On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote:

> On 2/07/2020 10:41 pm, Ralph Mowery wrote:
>> In article <rdjsa6$28b$1@reader1.panix.com>, presence@MUNGEpanix.com
>> says...
>>>
>>> Have you run this test with AC? That seems to be where the wheels come
>>> off. I brought up this thread to a friend and he mentioned his quest to
>>> repair some sort of HP true RMS meter that uses a thermocouple and heater
>>> to properly measure complex waveforms. I can't even guess how slow such a
>>> meter might be.
>>>
>>>> I had 3 or 4 of the Harbor Freight 'free' multimeters. The ones that
>>>> usually sell for around $ 5. They seem to be reasonable accurate for
>>>> the money. Plenty accurate for the home user to test things around the
>>>> house. I do admit that the safety issue of putting them across the 120
>>>> or 240 volt power wires is somewhat doubtful. I sure would not use one
>>>> where I worked to put across the 480 volt 3 phase system that is fused
>>>> with 200 amps.
>>>
>>> I'm pretty timid with anything upstream from a plain outlet. I had an
>>> edison base fuse burst in my hand once. Never seen one come apart before.
>>> It was just a 120v lighting circuit, but right off the service panel..
>>> There's way more excitement near those things.
>>>
>>>
>>
>> I have not ran any tests for AC . The things I work with don't care
>> about very much about being accurate to more than around 5 %. Usually
>> it is more of do I have a voltage/current or not.
>>
>> When I work on most anything other than low voltage (below 100 volts) I
>> ues either my Simpson 260 analog meter or a Fluke meter that is rated
>> for cat 3 and 4. If you have not heard of the Cat numbers, they are for
>> devices used in different power circuits. I don't know the numbers off
>> hand, but it goes something like this, Cat 1 is for low voltage items,
>> Cat 2 for things like stoves and refrigerators, Cat 3 for homw
>> wiring,and Cat 4 for the very high power circuits like I often worked on
>> like the 480 volt AC and 300 amps.
>>
>> For a real scare you should see some of the safety movies that Fluke put
>> out. They show under test conditions what can hapen to inexpensive
>> meters and their meters under different conditions like having the
>> meter set for amps and putting across a 480 volt circuit that has plenty
>> of amps .
>>
> Ahh the old "Leaving it on amps" trick. How many of us can say they
> never did it ?

I find it crazy that you can select volts and have the wires in the amps holes. The switch should change the contacts. I've broken a meter doing that, just measuring the voltage on a car battery. £100 meter, but UNFUSED FFS! At least the mA range was fused, but they couldn't be bothered putting in a 20A fuse for the big range....

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
> On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote:
>
>> On 2/07/2020 10:41 pm, Ralph Mowery wrote:
>>> For a real scare you should see some of the safety movies that
>>> Fluke put out. They show under test conditions what can hapen to
>>> inexpensive meters and their meters under different conditions like
>>> having the meter set for amps and putting across a 480 volt circuit
>>> that has plenty of amps .
>>>
>> Ahh the old "Leaving it on amps" trick. How many of us can say they
>> never did it ?
>
> I find it crazy that you can select volts and have the wires in the
> amps holes. The switch should change the contacts. I've broken a
> meter doing that, just measuring the voltage on a car battery. £100
> meter, but UNFUSED FFS! At least the mA range was fused, but they
> couldn't be bothered putting in a 20A fuse for the big range....

The separate amps jacks exist for at least two reasons:

1) If the range switch also switched in/out the current shunt, then the
user could accidentally create a short circult across the probe tips
simply by turning the range switch to or across the amps measurement
ranges. Even if they were quickly turning /across/ the amps settings
ranges, a brief short circuit would be created, which would cause
damage to the meter as well as the device under test depending upon
what was connected at the time.

2) By having the amps jacks separate, the range switch itself does not
have to have contacts beefy enough to carry the current for the amps
settings. Remember, when measuring amps, the current being measured
flows *through* the meter itself. This would require very different
(and likely much more expensive) range switch contacts.

Some meters do have sensors for the amps jacks that sound an alarm if
the probes are inserted in the amps jacks but the range switch is on a
different setting than amperes.

