Modifications to equipment earthing arrangements.

[turretslug]

There have been a few previous threads on this and similar subjects and often there's been a bit of "doom-and-gloom" about them- "oh dear, daren't do anything, the full weight of inflexible law is just poised to fall like an anvil" etc.- but this quite long-running thread is actually more reassuring. I tend to follow Argus25 (and others') reasoning in that making really sure that something that was intended to be earthed is well and truly so after overhaul, and feel no shame in the generous use of modern things like heatshrink sleeving over primary-side connections and added low-current fusing.

One issue that I have with the "touch nothing, change nothing" argument is that quite often on the forum measures such as re-stuffing capacitors and other painstaking restoration measures are discussed in the general overhaul of a set- could one find oneself in court under cross-examination, "You appear to have taken considerable time and effort over exacting attention to cosmetics, and consider yourself to be informed and responsible in the field of electricity and electronic repair- and yet you made no effort to improve upon the evident safety shortcomings of something designed and built back in the 1930s"? I realise that there's an element of the "if you changed nothing, then it's not your fault" as discussed- but surely there's also a recognition of shortcoming responsibility? I would far rather the small risk of being professionally questioned about what I had changed or renewed in order to achieve what I felt was acceptable safety than say (a real example) leave a 70-year old metal-cased communications receiver (complete with tempting bare metal handles!) with its original 2-core rubber mains lead to potentially cause harm to unsuspecting third parties.

[Argus25]

To see something really amusing about electrical safety, scroll to the very last page of this article, it still makes me smile every time I read it:

http://worldphaco.com/uploads/THE_ME...DREA_KTE-5.pdf

The TV's manufacturers recommend that to be sure to electrocute yourself, you would stand in a bath and play with the electric light fixtures.

I doubt though it would be easy to sell TV kits these days that used such high voltages and fairly low internal Z supplies, but it is interesting there are Jacobs Ladder kits & Tesla Coil kits that might possibly, in some cases, deliver more than 10 to 30mA from their high voltage terminals while still holding the output voltage up over a few hundred volts.

Many years ago my brother built a high voltage supply into a chocolate box with a reed switch and magnet. The two electrodes were one long and short side of the box with aluminium foils. The HV generator was a small valve output transformer in reverse with a 9V battery driving it via an oscillator made from an AC127 & 128. The thing probably barely could supply a few mA.....so it should be safe. Then he had a photo of a semi-clad lady on the top, with the words "more inside" written on the box.

Of course most men rushed to open it up and got zapped lifting the lid. He left this thing on the desk of his Math professor at Uni, who also rushed to open it, but unfortunately, unknown to my brother, this fellow had some sort of cardiac issue and probably the fright of it set off an irregular beat. So he was carted off to the A&E and was fine later, but he refused to let my brother back into the math class again.

[The Philpott]

Scaling down from Tesla Coil/Jacob's Ladder kits, there are the little potted black boxes very much freely available that can spew 12 or 15kV pulses at low current with ease- from a 3v source. All very portable, yet still allowed under the classification of scientific toy, all the more so since it is effectively a component, not the finished article. (The finished article, if hand-held, being illegal in the UK, potentially even before you leave the house with it.)

Dave

[John10b]

That last part made me smile also Argus25. Let’s hope we still have common sense!
Cheers
John

[Argus25]

I saw a movie tonight that summarized the sentiment of this entire thread and it reminded me of a quote from a famous hair dresser:

The movie was "The Finest Hours" about a group of coast guard men who went out to save others from a ship called the Pendleton which had broken in half. It was a treacherous trip and when they got there the "rules" said the boat they were on was only "rated" for 12 persons, but there were 32 people to save. So they stuck 32 on the boat and all were saved.

The rules are great for the young and inexperienced, to keep them on the right track, but the experienced world famous Hair Dresser, Vidal Sassoon, knew better, he once said: "First you know the rules, then you can break them".

It certainly is better to know them first before doing it!

[Ed_Dinning]

Or the equally famous quote " Rules are for the guidance of wise men and the strict adherence of fools."

Ed