This is a guide primarily aimed at analogue panel meters, volts and amps. Typically these meters do not need an external source of power to enable the meter to function. These meters draw a tiny amount of power from the circuit they are in.

Digital multimeters operate in a similar way, but they are usually powered by an internal battery. When using a digital multimeter to measure voltage or current, always check the test leads are in the correct sockets on the meter before connecting them to the circuit. Connecting a meter configured in ammeter mode directly across a voltage source will cause a near short circuit, possibly causing damage and blowing a fuse in your meter.

VOLTMETERS

  Symbol                   Connection Diagram

• Voltmeters measure Voltage.

• Voltage is measured in Volts, V.

• Voltmeters are connected in parallel across components.

• Voltmeters have a very high resistance.

• The positive terminal of the meter, marked + should be connected nearest to + on the    battery or power supply.

• The negative terminal of the meter, marked - should be connected nearest to - on the battery or power supply

AMMETERS

Symbol                       

• Ammeters measure current.

• Current is measured in amps (amperes), A.

• Ammeters are connected in series.

• To connect in series you must break the circuit and put the ammeter across the gap, as shown in the diagram.

• Ammeters have a very low resistance.

At the point in which you connect your meter in your circuit:

• The positive terminal of the meter, marked + should be connected nearest to + on the battery or power supply.

• The negative terminal of the meter, marked - should be connected nearest to - on the battery or power supply.