On Fri, 17 Jul 2020 15:02:16 +0100, Rich <rich@example.invalid> wrote:

> In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
>> On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote:
>>
>>> On 2/07/2020 10:41 pm, Ralph Mowery wrote:
>>>> For a real scare you should see some of the safety movies that
>>>> Fluke put out. They show under test conditions what can hapen to
>>>> inexpensive meters and their meters under different conditions like
>>>> having the meter set for amps and putting across a 480 volt circuit
>>>> that has plenty of amps .
>>>>
>>> Ahh the old "Leaving it on amps" trick. How many of us can say they
>>> never did it ?
>>
>> I find it crazy that you can select volts and have the wires in the
>> amps holes. The switch should change the contacts. I've broken a
>> meter doing that, just measuring the voltage on a car battery. £100
>> meter, but UNFUSED FFS! At least the mA range was fused, but they
>> couldn't be bothered putting in a 20A fuse for the big range....
>
> The separate amps jacks exist for at least two reasons:
>
> 1) If the range switch also switched in/out the current shunt, then the
> user could accidentally create a short circult across the probe tips
> simply by turning the range switch to or across the amps measurement
> ranges. Even if they were quickly turning /across/ the amps settings
> ranges, a brief short circuit would be created, which would cause
> damage to the meter as well as the device under test depending upon
> what was connected at the time.

Then you put the amps ranges on one end of the dial. You would never go through them. And what idiot turns the dial while it's connected?!

> 2) By having the amps jacks separate, the range switch itself does not
> have to have contacts beefy enough to carry the current for the amps
> settings. Remember, when measuring amps, the current being measured
> flows *through* the meter itself. This would require very different
> (and likely much more expensive) range switch contacts.

Or a relay.

> Some meters do have sensors for the amps jacks that sound an alarm if
> the probes are inserted in the amps jacks but the range switch is on a
> different setting than amperes.

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
> On Fri, 17 Jul 2020 15:02:16 +0100, Rich <rich@example.invalid> wrote:
>
>> In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
>>> On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote:
>>>
>>>> On 2/07/2020 10:41 pm, Ralph Mowery wrote:
>>>>> For a real scare you should see some of the safety movies that
>>>>> Fluke put out. They show under test conditions what can hapen to
>>>>> inexpensive meters and their meters under different conditions like
>>>>> having the meter set for amps and putting across a 480 volt circuit
>>>>> that has plenty of amps .
>>>>>
>>>> Ahh the old "Leaving it on amps" trick. How many of us can say they
>>>> never did it ?
>>>
>>> I find it crazy that you can select volts and have the wires in the
>>> amps holes. The switch should change the contacts. I've broken a
>>> meter doing that, just measuring the voltage on a car battery. £100
>>> meter, but UNFUSED FFS! At least the mA range was fused, but they
>>> couldn't be bothered putting in a 20A fuse for the big range....
>>
>> The separate amps jacks exist for at least two reasons:
>>
>> 1) If the range switch also switched in/out the current shunt, then the
>> user could accidentally create a short circult across the probe tips
>> simply by turning the range switch to or across the amps measurement
>> ranges. Even if they were quickly turning /across/ the amps settings
>> ranges, a brief short circuit would be created, which would cause
>> damage to the meter as well as the device under test depending upon
>> what was connected at the time.
>
> Then you put the amps ranges on one end of the dial. You would never
> go through them.

Some meters have range switches that rotate through a full 360 degrees
with no stops - there would be no "end of the dial" in those instances.

And even with an 'end of the dial' there is still the possibility of
landing 'off by one' while turning the dial.

> And what idiot turns the dial while it's connected?!

The same idiot who'd leave the leads plugged into the amps jacks and
then attempt to measure the voltage of a car battery (or some other low
impedance high current voltage source).

I suspect you would find changing the range switch while connected is
much more common than your response implies. Esp. for switching
up/down a range for meters that are not auto-ranging.

>> 2) By having the amps jacks separate, the range switch itself does not
>> have to have contacts beefy enough to carry the current for the amps
>> settings. Remember, when measuring amps, the current being measured
>> flows *through* the meter itself. This would require very different
>> (and likely much more expensive) range switch contacts.
>
> Or a relay.

