Error of % + digits?...

[Cydrome Leader]

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:

On Sun, 12 Jul 2020 20:21:10 +0100, Tom Gardner <spamjunk@blueyonder.co.uk> wrote:

On 12/07/20 19:01, Pimpom wrote:
On 7/12/2020 11:15 PM, Commander Kinsey wrote:
On Fri, 26 Jun 2020 05:23:31 +0100, Cydrome Leader <presence@mungepanix.com
wrote:

In sci.electronics.equipment Pimpom <nobody@nowhere.com> wrote:

My mechanical slide caliper has a resolution of 0.001 inch. This
means that it can display measurements with a precision of 1 mil,

What if your caliper had a resolution of 1 mil +/- 3 counts on the last
digit?
.....<snip>........

In America, what is a \"mill\"? In the UK, it used to mean a thousandth of an
inch, but people use it to mean a millimetre nowadays.


It\'s not a mill. It\'s mil - single l. It means, and has always meant, a
thousandth of an inch. It\'s not an Americanism.

In the UK \"mill\" means millilitre.

If you want to refer to fractions of an inch, then
it is /always/ \"thou\", i.e. thousandths of an inch.

In the UK \"mil/mill\" /never/ means 0.001\".

Yes it does. My neighbour\'s a tradesman (in Scotland) and says
\"mill/mil\" (I don\'t know which as they sound the same in speech) as
shorthand for millimetre. As in \"that kitchen unit is 600 mill wide\".
Since we don\'t use inches for such things in the UK, there\'s no
confusion.

The context there is key too. While I\'d not measure a countertop or
whatever in millimeters, it would make no sense that anything in a kitchen
would be measured thicknesses of paper.

We (in the US) use \"guage\" for wire and sheet metal. We also use \"guage\"
for measuring really thin stuff like plastic films. In the last case, it\'s
a completly different unit, but with proper context won\'t confuse anybody.

Question for the metric woodworkers. Does anybody cut a piece of wood to
317mm or 429mm or other off numbers when building a house or handing a
door or installing a countertop?

 

[Commander Kinsey]

On Tue, 30 Jun 2020 16:09:46 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote:

In article <rdecuc$m73$1@reader1.panix.com>, presence@MUNGEpanix.com
says...

So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors?

might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
have been from a raffle or something like that.

The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
AC ranges which are \"1.2% RDG +10 Digits\". If I had new leads, I\'d trust it
with outlet voltage, but would stay away from 208volts. The meter has 3.5
digits or max display of 1999. I\'m figuring a real 100volt AC reading could
be 99 to 101 plus another error of +/- 1 volt for the 10 digits tolerance
on the display or count. so 100volts from your Japanese outlet reference
might read 98 to 102 volts. So while in the ballpark, it\'s better than you
can read off a Simpson 260 meter in the AC voltage range. I could be wrong
on this too.

It\'s a pretty decent meter for poking at DC circuits for the tens of
dollars is must have cost when new.

It seems that maybe due to modern manufactoring the meters are more
accurate than they were 20 years ago. I bought some DC voltmeters from
China. They display 3 digits. They read from 0 to 99.9 volts. I coulg
get 4 of them for less than $ 15 including the shipping. I hooked all 4
of them in parallel with a Fluke 87 . Three of them tracked right along
with the Fluke with the last digit sometimes being one high or low from
0 to 24 volts. The fourth one was off by an average of 2 on the last
digit. I found an adjustment screw on the back of the meter and tweaked
it and re ran the test. It then fell in line with the other meters.

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.

Whyever not? Even the cheap ones usually state you can use them up to 1000 volts. I\'ve used them on 240 and 415 just fine. I used one on 2000 volts once, and it just failed inside, not even smoke or noise.

 

[Commander Kinsey]

On Tue, 30 Jun 2020 16:09:46 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote:

In article <rdecuc$m73$1@reader1.panix.com>, presence@MUNGEpanix.com
says...

So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors?

might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
have been from a raffle or something like that.

