Multimeter

[cfherd]

I just bought an electrical test meter as I thought it would be useful tool to have around the house for future electrical projects. Problem is I expected the instructions to be a little more concise.

I understand I always need the black probe plugged into Common and the red probe to either AC or DC depending on the circuit I am testing but it doesn't indicate how you should use them.

For example, say I wanted to establish if a wire in a light switch was live I assume the red probe would go to the wire I think was live but where do I put the black probe? To the black wire of the same line?

This is probably a stupid questions but hopefull somone can help.

Thanks

 

[ban-all-sheds]

Is there such a thing as a stupid question?

Anyway..

For example, say I wanted to establish if a wire in a light switch was live I assume the red probe would go to the wire I think was live but where do I put the black probe? To the black wire of the same line?

No - because that wire will either be floating, or live as well, there'll be no real potential difference between them.

You could measure the voltage between one of the live conductors and earth, assuming you know that the earth is connected.

I expected the instructions to be a little more concise.

Don't you mean less concise?

Try the external links here: http://en.wikipedia.org/wiki/Multimeter

 

[EdwardCurrent]

Hello Cfherd.

Before you get your new meter out of the box it may be a good idea to fully understand how basic domestic circuits are wired. Have a look in the wikki.
Re read the manual a few times and it might make some more 'sense'. (Remember, one wrong twist of that dial and the meter gets it !!)

All the best

Ed

 

[Anteaus]

I just bought an electrical test meter as I thought it would be useful tool to have around the house for future electrical projects. Problem is I expected the instructions to be a little more concise.

Thanks

Multimeters are fairly complex, and you will need to gain some experience of using it in order to understand all of its functions.

Perhaps the most important point is never to put the prods ACROSS a supply when the meter is on any current (Amps) range. This will cause a short, and may damage the meter. Only put the prods across live-neutral or live-earth on a suitable AC Volts range.

The Ohms range can be used to check continuity of a cable, but only with the power OFF. This in fact is one of the most useful aspects of a multimeter as it in many cases allows you to trace faults safely with the power off. If it has an audible indicatior, even better as you can hear this when connecting a cable at a remote location.

If your main requirement is personal safety (ensuring that circuits are isolated before working on them) then I prefer the humble neon tester, or a test lamp (a 15W bulb soldered to two meter prods) as these are simpler devices and less likely to misinterpreted.

Whatever test device you use, it is necessary to confirm that the tester itself is working (by checking a live circuit and observing the reading) before putting it to the supposedly-dead circuit. Otherwise if the meter/neon/bulb is faulty you may be in for an unpleasant surprise.

Hope this helps.

 

[breezer]

why not buy a battery, some cable, and a small lamp (12v?) you can wire that to mains switches and see how its done, you will need an inline fuse just in case though