Which also equates directly to added expense vs. having the user
themselves be that "relay". And for battery powered meters, shorter
battery life (due to the current consumed by the relay coil).

It is also possible (this is a guess in my part) that the CAT ratings
specify separate amps jacks for an added safety factor of "user must
deliberately move lead to obtain short circuit through meter".

As well, the user who'd leave the leads plugged into amps, and then try
to measure voltage on car battery or other high current source is also
just as likely to leave the range switch in the amps setting (after
having measured current somewhere) and subsequently try to measure
voltage. It is not possible to fully protect users who don't pay
attention from doing stupid things. Either they forget to unplug from
the amps jack, or they forget to switch away from the amps range,
either way they get a local fireworks display of their own doing.

On Fri, 17 Jul 2020 21:26:15 +0100, Rich <rich@example.invalid> wrote:

> In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
>> On Fri, 17 Jul 2020 15:02:16 +0100, Rich <rich@example.invalid> wrote:
>>
>>> In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org..jp> wrote:
>>>> On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong..com> wrote:
>>>>
>>>>> On 2/07/2020 10:41 pm, Ralph Mowery wrote:
>>>>>> For a real scare you should see some of the safety movies that
>>>>>> Fluke put out. They show under test conditions what can hapen to
>>>>>> inexpensive meters and their meters under different conditions like
>>>>>> having the meter set for amps and putting across a 480 volt circuit
>>>>>> that has plenty of amps .
>>>>>>
>>>>> Ahh the old "Leaving it on amps" trick. How many of us can say they
>>>>> never did it ?
>>>>
>>>> I find it crazy that you can select volts and have the wires in the
>>>> amps holes. The switch should change the contacts. I've broken a
>>>> meter doing that, just measuring the voltage on a car battery. £100
>>>> meter, but UNFUSED FFS! At least the mA range was fused, but they
>>>> couldn't be bothered putting in a 20A fuse for the big range....
>>>
>>> The separate amps jacks exist for at least two reasons:
>>>
>>> 1) If the range switch also switched in/out the current shunt, then the
>>> user could accidentally create a short circult across the probe tips
>>> simply by turning the range switch to or across the amps measurement
>>> ranges. Even if they were quickly turning /across/ the amps settings
>>> ranges, a brief short circuit would be created, which would cause
>>> damage to the meter as well as the device under test depending upon
>>> what was connected at the time.
>>
>> Then you put the amps ranges on one end of the dial. You would never
>> go through them.
>
> Some meters have range switches that rotate through a full 360 degrees
> with no stops - there would be no "end of the dial" in those instances..

Then don't make them like that.

> And even with an 'end of the dial' there is still the possibility of
> landing 'off by one' while turning the dial.

Then have a gap which is connected to nothing.

>> And what idiot turns the dial while it's connected?!
>
> The same idiot who'd leave the leads plugged into the amps jacks and
> then attempt to measure the voltage of a car battery

Wrong. You adjust the dial to what you want to do, not remembering what you were measuring yesterday. Having only one thing to change makes it way easier to get it right.

> (or some other low impedance high current voltage source).

It only has to get over 20 amps to fuck the meter.

> I suspect you would find changing the range switch while connected is
> much more common than your response implies. Esp. for switching
> up/down a range for meters that are not auto-ranging.

Meters should always auto range. Mine all do, and I've never even considered adjusting the dial while it's connected. I'm not going to change between resistance, current, and volts and want to leave it connected to the same thing.

>>> 2) By having the amps jacks separate, the range switch itself does not
>>> have to have contacts beefy enough to carry the current for the amps
>>> settings. Remember, when measuring amps, the current being measured
>>> flows *through* the meter itself. This would require very different
>>> (and likely much more expensive) range switch contacts.
>>
>> Or a relay.
>
> Which also equates directly to added expense vs. having the user
> themselves be that "relay".

No, because you save on an extra socket.

> And for battery powered meters, shorter
> battery life (due to the current consumed by the relay coil).

Latching relays use very little indeed, like the one in my room thermostat. 2 AA batteries last years.

> It is also possible (this is a guess in my part) that the CAT ratings
> specify separate amps jacks for an added safety factor of "user must
> deliberately move lead to obtain short circuit through meter".

