multimeter help

[plugwash]

so one minuite we are teilling people to get mutimeters the next you are saying you won't be able to useit properly anyway.

 

[swelec]

If people with no electrical knowledge ask for help with simple diy projects, for example changing an old light fitting or extending a ring main, where all work can be preceded by switching off all the power, then I believe they should be helped

If they have enough skills to fault find a wiring problem using a meter, but are stuck on a particular problem, again help should be forthcoming

People in the first category should not be encouraged to work on live equipment - that is my argument

Buy one if you know how to use it - if not then call in someone who will not potentially harm themselves working on live equipment

If i have a leaking radiator, I will ask for help to repair it

If I have a gas leak I will phone a heating engineer

 

[Panjandrum]

Swelec
I'm with you on this one. The best advice to this poster is probably to find someone who has the right expertise for the job.
What is often missed is the importance of judgement based on experience. An experienced DIYer with limited tools, who knows those limitations and their own, is much, much safer than someone without experience and common sense - however well-equipped.
I would be extremely worried about giving advice on how to use a meter when the initial post (perhaps wrongly) suggests a lack of basic knowledge.
Should we be worried that Dally hasn't posted since Sunday evening?
PJ

 

[GRC]

The best advice to this poster is probably to find someone who has the right expertise for the job. I would be extremely worried about giving advice on how to use a meter when the initial post (perhaps wrongly) suggests a lack of basic knowledge.

GRC - but he's trying to acquire the basic knowledge by asking people here; i.e. trying to find someone who has the right experience. Isn't he?

Regards, Graham

 

[Panjandrum]

I agree with GRC's sentiment but in the circumstances, given the content of the first post, I would not be happy giving advice to the poster about use of a meter unless I could actually be there to oversee what he was doing. If he was just looking for information maybe OK, but he is about to poke things into places that could do him damage.
Oh, by the way, "someone who has the right expertise for the job" could well be someone he knows who has practical experience and knows how to manage a n**n s*********r (DUCKING FOR COVER).

 

[ban-all-sheds]

I did physics O and A levels, and I've been an electronics hobbyist on and off (mostly off) for 35 years. It's been so long since I understood "Electricity 101" that I can't remember learning it, nor do I remember ever not knowing it.

I guess the problem I have is that I can't put myself into the mindset of someone who doesn't understand voltage, current and resistance. Not knowing how to wire a loop-in ceiling rose, or a 2-way switch I can understand and deal with, but not knowing the really basic stuff is like not knowing how to breathe - I don't see how it works.

If you tell someone to unscrew something, you expect that they know how to use a screwdriver, and how screws work, and I make the mistake of assuming that someone who doesn't have a multimeter is like someone who doesn't have a screwdriver, not someone who doesn't have a screwdriver because he doesn't know what screws are.

Does that make sense?

 

[Panjandrum]

BAS - I was just about to jump in and say it doesn't make sense when I read carefully. It does. But your response to others who do not have multimeters suggests the opposite of what you say on this thread - that you assume that someone who does not have a multimeter is like someone who knows diddlysquat about electricity.
I come from a similar history. And I worry in this case that although the poster does have a multimeter this cannot be taken to indicate any degree of competence. At that level, instruction without actually being there is, I think, extremely risky.

 

[breezer]

i have seen "people" using a dmm but all they know is that if it shows less than xx ohms "it must be ok" but they dont know why, it is scary

 

[oilman]

"what if the guy follows this and I have left out something vital, and as a result he gets injured "

C'est la vie. People don't get taught everything before they're allowed to take a motor vehicle on the road, and that's arguably much more dangerous.

I served a four year apprentiship and spent four years in college getting a HNC and sometimes wince when I read some of the questions asked here

As later in this topic, what's the problem? I learn't to use a multimeter at about 14. Bought second hand televisions and rigged them up, messed about with lights at about 9. Learnt that a finger in a light socket was b****y uncomfortable. Still hit my thumb with hammer now and again (Never served any apprenticeship!)

....got a multimeter but no instructions on how to use - BIN IT

Er,......why not give a little positive help? This is similar to ".....if you don't know what you're doin' mate, get someone who does." Thank goodness that the reason we know things nowadays is due to people who didn't give up quite so easily.

Buy one if you know how to use it - if not then call in someone who will not potentially harm themselves working on live equipment.

That appears to rule everyone out then.

 

[ban-all-sheds]

BAS - I was just about to jump in and say it doesn't make sense when I read carefully. It does. But your response to others who do not have multimeters suggests the opposite of what you say on this thread - that you assume that someone who does not have a multimeter is like someone who knows diddlysquat about electricity.

No - I may assume they know ds about electrical wiring etc, but not that they simply don't know what a volt or an ohm is, or that current flows in circuits and so on.

 

[swelec]

OK, what I expected

Some with me some against

I will take up one point oilman said " why not give a little positive help"

Here goes

A meter is a measuring instrument. An ammeter measures current, a voltmeter measures the potential difference (voltage) between two points, and an ohmmeter measures resistance. A multimeter combines these functions, and possibly some additional ones as well, into a single instrument.

Many household problems can be fault found using resistance and voltage measurements. Most DIY'ers will rarely need to measure current


Testing for Continuity ( resistance )

This test should be done when current is NOT present. Always unplug the device or turn off the main circuit breaker before attempting a continuity test.

A continuity test is done to determine whether a circuit is open or closed. To test the continuity of a circuit requires the use of a multimeter or multitester.

Set the multimeter to the ohm setting. The symbol for ohm is , the Greek letter omega. If there is more than one ohm setting, choose X1.

Note that while the probes are not touching anything, the multimeter will indicate a reading of infinity. A reading of infinity indicates that the circuit is open and cannot conduct current. When you touch the two probes together, the reading changes to zero. A reading of zero indicates that the circuit is closed and can conduct current. Touch each probe to one of the terminals (or poles) of the device. If the reading changes to zero the device has continuity.


To test a switch, place a probe on each pole of the switch. When you move the switch from the off to the on position, the meter reading should change from infinity to zero, which implies that the switch is working.

To measure current.

The circuit must be broken to allow the meter to be connected in series
ammeters must have a LOW resistance

Think about the changes you would have to make to a practical circuit in order to include the ammeter. To start with, you need to break the circuit so that the ammeter can be connected in series. All the current flowing in the circuit must pass through the ammeter. Meters are not supposed to alter the behaviour of the circuit, or at least not significantly, and it follows that an ammeter must have a very LOW resistance.


To measure potential difference (voltage)

The circuit is not changed the voltmeter is connected in parallel voltmeters must have a HIGH resistance

This time, you do not need to break the circuit. The voltmeter is connected in parallel between the two points where the measurement is to be made. ( ( betwwen live and neutral to check for mains supply) Since the voltmeter provides a parallel pathway, it should take as little current as possible. In other words, a voltmeter should have a very HIGH resistance.

Voltage measurements are used much more often than current measurements.

This is simplifying artcles which can be found using Google and typing in

How to use a multimeter

The originator of the thread has a problem with a flickering light

This means the supply to the lamp is intermittent

What can cause this

Loose wires - but where. It could be in the next room where the feed from one ceiling rose into the next rose comes from

It could be in the switch or the switch itself making intermittent contact

What about the light fitting itself

A flashing lamp could and many times does point to wear in the lamp holder itself

I would sugggest changing this before taking lessons on multimeters