will represent positive and black negative. [5] X Research source The most commonly used ammeters have clamps that allow them to easily attach to wires. [6] X Expert Source Jesse KuhlmanMaster Electrician Expert Interview. 30 June 2020. Other models may use metal probes that you’ll wrap the wire around. You can also simply hold the leads of your ammeter to the bare wires of the broken circuit. Prevent exposed wire from touching anything while the circuit is engaged. [7] X Research source Be sure to only test one wire at a time. [8] X Expert Source Jesse KuhlmanMaster Electrician Expert Interview. 30 June 2020.
Depending on the strength of the circuit you’re testing, you may need to reduce the range for the power gauge until the display registers activity. Bare wires shouldn’t touch anything while the circuit is powered. Doing so could cause the circuit to short, an electrical fire, or a false reading. [10] X Research source
Because of the way electricity is distributed in a circuit, if you clamp two different wires together, it will throw off the meter’s reading. [13] X Research source