Then they're fools, because now "user can obtain short circuit by forgetting he was measuring current yesterday, or because a colleague was without him knowing". If it was selected on the dial, there is no possibility to make a mistake. You select what you want and that's what you get. It's illogical to have one thing pointing at volts while another thing is expecting current!

Anyway, a simple fuse would solve all this. All you lose if you make a mistake is a fuse, not the internal workings of the meter, the test leads, the thing you're testing, and possibly your face.

> As well, the user who'd leave the leads plugged into amps, and then try
> to measure voltage on car battery or other high current source is also
> just as likely to leave the range switch in the amps setting (after
> having measured current somewhere) and subsequently try to measure
> voltage.

Nope. I pick up a multimeter and set it to what I'm about to measure. Same way as I don't drive into my house because I left my car in forward gear yesterday.

> It is not possible to fully protect users who don't pay
> attention from doing stupid things. Either they forget to unplug from
> the amps jack, or they forget to switch away from the amps range,
> either way they get a local fireworks display of their own doing.

People make mistakes. The best equipment prevents this. My VW Golf for example would not allow me to select 1st gear when going 100mph. It was quite clever in fact. I could do that on purpose and it would drop one gear at a time to slow the car as quickly as possible to assist the brakes in an emergency. And yes I did try it a few times, one time I scared the shit out of the passenger (who had never seen an automatic gearbox before).

In article <ret1h6$stk$1@dont-email.me>, rich@example.invalid says...
>
> I suspect you would find changing the range switch while connected is
> much more common than your response implies. Esp. for switching
> up/down a range for meters that are not auto-ranging.
>
> >> 2) By having the amps jacks separate, the range switch itself does not
> >> have to have contacts beefy enough to carry the current for the amps
> >> settings. Remember, when measuring amps, the current being measured
> >> flows *through* the meter itself. This would require very different
> >> (and likely much more expensive) range switch contacts.
> >
> > Or a relay.
>
> Which also equates directly to added expense vs. having the user
> themselves be that "relay". And for battery powered meters, shorter
> battery life (due to the current consumed by the relay coil).
>
> It is also possible (this is a guess in my part) that the CAT ratings
> specify separate amps jacks for an added safety factor of "user must
> deliberately move lead to obtain short circuit through meter".
>
> As well, the user who'd leave the leads plugged into amps, and then try
> to measure voltage on car battery or other high current source is also
> just as likely to leave the range switch in the amps setting (after
> having measured current somewhere) and subsequently try to measure
> voltage. It is not possible to fully protect users who don't pay
> attention from doing stupid things. Either they forget to unplug from
> the amps jack, or they forget to switch away from the amps range,
> either way they get a local fireworks display of their own doing.
>
>
>

I often leave the leads connected to a Simpson 260 and change voltage
ranges. Where I worked there were so many wires in a conduit carrring
120 VAC control voltage it was difficult to tell if the voltage was
'real' or induced by the coupling. I found out that if I started on the
500 volt range and then switched to the 250 volt range if the meter
pointer stayed in the same relative position I could then switch to the
50 volt range and the meter pointer would still be near the same
relative position if the voltage was induced. If the pointer changed
positions to follow the 120 VAC when going to the 250 volt scale the
voltage was real.

I doubt that the CAT rating requies seperate Amps positions for the
leads. Fluke uses special fuses in their meters to get the CAT ratings.
They do not have a seperate jack for the ohms settings either which is
more likely where the meter would be set. Most of the time the
circuit would have to be broken and the meter inserted to measuer amps.

As you say it is impossiable to fully protect everyone from doing
somethen forgetful or stupid, but having a $ 300 meter instead of a $ 5
dollar one goes a long ways.

I do have a Fluke test meter that is purty much fool proof up to 600
volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
wire through the prongs. It does have a switch for voltage and ohms. I
have on purpose set it to ohms and put it across a fuse in a 480 volt AC
circuit to see if the fuse is good or bad. No problem to do this.

