View Full Version : Digital Multi-Meter question

12-27-2006, 09:17 PM

I have a circuit that I need to measure the current. I understand that the way to measure this current with a DMM would be to open the circuit and place the test leads in between the open circuit. Of course, the DMM would have to be set for the amp meter and the leads must be attached to the amp terminals of the DMM first and foremost.

The expected current will only be around 200uA and the meter can handle 400mA. My only concern is that this signal in my circuit is rated at 1200VDC. Can I actually make this measurement with my DMM? My DMM is rated up to 1000V, but that rating is for when the DMM is used to measure voltage and not current.

Can my DMM handle this 1200VDC when it is in AMP meter mode?

Thanks in advanced for all your help.


12-28-2006, 01:05 PM
1200 volts are lethal!!! Take great precautions at these voltages.

Short answer: No, it cannot handle 1200V if its rated 1000V.

Voltage rating is not just the ability to measure, its also about the breakdown voltages of the fuse, circuits, test leads insulation etc.

Instead of using the DMM as a uAmmeter, you could connect a known shunt (small resistance) in series with the current path, and measure the voltage across it. Then do some maths with Ohm's law to get the current value.

Not knowing what lies in your circuit, I cannot suggest what value of shunt to use.

Put that shunt on the ground side of the current loop. Although both leads will not have a potential difference of 1200V, but mind you, you may still be at lethal voltages even with this approach.

Hope this helps,
Mohit Mahajan.