Variac question

aling with before employing an isolation transformer. I read the article. IMO, the article title is an attention getting and his point is that the is olation transformer presents a 'false sense of safety'. The assumption tha t most ppl will make is that one blindly needs to install an isolation xfor mer in all applications and it will keep you safe. There are limitations b ased on the circuits one is dealing with.

To remain safe when working on live equipment one needs to understand what one is dealing with whatever safety systems are in use. Isos have their lim itations of course, so do all safety methods.

kage detector" is a general statement but also a bit misleading. RCDs are N OT recommended and ELCBs are essential.

Woah. Voltage operated ELCBs are obsolete, a known hazard and offer no prot ection whatever against shock when working on a live chassis appliance. The y only protect against the earth system becoming live as a result of a high current fault (not via a human) that would otherwise raise the earth syste m above 50v. That's all they do. They were obsolete in the 1980s. Current o perated ELCBs _are_ RCDs.

-elcab-engineers

It's yet another article with both correct points and some confusion.

rrect.

through 2000. I grew up in the shop and serviced TVs and other electronic gear from the 60, 70, and 80s. I can attest that the live chassis was not only in the 90's. I've seen it in the 70s and 80's TVs. I've also seen it in electronic gear in the 2010s - e.g. soldering stations/hot air rework s tations from China, as well as three voltage power supplies from China.

Unless I'm mistaken I don't think anyone said live chassis kit only existed from the 90s. I have had live chassis stuff from post-2000, 90s, 80s, 70s, 60s, 50s, 40s, 30s, 20s and one item that might have been from the 10s or

20s. By the time you go that far back 'live chassis' becomes somewhat meani ngless in that it was normal to have live bits all hanging out.

e working on and dont blindly apply 'safety measures'...that doesn't mean t o ignore them. It means to apply them but know what areas of 'safety' they are meant to protect.

that of course is vital when working on live equipment. Anyone that does so without understanding what they're doing or gets careless is in trouble. I n about of 99.2% of those cases a shock awakes them to the need to be sensi ble. Mortality is somewhere roughly in the region of 1 per 600 shocks.

There is NO safety system that can protect people against that. RCDs offer zero protection against shock from transformer derived B+, don't protect ag ainst L-N shocks and don't always work on L-E shocks. ELCBs offer no shock protection at all from live working hazards. Isos offer limited protection. Never touching the equipment with both hands offers limited protection. An earth-free workzone offers limited protection, etc etc. Sometimes you just need to know what you're doing or not do it.

NT

Reply to
tabbypurr
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aling with before employing an isolation transformer.

** Which practically counts out the servicing equipment with unknown faults .
** Good for you. IMO, the article title is an attention getting and his point is that the is olation transformer presents a 'false sense of safety'. The assumption tha t most ppl will make is that one blindly needs to install an isolation xfor mer in all applications and it will keep you safe. There are limitations b ased on the circuits one is dealing with.

kage detector" is a general statement but also a bit misleading. RCDs are N OT recommended and ELCBs are essential.

** The use of RCDs is highly recommended in the article *YOU* cited !!!!

QUOTE:

" RCDs are an extremely effective form of shock protection " ------------------------------------------------------------

-elcab-engineers

** Good - cos no-one here actually said that.

Do you have a reading disability ??

Never mind, NG postings are notorious for being confusing & difficult to f ollow.

.... Phil

Reply to
Phil Allison

One error is where he writes, "Without isolation, you know exactly what is dangerous at all times. It's quite apparent that you can't touch anything that's at mains potential,"

That's poor English. Obviously you can touch anything that's at mains potential but you shouldn't.

Reply to
Lucifer

one of too many errors in that article.

NT

Reply to
tabbypurr

** The English grammar is fine and there is no technical error.

** Wot pedantic twaddle, the word "safely" in front of the word "touch" is understood from general context.

.... Phil

Reply to
Phil Allison

There are times when I am told: But, you know what I mean!

To which the only valid answer is: No, I know what you said (wrote). I am still trying to discern what you mean.

Be very, very careful about making assumptions in a technical discussion, and in using any of poor grammar, syntax, word-choice, punctuation or spelling. The consequences may be significant - and surprising.

Peter Wieck Melrose Park, PA

Reply to
peter wieck

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