On Fri, 17 Jul 2020 23:07:43 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote:

> In article <ret1h6$stk$1@dont-email.me>, rich@example.invalid says...
>>
>> I suspect you would find changing the range switch while connected is
>> much more common than your response implies. Esp. for switching
>> up/down a range for meters that are not auto-ranging.
>>
>> >> 2) By having the amps jacks separate, the range switch itself does not
>> >> have to have contacts beefy enough to carry the current for the amps
>> >> settings. Remember, when measuring amps, the current being measured
>> >> flows *through* the meter itself. This would require very different
>> >> (and likely much more expensive) range switch contacts.
>> >
>> > Or a relay.
>>
>> Which also equates directly to added expense vs. having the user
>> themselves be that "relay". And for battery powered meters, shorter
>> battery life (due to the current consumed by the relay coil).
>>
>> It is also possible (this is a guess in my part) that the CAT ratings
>> specify separate amps jacks for an added safety factor of "user must
>> deliberately move lead to obtain short circuit through meter".
>>
>> As well, the user who'd leave the leads plugged into amps, and then try
>> to measure voltage on car battery or other high current source is also
>> just as likely to leave the range switch in the amps setting (after
>> having measured current somewhere) and subsequently try to measure
>> voltage. It is not possible to fully protect users who don't pay
>> attention from doing stupid things. Either they forget to unplug from
>> the amps jack, or they forget to switch away from the amps range,
>> either way they get a local fireworks display of their own doing.
>
> I often leave the leads connected to a Simpson 260 and change voltage
> ranges. Where I worked there were so many wires in a conduit carrring
> 120 VAC control voltage it was difficult to tell if the voltage was
> 'real' or induced by the coupling. I found out that if I started on the
> 500 volt range and then switched to the 250 volt range if the meter
> pointer stayed in the same relative position I could then switch to the
> 50 volt range and the meter pointer would still be near the same
> relative position if the voltage was induced. If the pointer changed
> positions to follow the 120 VAC when going to the 250 volt scale the
> voltage was real.

Better to use something that draws bit of current, like one of those screwdrivers that lights a neon through your capacitance.

> I doubt that the CAT rating requies seperate Amps positions for the
> leads. Fluke uses special fuses in their meters to get the CAT ratings.
> They do not have a seperate jack for the ohms settings either which is
> more likely where the meter would be set. Most of the time the
> circuit would have to be broken and the meter inserted to measuer amps.
>
> As you say it is impossiable to fully protect everyone from doing
> somethen forgetful or stupid, but having a $ 300 meter instead of a $ 5
> dollar one goes a long ways.
>
> I do have a Fluke test meter that is purty much fool proof up to 600
> volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
> wire through the prongs. It does have a switch for voltage and ohms. I
> have on purpose set it to ohms and put it across a fuse in a 480 volt AC
> circuit to see if the fuse is good or bad. No problem to do this.

With a bad fuse it doesn't blow up?

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
> On Fri, 17 Jul 2020 21:26:15 +0100, Rich <rich@example.invalid> wrote:
>> As well, the user who'd leave the leads plugged into amps, and then
>> try to measure voltage on car battery or other high current source
>> is also just as likely to leave the range switch in the amps setting
>> (after having measured current somewhere) and subsequently try to
>> measure voltage.
>
> Nope. I pick up a multimeter and set it to what I'm about to
> measure. Same way as I don't drive into my house because I left my
> car in forward gear yesterday.

Interesting....

Yet you said this yesterday:

From: "Commander Kinsey" <CFKinsey@military.org.jp>
Date: Thu, 16 Jul 2020 20:09:20 +0100
Message-ID: <op.0nu3hup8wdg98l@glass>

....

I find it crazy that you can select volts and have the wires in the
amps holes. ... I've broken a meter doing that, just measuring the
voltage on a car battery. A £100 meter, but UNFUSED FFS!

....

One aspect of "set it to what I'm about to measure" should normally
include: "are the leads in the correct jacks".