The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
AC ranges which are \"1.2% RDG +10 Digits\". If I had new leads, I\'d trust it
with outlet voltage, but would stay away from 208volts. The meter has 3.5
digits or max display of 1999. I\'m figuring a real 100volt AC reading could
be 99 to 101 plus another error of +/- 1 volt for the 10 digits tolerance
on the display or count. so 100volts from your Japanese outlet reference
might read 98 to 102 volts. So while in the ballpark, it\'s better than you
can read off a Simpson 260 meter in the AC voltage range. I could be wrong
on this too.

It\'s a pretty decent meter for poking at DC circuits for the tens of
dollars is must have cost when new.

It seems that maybe due to modern manufactoring the meters are more
accurate than they were 20 years ago. I bought some DC voltmeters from
China. They display 3 digits. They read from 0 to 99.9 volts. I coulg
get 4 of them for less than $ 15 including the shipping. I hooked all 4
of them in parallel with a Fluke 87 . Three of them tracked right along
with the Fluke with the last digit sometimes being one high or low from
0 to 24 volts. The fourth one was off by an average of 2 on the last
digit. I found an adjustment screw on the back of the meter and tweaked
it and re ran the test. It then fell in line with the other meters.

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.

Whyever not? Even the cheap ones usually state you can use them up to 1000 volts. I\'ve used them on 240 and 415 just fine. I used one on 2000 volts once, and it just failed inside, not even smoke or noise.

 

[Commander Kinsey]

On Tue, 30 Jun 2020 04:52:44 +0100, Cydrome Leader <presence@mungepanix.com> wrote:

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
On Wed, 24 Jun 2020 21:06:04 +0100, Rich <rich@example.invalid> wrote:

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
On Thu, 18 Jun 2020 15:38:46 +0100, Pimpom <nobody@nowhere.com> wrote:

On 6/18/2020 6:33 PM, Commander Kinsey wrote:
I just bought an amp clamp meter, and it states the error is \"+/-
1.9% + 3 digits\". What does the \"3 digits\" part mean?


If your meter should read, say 1.875 A, the correct reading could
be anywhere from 1.872 to 1.878. This is a possible error in the
display presented to you in the analog-digital display conversion
process. The +/-1.9% possible error is about the measurement
taken including - but not only - any error made by the sensor.

Thanks, I wonder why all my other meters only list a % error. Is it
included within it somehow, or are they just lying, or do some meters
not have this error?

One generally finds the percentage plus digits error measures on more
expensive equipment. Less expensive equipment more often than not only
lists a percentage and nothing more.

So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors?

might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
have been from a raffle or something like that.

The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
AC ranges which are \"1.2% RDG +10 Digits\".

TEN!? Surely that\'s more than the number of digits it has? In which case it has no accuracy at all.

If I had new leads, I\'d trust it
with outlet voltage, but would stay away from 208volts.

You oughta complain about that low voltage. Some equipment needs at least 220.

 

[Commander Kinsey]

On Tue, 30 Jun 2020 04:52:44 +0100, Cydrome Leader <presence@mungepanix.com> wrote:

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
On Wed, 24 Jun 2020 21:06:04 +0100, Rich <rich@example.invalid> wrote:

In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote:
On Thu, 18 Jun 2020 15:38:46 +0100, Pimpom <nobody@nowhere.com> wrote:

On 6/18/2020 6:33 PM, Commander Kinsey wrote:
I just bought an amp clamp meter, and it states the error is \"+/-
1.9% + 3 digits\". What does the \"3 digits\" part mean?


If your meter should read, say 1.875 A, the correct reading could
be anywhere from 1.872 to 1.878. This is a possible error in the
display presented to you in the analog-digital display conversion
process. The +/-1.9% possible error is about the measurement
taken including - but not only - any error made by the sensor.

Thanks, I wonder why all my other meters only list a % error. Is it
included within it somehow, or are they just lying, or do some meters
not have this error?

One generally finds the percentage plus digits error measures on more
expensive equipment. Less expensive equipment more often than not only
lists a percentage and nothing more.

So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors?

might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
have been from a raffle or something like that.

The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
AC ranges which are \"1.2% RDG +10 Digits\".

TEN!? Surely that\'s more than the number of digits it has? In which case it has no accuracy at all.

If I had new leads, I\'d trust it
with outlet voltage, but would stay away from 208volts.

You oughta complain about that low voltage. Some equipment needs at least 220.

