Multimeter false readings

[Bradley6969]

Friend had a multimeter, not a very dear one just £30, was testing an outside light and said he tested the whole light inside belled everything out and tested the ballast which has built in ignitor and came to use his multimeter and it’s coming up with weird readings could this be why?

 

[Dannyg8810]

That makes no sense to me what so ever?????

 

[Des 56]

We would need to know what type of test he was making ,what instrument and function and then know the readings to make any worthwhile comment Bradley

 

[Pete999]

What exactly was your friend testing : resistance, Voltage, current, continuity, what did he have The meter set to when he was testing, it could be the meter was set at the wrong scale to do this testing, What was the reason for testing? was the outside light not working.
Your friend should be aware, as you should also, poking around in an electric fitting is inherently dangerous, and it needs to be said, should he be doing this work, because it sounds as though neither you or your friend have any electrical experience, sorry for the lecture.

 

[westward10]

Our friend Bradley is an apprentice and has a few threads on fault finding and the AM2.

 

[Pete999]

Our friend Bradley is an apprentice and has a few threads on fault finding and the AM2.

I did wonder if he was the same Bradley.

 

[Bradley6969]

He’s an apprentice and I’ve just qualified he was doing continuity test and checking voltage but I seem to think he tried doing a continuity test while the power was still on I wasn’t with him just how he’s explained to me

 

[Pete999]

I did wonder if he was the same Bradley.

Here you go Brad

 

[Des 56]

If he is doing live testing whilst being unsure of those tests,be a good idea never to loan him your own equipment just yet

 

[Bradley6969]

If he is doing live testing whilst being unsure of those tests,be a good idea never to loan him your own equipment just yet

Yes I agree good job he wasn’t with me I guess haha

 

[DavidSpark]

I actually wonder what people get taught in college. Inspection and testing was drummed in to me. The sequence of tests and how to do them safely, what insurentments to use and why the tests are carried out.

Anyone, working within the electrical industry with a few years under their belt should be able to explain and talk through testing, including a newly fully qualified electrician.

 

[Pete999]

Here you go Brad

I'm assuming you meant Multi meter and not Multi Function Tester

 

[Jay Sparks]

I always steer apprentices away from using a multi meter but they have to use one for their AM2, when doing fault finding. Which I find strange as most colleges won't/don't teach them how to use one, except maybe on electronics etc.

Although, I do own one and have used it myself for certain things/reasons but I like to think I am confident/competent enough to use it correctly, without harming myself or any ewuipment.lol

Jay

 

[Lucien Nunes]

In the days of the AVO 8 and similar, testing continuity with the power on would likely destroy the meter beyond economical repair in a fraction of a second. That would cost a couple of months wages for an apprentice (not that they would normally be allowed to use a meter of that calibre) so people were more careful and made sure they knew what test they were doing and why, before putting the probes on. Nowadays people poke around with total disregard.

Now, does your mate know what voltage a discharge lamp ignitor outputs when striking a lamp? If he did, maybe he would have thought twice about poking around even with a cheap meter. It can be up to about 3000V. Food for thought eh?

Anyway, you can sometimes get funny readings when checking high-voltage transformers for continuity even with the power off. Tiny induced currents in the primary can produce sufficient output from the secondary to confuse the meter. The same is true with highly inductive ballasts and chokes - the meter sees enough noise voltage and ringing that it can't properly measure its own test current, so you see readings jumping around and going out of range.

 

[PEG]

^ Spot on,there does seem to be a lack of teaching,regarding Multimeters,without which,i would not be able to take on,the tasks i do.

In the OP's post,he mentioned "belling out the whole inside..."

The term "belling out",would be restricted to simple wiring/switching,and the internal components,would be subjected to a series of specific tests,with possible separation/isolation,of individual components.

To be honest,the number of posts on here,usually by learners,DIY or hobbyists,who have spent 30-50 squid on a multimeter,and only use it for AC/DC,bit of continuity,etc,would be far better,to spend the same money on decent, approved voltage tester,which even if it did not offer other possible functions,is easy to learn how to find,what is most likely to cause harm

I have an old Megger TPT,which has AC/DC,Ohms measurement...even an RCD trip function,which together with a penknife,could find a lot of faults...if you only wore swimming trunks at work