In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says...
> I do have a Fluke test meter that is purty much fool proof up to 600
> > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
> > wire through the prongs. It does have a switch for voltage and ohms. I
> > have on purpose set it to ohms and put it across a fuse in a 480 volt AC
> > circuit to see if the fuse is good or bad. No problem to do this.
>
> With a bad fuse it doesn't blow up?
>
>

No it does not . It is designed to protect its self from voltage on the
ohms scale. They are only about $ 130

Even better is a quick tester by Fluke. it has 2 leads and about 8 or
so leds on it. Both it and the T1000 look similar to bannanas, even
yellow in color. The 2nd tester is fully automatic. Connect the two
leads to anything under 600 or so volts. If voltage, the leds light up
, the more for more voltage. Anoter is for AC or DC. If there is less
than about 200 ohms and no voltage, there is a led and buzzer for that.

About as fool proof as they make it for quick tests.

On Fri, 17 Jul 2020 23:37:07 +0100, Rich <rich@example.invalid> wrote:

> In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
>> On Fri, 17 Jul 2020 21:26:15 +0100, Rich <rich@example.invalid> wrote:
>>> As well, the user who'd leave the leads plugged into amps, and then
>>> try to measure voltage on car battery or other high current source
>>> is also just as likely to leave the range switch in the amps setting
>>> (after having measured current somewhere) and subsequently try to
>>> measure voltage.
>>
>> Nope. I pick up a multimeter and set it to what I'm about to
>> measure. Same way as I don't drive into my house because I left my
>> car in forward gear yesterday.
>
> Interesting....
>
> Yet you said this yesterday:
>
> From: "Commander Kinsey" <CFKinsey@military.org.jp>
> Date: Thu, 16 Jul 2020 20:09:20 +0100
> Message-ID: <op.0nu3hup8wdg98l@glass>
>
> ...
>
> I find it crazy that you can select volts and have the wires in the
> amps holes. ... I've broken a meter doing that, just measuring the
> voltage on a car battery. A £100 meter, but UNFUSED FFS!
>
> ...
>
> One aspect of "set it to what I'm about to measure" should normally
> include: "are the leads in the correct jacks".

No, because it's illogical to change two things to set one thing.

On Sat, 18 Jul 2020 00:10:49 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote:

> In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says...
>> I do have a Fluke test meter that is purty much fool proof up to 600
>> > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
>> > wire through the prongs. It does have a switch for voltage and ohms. I
>> > have on purpose set it to ohms and put it across a fuse in a 480 volt AC
>> > circuit to see if the fuse is good or bad. No problem to do this.
>>
>> With a bad fuse it doesn't blow up?
>>
>>
>
> No it does not . It is designed to protect its self from voltage on the
> ohms scale. They are only about $ 130

Howe does it measure ohms and distinguish its own current from the current from the circuit? That's if you're testing a DC circuit.

> Even better is a quick tester by Fluke. it has 2 leads and about 8 or
> so leds on it. Both it and the T1000 look similar to bannanas, even
> yellow in color. The 2nd tester is fully automatic. Connect the two
> leads to anything under 600 or so volts. If voltage, the leds light up
> , the more for more voltage. Anoter is for AC or DC. If there is less
> than about 200 ohms and no voltage, there is a led and buzzer for that.
>
> About as fool proof as they make it for quick tests.

Does it check for current if there's no voltage?

In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says...
>
> > I do have a Fluke test meter that is purty much fool proof up to 600
> > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
> > wire through the prongs. It does have a switch for voltage and ohms. I
> > have on purpose set it to ohms and put it across a fuse in a 480 volt AC
> > circuit to see if the fuse is good or bad. No problem to do this.
>
> With a bad fuse it doesn't blow up?
>
>

No, it is designed to protect its self.

In article <op.0nw9prwrwdg98l@glass>, CFKinsey@military.org.jp says...
>
> > About as fool proof as they make it for quick tests.
>
> Does it check for current if there's no voltage?
>
>

Just how can there be curent if there is no voltage ?

There is no current by the leads, but works like a clamp on meter to
check for AC Current. Does not do DC current.

There can be voltage but no current.

