Multimeter Question

I can't see a problem with that. When measuring voltage, the multimeter's internal resistance is very high, so it will not be able to cause a short.

Any chance you had your multimeter accidently set for current measurement in stead of voltage?

Some multimeters need the positive test lead to be moved to a different socket for current measurements. These will cause a short even if the dial is set for voltage measurement.

Any chance that the meter was setup for current (amperage) measurement?

It should be just fine. Like Robert and Rich, I suspect you had the meter set up for current measurements. Or you had some other fault that was causing a short.

If the meter is rated for AC at line voltage (and most multimeters are) then it should work just fine.

"Rob Snyder"

Most of the cheaper meters ( analogue and digital display ) and most older models are quite unsuitable for testing AC mains supply voltages and high voltages in general - cos they are simply not safe.

A safe meter has at least got plugs on the leads that are shrouded, adequate fusing in the current ranges and a battery compartment that cannot just pop open. It also does not have sockets on the top you can plug small components into.

It must also be free of serious defects when used with high voltages - like the display freezing when you apply a probe.

Hobbyists tend to own meters that have some or all these safety problems.

... Phil

Phil Allis>[...]A safe meter[...]does not have sockets on the top

Running down my own list in my head, I'd overlooked that one. Now I wonder *where* the sparks were (at the far end of the leads, or at the meter).

So yes, as much as I was about to swear that something else was going on, it was simply that I had the red lead in the slot for measuring current, not voltage. Sparks were at the motor, not at the meter. It's an old Radio Shack digital multimeter... at least fifteen if not twenty years old, but has always worked well. Amazingly, I did not do any permanent damage to the meter, the motor, or my person.

Many thanks for all the replies, and for forcing me to go back and validate what I was doing rather than blame something else. Lesson learned.

You probably blew the fuse in that current input - the rest of the meter will still work, but if you attempt to measure current using that input, the meter will be open-circuit.

I have seen cheap meters that only fuse the mA position, the 10A or

Like those three-buck-fifty meters that Jan and Joerg were recently enthusing over :-)

It says in the manual not to use them on mains circuits. this is probalbly one of the reasons.

"Peter Bennett"

Lotsa cheap DMMs have no fuse in the 10 amp current range and rely on fuses and breakers in the test circuit to open.

Such meters are not safe on high current ( ie industrial ) AC or DC circuits - cos the leads can explode in the operator's face.

... Phil

I've got an MPEG of a similar meter being tested at VDE. Lots of smoke and flames. Leads in current position. I'd post it to a.b.s.e. but, since the OP uses Google, there's not much point.