While I tend to agree that the shock hazard (in and of itself) is negligible to healthy individuals, the real danger, IMO, owes to (corollary) involuntary motion with attendant liability to dropping, or otherwise disrupting, the tube...

Best Regards
HP

In the aproximate vicinity of 15kHz, 25kV can draw a continuous hot arc. And you don't even need that much voltage - back in the days of valve/transistor hybrids, I was trying to adjust a dodgy horizontal oscillator while peering over the top at a set that was working. The first thing I became aware of was the smell of burning flesh, my knuckle was too close to a PCB track and drew a HF arc.

That type of electrical burn takes a long time to heal!

 

In the aproximate vicinity of 15kHz, 25kV can draw a continuous hot arc. And you don't even need that much voltage - back in the days of valve/transistor hybrids, I was trying to adjust a dodgy horizontal oscillator while peering over the top at a set that was working. The first thing I became aware of was the smell of burning flesh, my knuckle was too close to a PCB track and drew a HF arc.

That type of electrical burn takes a long time to heal!

Indeed! 'RF' burns (AF burns?) tend to be deep! --- I know I've taken 'my share' off (antediluvian) metal envelope CRTs -- 'poly' jackets notwithstanding!

Best regards
HP

 

Indeed! 'RF' burns (AF burns?) tend to be deep! --- I know I've taken 'my share' off (antediluvian) metal envelope CRTs -- 'poly' jackets notwithstanding!

Best regards
HP

AFAIK: it cooks/kills the surrounding tissue, so very restricted blood flow to the wound area.

 

and a lot of injuries were due to the invoulentary muscle contractions from the high voltage, cuts and such. once threw a screwdriver across the shop and stuck it in the wall from a discharge.

 

and a lot of injuries were due to the invoulentary muscle contractions from the high voltage, cuts and such. once threw a screwdriver across the shop and stuck it in the wall from a discharge.

As I stated in a previous post, I didn't know about it until I smelled burning flesh.

At 15kHz, it can be drawing an arc to your hand and you don't feel a thing.

 

As I stated in a previous post, I didn't know about it until I smelled burning flesh.

At 15kHz, it can be drawing an arc to your hand and you don't feel a thing.

Very true! --- FWIW I think alfacliff was referring to a DC shock from energy (electrostatically) 'stored' in the CRT's capacitance --- Which, again, can be especially nasty if it results in breakage of the CRT!

Best regards
HP

 

I have had my share of CRT HV zaps and agree, not pleasant, but in the case of a non-powered CRT it is more of a unpleasant experience than a real danger, I always thought there was a little too much hyperbole on this and this sort of confirms it.
http://lowendmac.com/2007/the-truth-about-crts-and-shock-danger/
Max.

Excellent read! Thanks for sharing. Sort of puts things in a more proper perspective despite the fact that simple common sense will usually see a person thorough even a bit of discomfort. I fear however that common sense is not as abundant as it once was or seemed to be which is why I keep a certain book around despite the fact that it is a Paine!

 

Very true! --- FWIW I think alfacliff was referring to a DC shock from energy (electrostatically) 'stored' in the CRT's capacitance --- Which, again, can be especially nasty if it results in breakage of the CRT!

Best regards
HP

When I was in the trade, I kept a test lead from an old meter that got scrapped, for discharging the CRT.

The pointy end was a good shape for slipping under the rubber cap and the meter end had a 4mm banana plug, that nicely fit the strain relief collar on a crocodile clip - but I soldered it as well as I didn't want it falling out unnoticed.

Its dead important to only discharge it to the wire braid that grounds the outside coating on the CRT!

Apparently the glass dielectric has a polarising effect or something, a CRT that's been discharged can recover after a few minutes with enough charge to still zap you. Usually I'd leave the shorting probe in place while I worked on the chassis.

Back then I smoked, so if the probe hadn't been there long, I'd roll a cigarette to kill some time before putting my hand in there.

 

Apparently the glass dielectric has a polarising effect or something, a CRT that's been discharged can recover after a few minutes with enough charge to still zap you.

Aye! 'Tis the Imp of Dielectric Absorption come a'calling!

Best regards
HP