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From: Ron on 3 Jan 2010 11:20
On 03/01/2010 15:51, sparky wrote:
> On Jan 3, 10:48 am, Meat Plow<m...(a)petitmorte.net> wrote:
>> On Sun, 3 Jan 2010 15:13:01 +1100, "Phil Allison"
>> <phi...(a)tpg.com.au>wrote:
>>
>>
>>
>>
>>
>>
>>
>>> "David"
>>
>>> " Some pommy retard"
>>
>>>>> However, I can't think of any case where the use of an isolation
>>>>> transformer *increases* any hazard.
>>
>>>> Well, I sure can. When they listen to someones advice that it is OK to
>>>> touch either side of the output of the xformer. As Phil pointed out if
>>>> there is a problem that could be lethal
>>
>>> ** Aside from the above issue - the number one reason for NOT using an
>>> isolation tranny as the usual supply of AC power on a workbench is that the
>>> very same tech who has become oblivious to the danger of contacting live AC
>>> wiring WILL at some future time and place find themselves working on
>>> energised items WITHOUT the benefit of such isolation.
>>
>>> The DANGER is in the false impression of harmlessness that builds up in the
>>> mind of the tech.
>>
>>> Old habits die hard - but electricity kills quick.
>>
>> Becomeing complacent in or unconcerned with electrical hazards is a
>> fact of life (or death.) You're not going to save the world.- Hide quoted text -
>>
>> - Show quoted text -
>
>
>
> Anyone using an isolation transformer should not become complacent.
> It is a tool with hazards.
> Just the same as using a power saw has hazards, but the hazards can be
> minimized and the user must be vigilant.

An isolation transformer reduces the hazards, no one said it removes
them completely. It should be understood that anyone working on live
electrical equipment has the capacity to comprehend the dangers or is
otherwise advised to entrust the work to someone more competent.

To paraphrase Monty Python . "This thread is getting silly"


From: John Robertson on 3 Jan 2010 15:54
Dave Plowman (News) wrote:
> In article <postings-27DDC5.17183701012010(a)news.bigpond.com>,
> David <postings(a)REMOVE-TO-REPLYconfidential-counselling.com> wrote:
>>> No it hasn't. Isolation transformers are still used for many safety
>>> related reasons. But don't expect you to understand why. Obviously.
>
>> I am one of those who rarely agree with Phil, but this time he is giving
>> you the right info.
>
>> From your post Dave it does seem you do not understand the reasons
>> behind the use of isolation xformers when working on or testing gear.
>
> Seems to me some expect the use of an isolation transformer to be some
> form of magic bullet that removes all risks. It doesn't. But can reduce
> the sort of risk caused by one side of a mains supply being grounded. If
> you then ground one leg of the output of that transformer by any means you
> are back to square one.
> However, I can't think of any case where the use of an isolation
> transformer *increases* any hazard.
>

How about the technician who assumes that the isolation transformer has
decreased the risk of shock and behaves accordingly...without verifying
mains isolation before reaching inside live equipment?

Assumptions can be quite shocking!

John :-#)#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
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"Old pinballers never die, they just flip out."
From: Phil Allison on 3 Jan 2010 16:52

"Meathead Plonker"


> Becomeing complacent in or unconcerned with electrical hazards is a
> fact of life (or death.)


** Absolute BOLLOCKS it is.



..... Phil


From: GregS on 4 Jan 2010 10:14
In article <wIn%m.696$XU.576(a)newsfe03.iad>, "Leonard Caillouet" <nospam(a)noway.com> wrote:
>Please see page 2.
>
>http://www.cbtricks.com/miscellaneous/tech_publications/scope/floating.pdf

I swear I have seen documented procedures lifting the ground of an oscilloscope.
I though it was Tektronix, but I don't remember the details.

I like using battery scopes and also differential probes.

greg
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