Not a stage collapse but very bad

Re: Not a stage collapse but very bad

This has been discussed on other forums, while no precise explanation has been made public (most reports blame the microphone), the singer was also playing guitar so the shock path was most likely between guitar and mic. Generally both of those are supposed to be at ground potential. It is far more common for a faulty guitar amp to be the bad actor energizing the musician who gets grounded through the microphone. While less frequent, it is remotely possible that the mixer ground was hot, and the guitar provided the solid ground, while that is low probability.

I am an advocate of back line being powered through GFCI outlet strips, which would protect against the bad guitar amp. Hot ground on the mixer is harder to anticipate and protect against. While guitars can be AC grounded through a capacitor that could limit the current from such a shock path (in either direction) to less than lethal levels, few guitarists like the idea of modifying their guitars, even if it could save their life.

JR
 
Re: Not a stage collapse but very bad

A death whether from a collapsed stage or electrocution is still a needless death.

"Officials are investigating what went wrong, but initial reports cited faulty wiring on his microphone as the cause of the electric shock."
And another example of poor reporting.
A miswired mic does not have the potential to kill.
Figure either a fault in the PA console where the chassis became hot (which would have affected all mics) and would still need a path to ground,
or
As Mr. Briolini not only was the lead singer, he also played electric guitar.
So the more likely scenario was some type of amp faullt (hot chassis?, cut off ground pin? etc.) where full power was on the strings, and when he grabbed the mic, he completed the circuit to ground.
Mics generally connect the shield to the mic body.
The other possibility was a faulty outlet - RPBG - reverse polarity bootleg ground which would have made the chassis hot (through the amp ground), feeding hot through the cable shield to the guitar strings... Holding the hot guitar and grabbing the grounded mic -

The mic is always the fall guy for other faults that kill.

A GFCI on the backline stringer would have prevented this tragedy.
Testing guitar/mic with NCVT would have revealed the fault.
Bumping strings (don't hold any metal of the guitar) to the mic stand/microphone and see if sparks
(not recommended, but better than grabbing either guitar or mic) Brush strings and brush knuckles or back of hand to stand - if hot, the muscles in your hand will contract - basically releasing you from the danger.
Brushing the inside of your hand (or grabbing) will also cause muscle contraction, but the contraction will cause the hand to close with the inability to let go. With the guitar in one hand and the mic in the other, the inability to let go will put many times more current across your chest which will kill you.

A long, and better discussion of the problem, cause, and preventative measures at this link:
http://forums.prosoundweb.com/index.php/topic,152464.0.html

frank
 
Last edited:
Re: Not a stage collapse but very bad

One of the problem is peoples lack of understanding what a GFI does and why it's important to pay attention to ground faults.I have seen cases where some customers call and say somethings wrong with the GFI because I plugged the: refridgerator,sump pump,mixer rack, take your pick into a non GFI recepticle and it works.Yeah it works,but there's still a problem with the piece of equipment. Get it fixed!
 
Re: Not a stage collapse but very bad

frank kayser said:
A death whether from a collapsed stage or electrocution is still a needless death.


The mic is always the fall guy for other faults that kill.

A GFCI on the backline stringer would have prevented this tragedy.
Testing guitar/mic with NCVT would have revealed the fault.
Bumping strings (don't hold any metal of the guitar) to the mic stand/microphone and see if sparks
(not recommended, but better than grabbing either guitar or mic) Brush strings and brush knuckles or back of hand to stand - if hot, the muscles in your hand will contract - basically releasing you from the danger.
Brushing the inside of your hand (or grabbing) will also cause muscle contraction, but the contraction will cause the hand to close with the inability to let go. With the guitar in one hand and the mic in the other, the inability to let go will put many times more current across your chest which will kill you.

A long, and better discussion of the problem, cause, and preventative measures at this link:
http://forums.prosoundweb.com/index.php/topic,152464.0.html

frank
Click to expand...
Just to be clear, and I strongly advocate using GFCI on back line BUT... IF the fault was a hot ground on the mixer/console, a GFCI protected guitar amp would be ineffective at preventing the shock hazard. In that case the guitar would provide the innocent safety ground that completed the electrical path to kill him.

JR
 
Re: Not a stage collapse but very bad

John Roberts said:
Just to be clear, and I strongly advocate using GFCI on back line BUT... IF the fault was a hot ground on the mixer/console, a GFCI protected guitar amp would be ineffective at preventing the shock hazard. In that case the guitar would provide the innocent safety ground that completed the electrical path to kill him.

JR
Click to expand...

Of course you're absolutely correct. A GFCI on console would solve that. JR - would GFCI on FOH racks and/or amp racks be of any consequence to the performers on stage? Is there any situation where a GFCI would not be desirable from a safety standpoint (assuming the GFCI does not false trip)
 
Re: Not a stage collapse but very bad

frank kayser said:
Of course you're absolutely correct. A GFCI on console would solve that. JR - would GFCI on FOH racks and/or amp racks be of any consequence to the performers on stage? Is there any situation where a GFCI would not be desirable from a safety standpoint (assuming the GFCI does not false trip)
Click to expand...
Apart from the scenario JR mentioned where the current comes from another non protected source I can't think of one, now "false" tripping is a problem as people will pull the GFI from the system and blame it, I would argue that a correctly wired and good quality GFI/RCD isn't false tripping but warning you of a possible fault.
I've only had one really annoying day with trips for no apparent reason, when actually the problem was someone had plugged into a different feed with a different earth and the small voltage difference caused some random trips, we discovered this on the 2nd day of a 3 day event. Now if for some reason voltage had got onto that other earth path then there would have been a real issue, we were all blaming the hall's breakers when actually it was a guitarist who couldn't wait for power to be ran to him and had plugged into a handy wall socket he found nearby. Lesson learned and I'm even fussier now about where people plug in.G
 
Top Bottom