In sci.electronics.basics Ralph Mowery <rmowery28146@earthlink.net> wrote:
> In article <ret1h6$stk$1@dont-email.me>, rich@example.invalid says...
>>
>> I suspect you would find changing the range switch while connected is
>> much more common than your response implies. Esp. for switching
>> up/down a range for meters that are not auto-ranging.
>>
>> >> 2) By having the amps jacks separate, the range switch itself does not
>> >> have to have contacts beefy enough to carry the current for the amps
>> >> settings. Remember, when measuring amps, the current being measured
>> >> flows *through* the meter itself. This would require very different
>> >> (and likely much more expensive) range switch contacts.
>> >
>> > Or a relay.
>>
>> Which also equates directly to added expense vs. having the user
>> themselves be that "relay". And for battery powered meters, shorter
>> battery life (due to the current consumed by the relay coil).
>>
>> It is also possible (this is a guess in my part) that the CAT ratings
>> specify separate amps jacks for an added safety factor of "user must
>> deliberately move lead to obtain short circuit through meter".
>>
>> As well, the user who'd leave the leads plugged into amps, and then try
>> to measure voltage on car battery or other high current source is also
>> just as likely to leave the range switch in the amps setting (after
>> having measured current somewhere) and subsequently try to measure
>> voltage. It is not possible to fully protect users who don't pay
>> attention from doing stupid things. Either they forget to unplug from
>> the amps jack, or they forget to switch away from the amps range,
>> either way they get a local fireworks display of their own doing.
>>
>>
>>
>
> I often leave the leads connected to a Simpson 260 and change voltage
> ranges. Where I worked there were so many wires in a conduit carrring
> 120 VAC control voltage it was difficult to tell if the voltage was
> 'real' or induced by the coupling. I found out that if I started on the
> 500 volt range and then switched to the 250 volt range if the meter
> pointer stayed in the same relative position I could then switch to the
> 50 volt range and the meter pointer would still be near the same
> relative position if the voltage was induced. If the pointer changed
> positions to follow the 120 VAC when going to the 250 volt scale the
> voltage was real.

The simpson meters are interesting in that they have as many jacks as they
they positions on the switch. You really need to move the leads around all
the time to do anything. I guest it makes you think, a little. I did catch
myself reading the ohms range wrong though recently.
> I doubt that the CAT rating requies seperate Amps positions for the
> leads. Fluke uses special fuses in their meters to get the CAT ratings.
> They do not have a seperate jack for the ohms settings either which is
> more likely where the meter would be set. Most of the time the
> circuit would have to be broken and the meter inserted to measuer amps.
>
> As you say it is impossiable to fully protect everyone from doing
> somethen forgetful or stupid, but having a $ 300 meter instead of a $ 5
> dollar one goes a long ways.
>
> I do have a Fluke test meter that is purty much fool proof up to 600
> volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
> wire through the prongs. It does have a switch for voltage and ohms. I
> have on purpose set it to ohms and put it across a fuse in a 480 volt AC
> circuit to see if the fuse is good or bad. No problem to do this.

I just got one of those clamp current multimeters. I noticed some glaring
limitations vs the full out Fluke 87 V, but at the same time, it's way
more "idiot-proof".

The current ranges, even for DC at only available though the current
clamp. It's just not possible to short anything out with the test probes.
The downside (not really surprising) is no low current ranges. Ok fine.
The input impedance is pretty low at 1Meg as well, but for poking at line
voltage wiring, this is fine. Again, no matter what range you are set it,
it appears to be impossible to blow up the meter as it has no low
resistance across the leads modes. The ohms range seems to max out at 40k
or something surprisibly low like that, again, no big deal for prodding at
lighting circuits or an outlet, or some 24 volt circuit.

Getting all sorts of wonky reading with the banana jack type K
thermocouple though. It seems the meter has an internal thermometer and it
compares to the junction at the end of the probe. Not really sure how that
all works and how the temperatures of the banana jacks affect things as
they are not the special metals in the leads of the probe. I know with
normal process controllers, and deviation of the correct connector or
metals used will result in really strange readings.

In sci.electronics.basics Ralph Mowery <rmowery28146@earthlink.net> wrote:
> In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says...
>> I do have a Fluke test meter that is purty much fool proof up to 600
>> > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
>> > wire through the prongs. It does have a switch for voltage and ohms. I
>> > have on purpose set it to ohms and put it across a fuse in a 480 volt AC
>> > circuit to see if the fuse is good or bad. No problem to do this.
>>
>> With a bad fuse it doesn't blow up?
>>
>>
>
> No it does not . It is designed to protect its self from voltage on the
> ohms scale. They are only about $ 130
>
> Even better is a quick tester by Fluke. it has 2 leads and about 8 or
> so leds on it. Both it and the T1000 look similar to bannanas, even
> yellow in color. The 2nd tester is fully automatic. Connect the two
> leads to anything under 600 or so volts. If voltage, the leds light up
> , the more for more voltage. Anoter is for AC or DC. If there is less
> than about 200 ohms and no voltage, there is a led and buzzer for that.
>
> About as fool proof as they make it for quick tests.

