A tip for current measurement with DMM ?

[N Cook]

Can anyone improve on the following especially reducing, even further, the
chance of mistakingly using a meter set for current monitoring on live kit ,
thinking you are measuring voltage.

Assuming others here are like me, rarely use the current function of a
DVM/DMM.
Leave a gummy bright or contrasting sticker over the ammeter socket of the
meter. When transfering the red lead to that socket then transfer the label
to the function or on/off switch.

The ideal would be some sort of mechanical interlock but I cannot see how.

 

[Dave Plowman (News)]

Can anyone improve on the following especially reducing, even further,
the chance of mistakingly using a meter set for current monitoring on
live kit , thinking you are measuring voltage.

Assuming others here are like me, rarely use the current function of a
DVM/DMM. Leave a gummy bright or contrasting sticker over the ammeter
socket of the meter. When transfering the red lead to that socket then
transfer the label to the function or on/off switch.

The ideal would be some sort of mechanical interlock but I cannot see
how.

My Fluke says 'lead' on the display when you change. Hasn't stopped me
blowing a fuse though. ;-)

 

[William Sommerwerck]

Some DMMs -- such as my Fluke -- have a beeper that sounds when the switch
is set to measure voltage, but the cables are plugged into the current
jacks. (The opposite situation doesn't need a warning.)

 

[Reinhard Zwirner]

Can anyone improve on the following especially reducing, even further, the
chance of mistakingly using a meter set for current monitoring on live kit ,
thinking you are measuring voltage.

Assuming others here are like me, rarely use the current function of a
DVM/DMM.
Leave a gummy bright or contrasting sticker over the ammeter socket of the
meter. When transfering the red lead to that socket then transfer the label
to the function or on/off switch.

The ideal would be some sort of mechanical interlock but I cannot see how.

Hi,

Have a look at

<www.gmc-instruments.com/english/produkte/metrahi2.htm>

This DMM (obviously discontinued) and other types of that line
of GMC DMMs have a so called "Automatic Blocking System":
depending on the measuring range only the corresponding inputs
can be used - the other ones are blocked.

I don't know if Gossen Metrawatt's DMMs still have this feature.

HTH

Reinhard

 

[Meat Plow]

My Fluke says 'lead' on the display when you change. Hasn't stopped me
blowing a fuse though. ;-)

Same here. I've blown a few fuses in my 77.

 

[N Cook]

Same here. I've blown a few fuses in my 77.

Its not the blowing of a meter fuse that I'm concerned about. Its shorting
some expensive bit of otherwise working kit that I'm wary of.
I've not done it for a long time but there could so easily be some time in
the future, probably pushed for time, and there will be a big flash and a
bang.

 

[Ron(UK)]

Its not the blowing of a meter fuse that I'm concerned about. Its shorting
some expensive bit of otherwise working kit that I'm wary of.
I've not done it for a long time but there could so easily be some time in
the future, probably pushed for time, and there will be a big flash and a
bang.

I am in the happy position of having several decent meters, one of which
I use exclusively for current measurements. It has croc clip leads.

It`s very rare that my favourite Flukey gets switched to amps - So
there`s your answer, buy another meter just for current, fit it with
croc clips to remind you do to go poking around circuit boards with it

Ron(UK)

 

[N Cook]

how.

Hi,

Have a look at

<www.gmc-instruments.com/english/produkte/metrahi2.htm>

This DMM (obviously discontinued) and other types of that line
of GMC DMMs have a so called "Automatic Blocking System":
depending on the measuring range only the corresponding inputs
can be used - the other ones are blocked.

I don't know if Gossen Metrawatt's DMMs still have this feature.

HTH

Reinhard

I take it the 2 red rings on the lower line are shutters that slide away
when the probe plug is pushed into the relevant socket.

It still leaves the possibility of thinking (or not thinking) that the DMM
is , per usual, set for measuring voltage but is still set for current.

So far, the only retrofit add on I can think of, is a buzzer activated on
inserting the probe plug in the current socket and beeps continuously until
removed.

 

[N Cook]

I am in the happy position of having several decent meters, one of which
I use exclusively for current measurements. It has croc clip leads.

It`s very rare that my favourite Flukey gets switched to amps - So
there`s your answer, buy another meter just for current, fit it with
croc clips to remind you do to go poking around circuit boards with it

Ron(UK)

That seems the easiest solution, with permanent blanking off the current
sockets of the one used for Vac & dc ,R , and D test only. I will see if my
old Beckman or whatever it is is still working order.

 

[Eeyore]

Can anyone improve on the following especially reducing, even further, the
chance of mistakingly using a meter set for current monitoring on live kit ,
thinking you are measuring voltage.

Assuming others here are like me, rarely use the current function of a
DVM/DMM.
Leave a gummy bright or contrasting sticker over the ammeter socket of the
meter. When transfering the red lead to that socket then transfer the label
to the function or on/off switch.

The ideal would be some sort of mechanical interlock but I cannot see how.

Some Fluke models beep at you if you select a voltage range with the probe still
plugged into the current socket.

Graham

 

[Reinhard Zwirner]

I take it the 2 red rings on the lower line are shutters that slide away
when the probe plug is pushed into the relevant socket.

AFAIK the input sockets for measuring current are blocked mechanically
when the function/range selector is switched to voltage or resistance
measurement (and vice versa): it isn't possible to insert test leads
into the blocked sockets.

At the same time you can't switch to voltage (or resistance)
measurement if the test leads are still plugged into the current
measurement sockets.

It still leaves the possibility of thinking (or not thinking) that the DMM
is , per usual, set for measuring voltage but is still set for current.