 

[Commander Kinsey]

On Thu, 02 Jul 2020 06:45:42 +0100, Cydrome Leader <presence@mungepanix.com> wrote:

In sci.electronics.equipment Ralph Mowery <rmowery28146@earthlink.net> wrote:
In article <rdecuc$m73$1@reader1.panix.com>, presence@MUNGEpanix.com
says...

So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors?

might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
have been from a raffle or something like that.

The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
AC ranges which are \"1.2% RDG +10 Digits\". If I had new leads, I\'d trust it
with outlet voltage, but would stay away from 208volts. The meter has 3.5
digits or max display of 1999. I\'m figuring a real 100volt AC reading could
be 99 to 101 plus another error of +/- 1 volt for the 10 digits tolerance
on the display or count. so 100volts from your Japanese outlet reference
might read 98 to 102 volts. So while in the ballpark, it\'s better than you
can read off a Simpson 260 meter in the AC voltage range. I could be wrong
on this too.

It\'s a pretty decent meter for poking at DC circuits for the tens of
dollars is must have cost when new.



It seems that maybe due to modern manufactoring the meters are more
accurate than they were 20 years ago. I bought some DC voltmeters from
China. They display 3 digits. They read from 0 to 99.9 volts. I coulg
get 4 of them for less than $ 15 including the shipping. I hooked all 4
of them in parallel with a Fluke 87 . Three of them tracked right along
with the Fluke with the last digit sometimes being one high or low from
0 to 24 volts. The fourth one was off by an average of 2 on the last
digit. I found an adjustment screw on the back of the meter and tweaked
it and re ran the test. It then fell in line with the other meters.

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.

How well do these things work measuring dodgy waves like from a cheap UPS or invertor?

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\'ve replaced outlets (240V, not the namby pamby USA stuff) without turning off the power - other outlets on the same circuit were being used in the office and I saw no point in interrupting them.

Just keep your fingers off the metal things and don\'t short stuff together. Wear goggles and gloves if you want to be a girl about it.

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.

Try shorting two phases together with 500A cables. That causes lots of smoke, a fire alarm, 3 fire engines, and a visit from the power company. Do not ever employ Irish electricians.

 

[Commander Kinsey]

On Thu, 02 Jul 2020 06:45:42 +0100, Cydrome Leader <presence@mungepanix.com> wrote:

In sci.electronics.equipment Ralph Mowery <rmowery28146@earthlink.net> wrote:
In article <rdecuc$m73$1@reader1.panix.com>, presence@MUNGEpanix.com
says...

So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors?

might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
have been from a raffle or something like that.

The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
AC ranges which are \"1.2% RDG +10 Digits\". If I had new leads, I\'d trust it
with outlet voltage, but would stay away from 208volts. The meter has 3.5
digits or max display of 1999. I\'m figuring a real 100volt AC reading could
be 99 to 101 plus another error of +/- 1 volt for the 10 digits tolerance
on the display or count. so 100volts from your Japanese outlet reference
might read 98 to 102 volts. So while in the ballpark, it\'s better than you
can read off a Simpson 260 meter in the AC voltage range. I could be wrong
on this too.

It\'s a pretty decent meter for poking at DC circuits for the tens of
dollars is must have cost when new.



It seems that maybe due to modern manufactoring the meters are more
accurate than they were 20 years ago. I bought some DC voltmeters from
China. They display 3 digits. They read from 0 to 99.9 volts. I coulg
get 4 of them for less than $ 15 including the shipping. I hooked all 4
of them in parallel with a Fluke 87 . Three of them tracked right along
with the Fluke with the last digit sometimes being one high or low from
0 to 24 volts. The fourth one was off by an average of 2 on the last
digit. I found an adjustment screw on the back of the meter and tweaked
it and re ran the test. It then fell in line with the other meters.

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.

How well do these things work measuring dodgy waves like from a cheap UPS or invertor?

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\'ve replaced outlets (240V, not the namby pamby USA stuff) without turning off the power - other outlets on the same circuit were being used in the office and I saw no point in interrupting them.

Just keep your fingers off the metal things and don\'t short stuff together. Wear goggles and gloves if you want to be a girl about it.

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.