Hmm, Remeber those neon voltage testers with two leads and the bizarre
shirt pocket clip? I had one go out on me, showed no voltage when there
was some. Whoops.

Now I use one of those ground/wiring testers. I figure it will still light
up if one neon indicator fails.

In article <rf8eq6$brr$1@reader1.panix.com>, presence@MUNGEpanix.com
says...
> I do have a Fluke test meter that is purty much fool proof up to 600
> > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a
> > wire through the prongs. It does have a switch for voltage and ohms. I
> > have on purpose set it to ohms and put it across a fuse in a 480 volt AC
> > circuit to see if the fuse is good or bad. No problem to do this.
>
> I just got one of those clamp current multimeters. I noticed some glaring
> limitations vs the full out Fluke 87 V, but at the same time, it's way
> more "idiot-proof".
>
> The current ranges, even for DC at only available though the current
> clamp. It's just not possible to short anything out with the test probes.
> The downside (not really surprising) is no low current ranges. Ok fine.
> The input impedance is pretty low at 1Meg as well, but for poking at line
> voltage wiring, this is fine. Again, no matter what range you are set it,
> it appears to be impossible to blow up the meter as it has no low
> resistance across the leads modes. The ohms range seems to max out at 40k
> or something surprisibly low like that, again, no big deal for prodding at
> lighting circuits or an outlet, or some 24 volt circuit.
>
>

Meters like the T1000 are for quick go or no go test mainly. For what
they are mainly used for it does not make any differnece if they are off
by even 10 %. For quick tests in an industrial enviroment it does not
matter if the control voltage is 115.25 volts when anything from around
110 to 130 volts is close enough. Most circuits will have less than
1000 ohms resistance , many of the motors will show up as an almoat
short if the windings are good. Fuses are almost shorts or opens.

The Fluke 87 and meters like that are more for electronic tests. The
specs on them are very good and will be accurate to one or two decimal
places.

When I worked I had access to almost any kind of meter or test set. I
often grabbed my Simpson 260 and analog Ampprobe for the equipment that
would not start or run. However I would stick the Fluke 'Bananna' in my
pocket to check some things like the fuses in a power circuit.

For the instruments where they needed to be measured to less than 1 %
out came the fluke 87 or more likely a special piece of equipment that
has a Heart interface. That reads signals on the instrument lines.

In article <rf8f20$brr$2@reader1.panix.com>, presence@MUNGEpanix.com
says...
>
> Hmm, Remeber those neon voltage testers with two leads and the bizarre
> shirt pocket clip? I had one go out on me, showed no voltage when there
> was some. Whoops.
>
> Now I use one of those ground/wiring testers. I figure it will still light
> up if one neon indicator fails.
>
>
>

Yes, I used one very often. One learns to put the leads across a source
that should have voltage on it to see if the neon bulb lights up, then
put it to the point to test and if the neon does not light up, go back
to a point that should have voltage on it.

Bad thing about where I worked there was so many wires in conduit that
the neon would light up even if there was no 'real' voltage on the wire.
Just induced voltage that if put under much of a load at all will seem
to diaspear.
It is still enough to shock the crap out of you, especially if wet with
sweat.

On Sat, 18 Jul 2020 00:30:22 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote:

> In article <op.0nw9prwrwdg98l@glass>, CFKinsey@military.org.jp says...
>>
>> > About as fool proof as they make it for quick tests.
>>
>> Does it check for current if there's no voltage?
>
> Just how can there be curent if there is no voltage ?
>
> There is no current by the leads, but works like a clamp on meter to
> check for AC Current. Does not do DC current.
>
> There can be voltage but no current.

I meant does it automatically work out if you want to test for current or voltage?