No, it wouldn't be possible to turn the function/range selector switch
to any voltage measurement range.

So far, the only retrofit add on I can think of, is a buzzer activated on
inserting the probe plug in the current socket and beeps continuously until
removed.

IMHO this wouldn't be necessary any more.

Regards

Reinhard

 

[N Cook]

AFAIK the input sockets for measuring current are blocked mechanically
when the function/range selector is switched to voltage or resistance
measurement (and vice versa): it isn't possible to insert test leads
into the blocked sockets.

At the same time you can't switch to voltage (or resistance)
measurement if the test leads are still plugged into the current
measurement sockets.


No, it wouldn't be possible to turn the function/range selector switch
to any voltage measurement range.


IMHO this wouldn't be necessary any more.

Regards

Reinhard

The point of my post/query was that someone, like me, using the same DMM day
in day out, 99.99 percent of the time for other than current, may accidently
go to use this meter , still set in amps mode, for measuring volts , just
because it is so ingrained in using it for such purposes.

Anyway, potential pitfall solved using Ron(UK) technique in this thread.

 

[N Cook]

I am in the happy position of having several decent meters, one of which
I use exclusively for current measurements. It has croc clip leads.

It`s very rare that my favourite Flukey gets switched to amps - So
there`s your answer, buy another meter just for current, fit it with
croc clips to remind you do to go poking around circuit boards with it

Ron(UK)

A 5 minute job and peace of mind.
Fluke 77 with hot melt glue down the 2 current sockets and a dollop on the
rotating function switch surround. so it cannot be turned to A dc or ac.

A dollop of hotmelt in the "volts" socket of the old meter and a 2 croc-clip
ended leads. instead of probes, so very unlikely to absent-mindedly use use
that one in volts test mode.

 

[Ron(UK)]

A 5 minute job and peace of mind.
Fluke 77 with hot melt glue down the 2 current sockets and a dollop on the
rotating function switch surround. so it cannot be turned to A dc or ac.

A dollop of hotmelt in the "volts" socket of the old meter and a 2 croc-clip
ended leads. instead of probes, so very unlikely to absent-mindedly use use
that one in volts test mode.

Or just use some pvc tape, avoid ruining a meter, neater and cheaper, or
if you want an elegant solution, you can buy blanking plugs in red and
black to fit 4mm banana sockets.


Ron(UK)

 

[Sam Goldwasser]

Some DMMs -- such as my Fluke -- have a beeper that sounds when the switch
is set to measure voltage, but the cables are plugged into the current
jacks. (The opposite situation doesn't need a warning.)

Actually, it might. If you have leads plugged into the voltage inputs
and are attempting to measure current in a high voltage system such as
a laser power supply, the DMM will likely smoke when power is turned on.

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subject line. Or, you can contact me via the Feedback Form in the FAQs.

 

[Jamie]

Can anyone improve on the following especially reducing, even further, the
chance of mistakingly using a meter set for current monitoring on live kit ,
thinking you are measuring voltage.

Assuming others here are like me, rarely use the current function of a
DVM/DMM.
Leave a gummy bright or contrasting sticker over the ammeter socket of the
meter. When transfering the red lead to that socket then transfer the label
to the function or on/off switch.

The ideal would be some sort of mechanical interlock but I cannot see how.

What are you saying? You blew up your meter?
Get a industrial fluke.

 

[Ryan Weihl]

What are you saying? You blew up your meter?
Get a industrial fluke.

but have you considred a clamp-on probe to measure current.
Fluke makes one, forgot model nbr, matches to a particular meter.
The output would be a voltage you can measure with the DMM
that prevented us blowing ddm when measuring currents

--

 

[Ross Herbert]

:Can anyone improve on the following especially reducing, even further, the
:chance of mistakingly using a meter set for current monitoring on live kit ,
:thinking you are measuring voltage.
:
:Assuming others here are like me, rarely use the current function of a
VM/DMM.
:Leave a gummy bright or contrasting sticker over the ammeter socket of the
:meter. When transfering the red lead to that socket then transfer the label
:to the function or on/off switch.
:
:The ideal would be some sort of mechanical interlock but I cannot see how.


Gossen Metrawatt meters have the interlock function. If you have the RED lead in
the normal V/Ohms socket the current measurement sockets are blanked off with a
red plate. You can't select the current ranges on the range switch until the RED
lead is unplugged. If you have the RED lead in one of the current measuring
sockets (mA or A) the range switch can't be moved to any other position. Of
course this doesn't stop you from trying to measure voltage while it is set up
for current measurement but I find that I always check for range setting before
connecting to equipment and because the switch won't move to any other position
this has always prevented mishaps.

 

[Dave Plowman (News)]

but have you considred a clamp-on probe to measure current.
Fluke makes one, forgot model nbr, matches to a particular meter.
The output would be a voltage you can measure with the DMM
that prevented us blowing ddm when measuring currents

But just how accurate are they when measuring small DC current?

 

[James Sweet]

Can anyone improve on the following especially reducing, even further, the
chance of mistakingly using a meter set for current monitoring on live kit
,
thinking you are measuring voltage.

Assuming others here are like me, rarely use the current function of a
DVM/DMM.
Leave a gummy bright or contrasting sticker over the ammeter socket of the
meter. When transfering the red lead to that socket then transfer the
label
to the function or on/off switch.

The ideal would be some sort of mechanical interlock but I cannot see how.

I use the current measurement frequently, the only time I've had trouble is
going back to voltage measurement after using current and even then it's
rare and results only in a blown fuse.