Try shorting two phases together with 500A cables. That causes lots of smoke, a fire alarm, 3 fire engines, and a visit from the power company. Do not ever employ Irish electricians.

 

[Michael Terrell]

208 is a standard three phase voltage. It is three 120 volt lines phased 120 degrees apart.

 

[Michael Terrell]

208 is a standard three phase voltage. It is three 120 volt lines phased 120 degrees apart.

 

[Commander Kinsey]

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....

 

[Commander Kinsey]

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....

 

[Commander Kinsey]

On Thu, 02 Jul 2020 15:41:19 +0100, Ralph Mowery <rmowery28146@earthlink.net> 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.

Yes I\'ve heard of them, they\'re a measurement scale for pansies.

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 .

Safety movies designed to sell Fluke meters, and you fell for them hook line and sinker.

 

[Commander Kinsey]

On Thu, 02 Jul 2020 15:41:19 +0100, Ralph Mowery <rmowery28146@earthlink.net> 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.

Yes I\'ve heard of them, they\'re a measurement scale for pansies.

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 .

Safety movies designed to sell Fluke meters, and you fell for them hook line and sinker.

 

[Ralph Mowery]

In article <op.0nuzmdi9wdg98l@glass>, CFKinsey@military.org.jp says...

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.

Whyever not? Even the cheap ones usually state you can use them up to 1000 volts. I\'ve used them on 240 and 415 just fine. I used one on 2000 volts once, and it just failed inside, not even smoke or noise.

Because I have seen what damage can be done with those circuits.

I have also seen some safty films that the Fluke meter company put out.
Say you take your HF meter and by mistake have it on the ohms or amp
range. Normally an internal fuse would blow. However there is enough
power in the circuits to arc over the fuse, the meter leads instantly
almost explode or look like an arc welder. If you have one hand on each
lead it is possiable the insulation will melt off and maybe into your
hands. You could also become part of the circuit and fry.

Look here around the 6 minuit point.

https://www.youtube.com/watch?v=OEoazQ1zuUM

 

[Michael Terrell]

208 is a standard three phase voltage. It is three 120 volt lines phased 120 degrees apart.

 

[Ralph Mowery]

In article <op.0nuzmdi9wdg98l@glass>, CFKinsey@military.org.jp says...

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.

Whyever not? Even the cheap ones usually state you can use them up to 1000 volts. I\'ve used them on 240 and 415 just fine. I used one on 2000 volts once, and it just failed inside, not even smoke or noise.

Because I have seen what damage can be done with those circuits.

I have also seen some safty films that the Fluke meter company put out.
Say you take your HF meter and by mistake have it on the ohms or amp
range. Normally an internal fuse would blow. However there is enough
power in the circuits to arc over the fuse, the meter leads instantly
almost explode or look like an arc welder. If you have one hand on each
lead it is possiable the insulation will melt off and maybe into your
hands. You could also become part of the circuit and fry.

Look here around the 6 minuit point.

https://www.youtube.com/watch?v=OEoazQ1zuUM

 

[Ralph Mowery]

In article <op.0nu3kdf9wdg98l@glass>, CFKinsey@military.org.jp says...

Safety movies designed to sell Fluke meters, and you fell for them hook line and sinker.

No, I have actually seen a few blowups and the results of some others.

Have you ever worked at a place that has lots of 480 volt 3 phase
equipment ? I did before retiring. One learns to respect what can
hapen.

 

[Ralph Mowery]

In article <op.0nu3kdf9wdg98l@glass>, CFKinsey@military.org.jp says...

Safety movies designed to sell Fluke meters, and you fell for them hook line and sinker.

No, I have actually seen a few blowups and the results of some others.

Have you ever worked at a place that has lots of 480 volt 3 phase
equipment ? I did before retiring. One learns to respect what can
hapen.

 

[Ralph Mowery]

In article <op.0nu3kdf9wdg98l@glass>, CFKinsey@military.org.jp says...

Safety movies designed to sell Fluke meters, and you fell for them hook line and sinker.

No, I have actually seen a few blowups and the results of some others.

Have you ever worked at a place that has lots of 480 volt 3 phase
equipment ? I did before retiring. One learns to respect what can
hapen.

 

[Michael Terrell]

He is just an arc flash away from making an ash of himself.