Mains measurement with PicoScope 5000

[Damascus]

I am in the market for a scope that I can use for a number of purposes, from serial bus to VFD output.  I am looking at thePicoScope 5244D, but the manual mentions that it is not for mains use.

But shouldn't a quality CAT II 1:100 probe be able deal with this issue, measuring nothing more than 600Vac.  Am I missing something here?

[2N3055]

I am in the market for a scope that I can use for a number of purposes, from serial bus to VFD output.  I am looking at thePicoScope 5244D, but the manual mentions that it is not for mains use.

But shouldn't a quality CAT II 1:100 probe be able deal with this issue, measuring nothing more than 600Vac.  Am I missing something here?

Yes, you are missing at least two dozen discussions on that topic on this very forum.
Search for it...
google "site:eevblog.com measuring mains with scope"

[rvalente]

For messing with a VFD and other high energy stuff please, get yourself an isolated scope or, at least, a differential probe.
Because it is safer and you'll need to probe with different grounds.

Although, if you're really looking forward with PICO I would additionally to the the differential probe get a USB isolator, its a must.
Checking briefly the PICO I've seen its non isolated usb 3.0 so I believe the isolator would not be cheaper and easy to find

Do you need the set of fetures from the pico? For VFDs I would get a used hand held scope (because they are the cheapest channel isolated, I've myself a THS720A, its pretty old, slow and very very low memory depth, but its isolated and CAT rated).

I would suggest looking for a used U1610A or U16xx series, Siglent also have a isolated channels and are cheaper than the THS3000
Ooohh, the TPS2000 is also channel isolated as long as I remember, low density memory but, safe.

[Damascus]

I can isolate a PICO, just run the pc on battery.

I want the serial decoding features not available with handheld.

[Damascus]

I am in the market for a scope that I can use for a number of purposes, from serial bus to VFD output.  I am looking at thePicoScope 5244D, but the manual mentions that it is not for mains use.

But shouldn't a quality CAT II 1:100 probe be able deal with this issue, measuring nothing more than 600Vac.  Am I missing something here?

Yes, you are missing at least two dozen discussions on that topic on this very forum.
Search for it...
google "site:eevblog.com measuring mains with scope"

Funny, I didn't see one about the note in the Pico manual.

[rvalente]

I can isolate a PICO, just run the pc on battery.

I want the serial decoding features not available with handheld.

I believe this would be very limiting and prone to error but, its a way.

Just out of curiosity, why are you willing to pay 2K USD on the pico?
Is it because of the vertical resolution (is it true resolution or over sampling?)

[Damascus]

Portability, 200MHz, serial decoding in software (manchester)

[rvalente]

Great!

So have your doubt been resolved?

[engrguy42]

I agree. No need to waste time searching the forum. Simple answer:

Get a differential probe.

They have meghoms of input resistance, and generally also an optoisolator to isolate the USB.

Disconnecting case grounds is a bad idea.

[Damascus]

Disconnecting case grounds is a bad idea.

This is my issue. Why?  I've used a handheld 199C on mains before, without differential probes, and no case ground to disconnect if I wanted to.

What's the difference between floating a Pico and using a handheld that Pico would make a statement 'not for mains'.

[engrguy42]

I'm not familiar with a Pico, but if it has a metal case with an earthing prong connected to the mains then that earthing is there for your protection.

If it has a plastic case with no accessible metal, and no 3-prong mains connection and no USB to earth connection, then maybe you don't need it. For example, if it's handheld like a plastic multimeter, and powered by battery, for example, then yeah, you probably don't need a differential probe.

But I'm assuming since the mfr said don't use it on mains they have a reason. 

[Damascus]

From what I see, it has rubber standoffs, powered by USB(2 chan), and a seprate ground tab.  Almost as if it is designed to be floated.

[rvalente]

But I'm assuming since the mfr said don't use it on mains they have a reason. 

Probably the equipment was not tested/rated for CAT because there is a low degree or no protection at all

IMHO: Anyway, I've never been a fan of instruments without screens and buttons. If its for field use the last thing I want is another brick attached and dependeble of my computer. You can't easily bring a PC + device to a cabinet to troubleshoot a VFD and this equipment is not adequate for field service.
Anyway with 2 grand as budget I would get anything but a pico scope, maybe If i needed the 16 bit precision, but for what?

[engrguy42]

From what I see, it has rubber standoffs, powered by USB(2 chan), and a seprate ground tab.  Almost as if it is designed to be floated.

Try emailing the mfr and see if they agree with you. 

[Damascus]

But I'm assuming since the mfr said don't use it on mains they have a reason. 

Probably the equipment was not tested/rated for CAT because there is a low degree or no protection at all

IMHO: Anyway, I've never been a fan of instruments without screens and buttons. If its for field use the last thing I want is another brick attached and dependeble of my computer. You can't easily bring a PC + device to a cabinet to troubleshoot a VFD and this equipment is not adequate for field service.
Anyway with 2 grand as budget I would get anything but a pico scope, maybe If i needed the 16 bit precision, but for what?

In my business, all I do is bring a PC and test gear to cabinets inside and outside in all weather conditions - that's what it's for.  And that Pico fits in a computer bag real easy.  Show me something with 200MHz and Manchester code that you would buy.

[engrguy42]

Do you honestly expect people here to tell you "yeah, ignore the manufacturer's recommendations" and plug your probe into the mains?? Seriously?    All because your company doesn't want to spend $180 on a differential probe?



 

[Damascus]

No, I expected some intelligent and informed feedback by people experienced and knowledgeable in the field.

As opposed to answers from people with no experience or idea of the equipment they are talking about.  This is you.

This place is worse than stack overflow.  Adios.

[2N3055]

I am in the market for a scope that I can use for a number of purposes, from serial bus to VFD output.  I am looking at thePicoScope 5244D, but the manual mentions that it is not for mains use.

But shouldn't a quality CAT II 1:100 probe be able deal with this issue, measuring nothing more than 600Vac.  Am I missing something here?

Yes, you are missing at least two dozen discussions on that topic on this very forum.
Search for it...
google "site:eevblog.com measuring mains with scope"

Funny, I didn't see one about the note in the Pico manual.

That is why you have me.
Seriously, do the search. This is already long topic with no answers. It's done to death here, together with all the reasons, and which are good  probes etc.
I wrote about it many times, and won't repeat myself. Also many users here feel like that , and don't even want to write explanation why. It's tiresome repeating stuff all the time.

Also you seem to post here because you wanted us to confirm you're right with your opinion, not to have right answer. Don't float Picoscopes. You and Pico might survive it, but not every time, all the time. PC has exposed GND on all connectors, Pico has exposed GND on all BNCs. Most importantly, all BNC on Pico are connected together.
Best scope for that kind of work is one with isolated channels (from scope and each other)

Using High voltage diff probes makes all those problems go magically avay, on all scopes, all the time.
Pico is superb for that work, because of custom probes.
As far as Picoscopes, i love them, have two. They have many possibilities other scopes don't..
All the best,

[engrguy42]

First of all, "worse than Stackoverflow"

Wow. That's hitting WAY below the belt.

Secondly, a great philosopher once said, "People believe what they want to believe. Facts are irrelevant".

Let's just hope in this case it doesn't result in a foolish, unnecessary injury.

[rvalente]

Why sometimes people (usually with very low posting counts) come here to ask stuff as this is a consulting place, where answers must be given accordingly to what they want to read?

I can't get this nonsense... anyway, i'm off here.