How to use multimeter

[alifrank1]

I hope someone can help!

My husband died 6 months ago and since then various things have gone wrong in the house. We were both great DIYers so I have quite a bit of knowledge. I managed to rewire my broken vacuum and have just replaced an extractor fan in the bathroom.

My problem is making sure the current is off! With the extractor fan, I just turned off the lighting circuit, but was aware that I should have been able to test it first. We have a mutimeter, but I don't know how to test to see if current is live.

Can anyone point me in the right direction please?

 

[andy]

Can anyone point me in the right direction please?

yes.

 

[Hotwire]

Instead of learning the use of a multimeter why not invest in a "neon screwdriver" its one handed operation so you will never be put in the unsafe situation of maybe getting a belt across the chest. Definately not recommended. The shaft of the screwdriver is insulated to keep your fingers safe and all you need do is place the blade on the wire to test and touch the end cap. Simple, light on power on, light of power of.

Here,s an example


http://www.tlc-direct.co.uk/Main_Index/Test_Meters_Index/Screwdrivers_4/

 

[andy]

Instead of learning the use of a multimeter why not invest in a "neon screwdriver" its one handed operation so you will never be put in the unsafe situation of maybe getting a belt across the chest. Definately not recommended. The shaft of the screwdriver is insulated to keep your fingers safe and all you need do is place the blade on the wire to test and touch the end cap. Simple, light on power on, light of power of.

Here,s an example


http://www.tlc-direct.co.uk/Main_Index/Test_Meters_Index/Screwdrivers_4/[/QUOTE]

DO NOT USE THEM. they are unreliable and should only be used as a screwdriver

 

[Nijinski001]

Fully agree.
I'm always suspicious of testers and always double check witha volt meter.
Bought a neon tester a few weeks ago to replace one that I lost.. It worked for teh afternoon I bought it. The following day I went to the same job. Switched the circuit off. Went to the JB and tested the live. Did the job. Went to a second circuit I know was live. Stuck the neon tester in. Nothing!!
Checked with a volt meter and guess what. 230V. Now that can give you a bolt across the chest!!

 

[slippyr4]

3 replies and noone actually answered her question!

You need to switch the multimeter to measuring volts. The markings on the dial signify the maximum voltage you can properly record at that setting. You should pick the next highest setting from 240v - on many multimeters this is 600v.

You need to ensure it's set to measure AC volts, not DC. Sometimes there is a small switch - AC or DC, and sometimes the dial will have separate ranges for AC volts and DC volts (often marked VAC or ACV or DCV etc).

Once you've picked the correct range, carefully touch the red probe on something that ought to be live, and touch the black probe on something that should be neutral. If the power is still on, then you'll see a reading that could be anything between 220 and 250 volts ish. These would be normal readings.

Do take the utmost care when testing- if something *is* still live, you don't want to hurt yourself when testing it.

Wherever possible, it makes sense to switch of the supply to the entire installation when doing any service work. Then you can be sure that even if there's some strange wiring going on, you're safe.

cheers

slip

 

[andy]

3 replies and noone actually answered her question!

because there are loads of other threads on the same thing

 

[ban-all-sheds]

Someone (breezer??) knows/used to know of a link to a "multimeters 101" website, with excellent diagrams...

 

[ebee]

Instead of learning the use of a multimeter why not invest in a "neon screwdriver" its one handed operation so you will never be put in the unsafe situation of maybe getting a belt across the chest. Definately not recommended. The shaft of the screwdriver is insulated to keep your fingers safe and all you need do is place the blade on the wire to test and touch the end cap. Simple, light on power on, light of power of.

Here,s an example


http://www.tlc-direct.co.uk/Main_Index/Test_Meters_Index/Screwdrivers_4/[/QUOTE]

Who the hell would make themselves part of an electrical circuit.
Neon mains testers are a NO NO

 

[Hotwire]

Well my neon must be the exception then, ive been using it for years. Meters fail too, especially the cheap ones. I have two Fluke meters one of which i used when i done a lot of auto electrics, i measured across the terminals of a car battery one day and got no reading. I bought a new meter battery thinking it was that, still no reading. It turned out one of the leads was broken internally which wasnt obvious till investigated, so good job i wasnt trusting its reading wile measuring 240volt. As someones said turn everything of if your not sure.

 

[ban-all-sheds]

But that problem you describe would have been immediately obvious, on car electrics or house wiring, if you had used the meter properly and verified that it was working before relying on what it told you.

If you'd got into trouble measuring a 240V circuit when it wasn't working it would have been 100% down to you not for following the proper procedures.

 

[Hacman]

Fluke volt sticks are more reliable than a neon screwdriver, very handy for just checking for a live. However always best to check with a meter as well, or check on a known supply first and after with the stick.

 

[Hotwire]

Doesnt make any difference wether i tested the meters functionality or not, if the wire was breaking it could have done it between self testing and testing the battery or whatever.

 

[alifrank1]

ok, thank you all for your answers, you have been very informative.

Sorry andy, I couldn't find the right thread to answer my question, hence posting it.

One more question please?

Because I was so worried when I'd turned the electricity off last time, I feel I want to have a practise with the multimeter before the next disaster strikes. What would be the safest and easiest equipment to try the multimeter on, whilst it is live? (yes, I do know that you are meant to turn the electric off, but then I won't know if I am doing what I am meant to be doing). I just feel I want to test something to make sure I am doing it right.

 

[Softus]

Sorry if I'm butting in here, but the thing I'm finding odd is that each of you seems to swear by a particular piece of test equipment.

What happened to the idea of risk reduction? There are no certainties where Volts are concerned, just the high probability that introducing an air gap will stop them from making the leap.

Personally, I use the following process of risk reduction (when working on 240VAC):

1. Wave an MK inductive tester at the live part to be worked on - verify that it lights up.

2. Isolate, preferably in two places (e.g. consumer unit and a local switch).

3. Wave the tester again, and verify that it doesn't light up and that I've therefore got the right isolator.

4. Expose the live parts to be worked on.

5. Switch back on again after warning everyone to stay away.

6. Test with both the MK tester and a standard neon screwdriver.

7. Isolate again.

8. Test again with both the MK tester and a standard neon screwdriver.

9. Brush my hand, with the briefest of contact, against any live part that I'm going to be in danger of touching by accident.

When did I last get a belt? The last time I didn't do all of the above.