oscilloscope without wire ground

Tobias Gadelha · 2013-07-28T18:49:54+00:00

Is there any risk to use oscilloscope without wire ground? Because with wire ground there is a short circuit when I use GND on the line.

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Tom Biasi 13 years ago

Daniel, Scopes have the outer shield connector attached to the BNC conector. The outer connector of the BNC is common with the chassis of the scope. So the alligator clip on the scope is the same as chassis ground on the scope. In the USA one of the line wires is hot and the other is neutral. In most cases the neutral and ground are the same, but not always. In some

220 volt countries both L1 and L2 are hot to ground. It would serve you to consider the clip on the scope a chassis and earth ground. Anywhere you touch it is like touching ground there.

Tom

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Tom Biasi 13 years ago

Neutral and ground are not always the same.

Thank you. I try.

Agreed.

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Phil Allison 13 years ago

** Of course they are not the SAME !!!!!!!

Neutrals ARE current carrying conductors.

Safety grounds are NOT, until a fault condition arises.

Make your point clear.

... Phil

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Tobias Gadelha 13 years ago

Em terça-feira, 30 de julho de 2013 02h01min58s UTC-3, Phil Allison escr eveu:

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a

Phil

I'm from Brazil and here N= Neutral ; L1 =220V (-120º); L2=220V (0 º) and L3(+120º) therefore L1 in oscilloscope will be GND and L2 the pr ove. Is it possible with the wire groud conected in the jack.

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Tobias Gadelha 13 years ago

Em terça-feira, 30 de julho de 2013 02h01min58s UTC-3, Phil Allison escr eveu:

box

a

Phil

I'm from Brazil and here N= Neutral ; L1 =220V (-120º); L2=220V (0 º) and L3(+120º) therefore L1 in oscilloscope will be GND and L2 the pr ove. Is it possible with the wire groud conected in the jack?

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Michael A. Terrell 13 years ago

His IP address resolves to Brazil.

Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.

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Phil Allison 13 years ago

"Tobias Gadelha"

I'm from Brazil and here N= Neutral ; L1 =220V (-120º); L2=220V (0º) and L3(+120º) therefore L1 in oscilloscope will be GND and L2 the prove.

** My god, the fool IS mucking about with 3 phase power !

Is it possible with the wire groud conected in the jack.

** Question time:

Have you got a dual trace /channel scope with "invert" function on one channel ?

Do you have two 10:1 probes ?

If so, others have given you the answer already.

BTW:

3 phase power is VERY DANGEROUS !!!

Beginners should NOT be touching it.

... Phil

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Tom Biasi 13 years ago

I made my point clear Phil.

You said, "Neutral conductors are always linked to ground at the service box."

I said," In the USA neutral and ground are "usually" connected at the service box but not always."

That's clear enough. No need to go beyond that.

Tom

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Phil Allison 13 years ago

** Clear as mud - pal.

** NO it is NOT !!!!!!!!!

** It must be connected to ground somewhere - or else it is simply NOT a neutral.

Ever see the movie "Groundhog Day" ??

... Phil

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Ian Field 13 years ago

Persuade him to set up a live feed webcam while I go get deckchair & popcorn.

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Ian Field 13 years ago

IWHT in that case L1 & L2 mean "line 1" & "line 2" - not live.

If "L" refers to live - there's probably a 3rd one lurking somwhere!

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Ian Field 13 years ago

I used to do it a lot in the 80's when most TVs had bridge-rectifier mains in, and chassis pulsing at -320V.

In some the 'SMPSU' was as basic as a SCR masquerading as a buck regulator - they used a bridge-rectifier input (with its live chassis) to get 100Hz pulses so they could use a smaller inductor.

Can't deny it bit me a few times!

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