Multimeter hazard The HOLD button

[bernardgreen]

One of my multimeters has a hold function. This freezes the reading on screen. It is said that it saves having to write the value down while holding probes onto terminals.

It is a hazard, Helping a friend to diagnose why his oil fired boiler was not working I got zero volts across the Live - Neutral supply to the boiler PCB. So clear why the boiler wasn't working.

But for some reason I double checked and then noticed the HOLD button on the meter was on. There was 230 volts on the probes but the meter was "holding" the zero volt value that was on the probes when the HOLD button was pressed accidently and un-noticed.

So if your multimeter has a hold button check the hold function is not operating, especially if you are using the meter to test for dead prior to working on the circuit or equipment.

 

[JohnW2]

Yes, it's a hazard of which one needs to be aware. Meters I have which have a 'hold' function put a prominent indication in the display when it is in 'hold' mode, but in some cases that indication is by a symbol, which users unfamiliar with the meter might not understand.

Kind Regards, John

 

[DetlefSchmitz]

This is one good reason why are encouraged to have a dedicated dead testing instrument, which doesn't have these dangers. I certainly do, and take its use quite seriously these days.

 

[JohnW2]

This is one good reason why are encouraged to have a dedicated dead testing instrument, which doesn't have these dangers. I certainly do, and take its use quite seriously these days.

That certainly makes good sense.

Wherever possible, I find it most reassuring is to 'see' (in my case hear) the voltage on the circuit I'm going to be working on 'go away' when I operate the isolator (or whatever). Accordingly, many years ago I made up a little tester (with plug-in 'adapter leads' for plugging into sockets or lamp holders, or just 'test leads') which sounds a loud buzzer when power is applied. I connect that to the live circuit in question and then am able to hear the buzzer stop when I operate the isolator, even if it's in a different part of the house. I undertake traditional 'testing for dead' after that, but having 'heard the power go off' is, as I said, a very good preliminary reassurance!

Kind Regards, John

 

[KingboyD]

The one meter of mine that does have a hold button has a Peak Hold, so if its pressed it will show say 110V, then if you go to a 230V supply it will jump upto that & hold that figure, good idea really.

 

[AndyPRK]

My neon screw driver doesn't have a hold button thankfully.

 

[efiste2]

For a prove DEAD item, the good old Drummond Test Lamp is still the preferred choice. the new versions come with a tester.[/img]

 

[JohnW2]

For a prove DEAD item, the good old Drummond Test Lamp is still the preferred choice.

I essentially agree, and still often use mine. However, they present a problem if your 'testing for dead' procedure includes testing N-E, if you're working on a SP-'isolated' RCD-protected circuit!

Kind Regards, John

 

[333rocky333]

For a prove DEAD item, the good old Drummond Test Lamp is still the preferred choice.

I essentially agree, and still often use mine. However, they present a problem if your 'testing for dead' procedure includes testing N-E, if you're working on a SP-'isolated' RCD-protected circuit!

Kind Regards, John

Whys that john.
I had the type with the solenoid or whatever that vibrated and that tripped rcds, but i wasnt aware the test lamp ones were a problem.

 

[JohnW2]

However, they present a problem if your 'testing for dead' procedure includes testing N-E, if you're working on a SP-'isolated' RCD-protected circuit!

Whys that john. I had the type with the solenoid or whatever that vibrated and that tripped rcds, but i wasnt aware the test lamp ones were a problem.

If you've only got SP 'isolation' then any fairly low impedance connection between N & E (whether through a lamp or anything else) is likely to result in the RCD tripping if there are any loads on any of the other circuits protected by that RCD (and, as recently discussed, potentially even if there are largish loads on circuits not protected by the same RCD).

Kind Regards, John

 

[ban-all-sheds]

So if your multimeter has a hold button check the hold function is not operating, especially if you are using the meter to test for dead prior to working on the circuit or equipment.

Surely you'd notice when you applied it to a known good source to verify that it would correctly indicate live?

You don't just connect a tester to what you believe to be dead and decide that it really is because your tester doesn't say otherwise.

That said 1: A hold function ought to release after a while.

That said 2: JW2 - you really need to get a grip re this quotation mark nonsense.

 

[JohnW2]

Surely you'd notice when you applied it to a known good source to verify that it would correctly indicate live? ... You don't just connect a tester to what you believe to be dead and decide that it really is because your tester doesn't say otherwise.

I think the problem is that the hold button is quite often in a position which makes it very easy to press it unintentionally (and unknowingly) simply by holding or handling the meter (as one may well do whilst moving it from the known good source to the circuit under test) - I have a couple of clamp meters for which that is very much the case. In theory, that should usually (but not always, if the problem is repeated) be detected if, as one should, one goes back to the known source after testing one's circuit - but that's probably the part of the total procedure most likely to be (and most commonly) omitted/overlooked.

That said 1: A hold function ought to release after a while.

That would, indeed, be good, sensible, and easy to implement in an electronic meter - but I've never owned one which did that.

Kind Regards, John

 

[JohnW2]

That said 2: JW2 - you really need to get a grip re this quotation mark nonsense.

Nonsense is in the eye of the beholder, so I can't comment on that, but I doubt that my intended use of quotation marks has changed that much in the past 40+ years, so it's unlikely to change now.

Although I undoubtedly often accidentally veer from this intention, my intended convention is to use double quotes for actual quotations (or if there are apostrophes within text I want to put quotation marks around), and single quotation marks to indicate that (probably far often than I really should!) I am using a word or phrase in a manner slightly different/wider/whatever from its common/ usual/ strict/ dictionary meaning.

Kind Regards, John

 

[ban-all-sheds]

my intended convention is to use ... single quotation marks to indicate that (probably far often than I really should!) I am using a word or phrase in a manner slightly different/wider/whatever from its common/ usual/ strict/ dictionary meaning.

a 'hold' function
when it is in 'hold' mode

I find it most reassuring is to 'see' (in my case hear) the voltage on the circuit I'm going to be working on 'go away'
'adapter leads'
'test leads'
'testing for dead'
'heard the power go off'

'testing for dead'
'isolated'

'isolation'

'informative'
'rated'
'ideal'

'construction'
'future proofing'

plug has two flat 'prongs'
('speaker') plugs have one flat and one (small) round 'prong'

'first impression'
'shake off'

'thing'
'transformer'
'power supply'

'in' and 'out'.
'wired upside down'
'supply side'
'tripping'
'setting'

... a copious use of inverted commas. "I know this is not quite the right word", the inverted commas seem to say, "but I can't be bothered to think of a better"; or, "please note that I am using this word facetiously"; or, "don't think I don't know that this is a cliché". If the word is the right one, do not be ashamed of it: if it is the wrong one, do not use it.

 

[bernardgreen]

Can we have a hold on comments about how people use quotation marks. \Or start a new thread to discuss the matter

In almost all cases the meaning is understood whether it is ' ' or " " that are used.