Floating the 'scope

 

Why do they make 'scope inputs ground referenced to the third wire of
the AC plug?  Today I smoked the 10 ohm resistor that was separating
The AC ground from the 'ground' of my circuit.  I'd forgotten to float
the 'scope and connected -15V to the ground clip of the scope probe.

George H.

 


"George Hairoil"



** For obvious safety reasons.

It helps reduce the number of technicians getting electrocuted.

But  YOU go right ahead and float yours  - by all means.




....  Phil

 


Hi Phil,  now don't yell at me too much, it's Friday night here and
I'm half in the bag.

I've been floating 'scopes for.... say since the early '80's.  I
haven't been biten by it yet.  (Though I've made plenty of other
mistakes.)  What are the obvious safety reasons?

In today's mistake I was looking at the voltage from a heater
circuit.  The heater runs off +15 and -15 but knows 'nothing' about
ground.  (Well nothing except for the bypass caps, but no DC
connection.) Things weren't quite working right and I worried about
some oscillation.  I hooked up the 'scope to look.... opps.

George H.

(who believes that you make progress only as fast as you can make
mistakes...)

 

 "George Hairoil"


I've been floating 'scopes for.... say since the early '80's.  I
haven't been biten by it yet.  (Though I've made plenty of other
mistakes.)  What are the obvious safety reasons?


** My god you are stupid.



....  Phil

 

On 6/03/2010 2:49 PM, Phil Allison wrote:


 Welcome to an entirely new class of stupid, Phil.

 At a place I used to work at, the cro on my bench was floated by the
previous "tech", he just forgot to tell anyone about it.  And forgot to
label it too.  No clues at all unless you measured it, or took it apart
to actually look.

 Made worse by the fact it was a dual trace cro, and could have done the
job without floating it.

 I can only presume these idiots have been doing for so long, they stop
caring about the fact you hadn't had to do it since two trace (or more)
CROs appeared on the market.
 Hey, I don't care if they want to kill themselves, but their idiocy
will continue to kill others well into the future.

 I'm starting to think that being dropped as a baby isn't enough to
explain this level of stupid.