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#1 2014-12-09 22:44:57

Bzean123
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Registered: 2014-05-09
Posts: 110
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2014-12-09 22:44:57

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#2 2014-12-11 00:49:26

ronws
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Registered: 2010-05-23
Posts: 11731
Reputation :   139 

Re: Singer Electrocuted by Mic

Funny how no one has commented. I have been shocked a number of times in my career as an electrician. Not from faulty mics. From touching wires that were energized. It didn't feel so good.


"When the daylight is rising up in my eyes ..." - Klaus Meine

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#3 2014-12-11 14:45:29

Bzean123
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Registered: 2014-05-09
Posts: 110
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Re: Singer Electrocuted by Mic

ronws wrote:

Funny how no one has commented. I have been shocked a number of times in my career as an electrician. Not from faulty mics. From touching wires that were energized. It didn't feel so good.

Yeah, 4 pages of guitarists discussing a vocalist's electrocution, but nothing from the vocalists. Oh well.

Ron, as an electrician maybe you can give us some tips on avoiding electrocution by mic/musical instrument.

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#4 2014-12-11 15:59:57

ronws
TMV Forum Member
Registered: 2010-05-23
Posts: 11731
Reputation :   139 

Re: Singer Electrocuted by Mic

Same thing I teach beginner helpers and students (when I was teaching in a trades program)- electricity seeks the shortest route to ground, stay out of its way.

Some time ago, a person here had a similar problem with her mic and where it was jacked into a mixing board in her studio.

The short may not be coming from the mic but from somewhere else in the system, searching for a way to get to ground and a human standing in the rain makes a perfectly good path for electricity.

Part of the problem is going to be the quality and availability of GFCI protection in whatever venue. And that can vary from country to country. Ground Fault Current Interruptor (GFCI) causes a circuit to open when something grounds out but not because of ground. There is a sensor loop in a GFCI breaker, switchgear, or outlet that sense changes of current level on the neutral wire. A change of .03 percent or greater causes it to trip.

Current going completely to ground, for example, would be a change of current level greater than .03 percent.

However, a tripped GFCI is not always a sign of shorted current. Some equipment and devices, like some of the mosquito misting machines use what is called a buck-n-boost transformer, also known as an autotransformer where the neutral is common to line and load side of the transformer. This causes two levels of current on the same neutral and the GFCI can trip, even though both the GFCI and the transformer are functioning normally.

Anyway, so, precaution is to make sure that your equipment is grounded and plugged into receptacles that are grounded with a distinctive ground wire that is not used for neutral or any normal current return. Neutral is for the current return.

If the building you are in is old, it may not have a separate ground. so, the next best option is to bring your own portable GFCI device. For example, Home Depot and other DIY stores sell extension cords and power strips with built-in GFCI protection and a re-set button. This is advisable and, in fact, in the NEC (National Electric Code book), an old house without ground wire can be made modernly code-compliant by replacing existing outlets with GFCI's. One word of caution, you don't want to load on GFCI on another GFCI, it will make the first one trip because the sensor loop is sending back current on the neutral. Trust me, I know this from actual experience, as well as theory.

Anyway, that's the long and short of it. If you don't know the state of GFCI protection in a venue or you DO know it has none, bring your own GFCI protection.

However, you need one rated for the amperage load you expect to have. And what is that?

Well, what is the power output? power is in watts. current = power / volts. Most guys' equipment is 120 V. My guitar amp is 200 watts rms (root mean square) and that's a good average number. 200 w / 120 v = 1.7 amps.

Also, remember that, at least in America, NEC expects that you should calculate circuit loads in this fashion.

100 % of non-continuous loads plus 125 % of continuous loads = total amps.
Continuous is defined as 3 hours or more of continuous operation. For example, many people will have lights on for more than three hours. If you do not know, then it is better to assume all loads on the circuit are continuous. So, you need a circuit that can handle 125% of your calculated load. This is to allow for power surges, motor starts. Motors start from a dead stop, called locked rotor current and require more current to start than to run.

The easier way is to work backwards. Take your available power, such as a 20 amp GFCI power strip and find 80 percent of that. 80 percent is the reciprocal of 125 %. 80 percent of 20 amp (standard 120 v circuit in America) is 16 amps. So, try not to put more than 16 amps no that strip but certainly no more than 20.

Also, you can test continuity in ground of your equip by using a tester set on ohms or a continuity setting. A tone or zero ohms means the wire is conducting. the check against other conductors in the cable. There should be no tone or a resistance of 2Mohm (Mega-ohm) to infinity, which means other wires are not in contact with ground.

Be aware that some equipment to operate properly is continuous between ground and neutral. In fact, test your equipment while it is completely disconnected.

This is because, in a building, what is called the ground fault current path is a requirement that allows the thermal mag-trip that most breakers are, to trip. Code requires that neutral and ground be bonded together once and only once at the first means of disconnect, which is a disconnect or switchgear for a building, a disconnect for a house, or the main electrical panel in the house with its main disconnect breaker (usually back to back with the meter base.)

This ground fault current path is so that a current going to ground will get on the ground wire and go all the way back to the first means of disconnect and jump on the neutral and go back to the supplying transformer (the power company transformer, in regards to houses) so that it comes back out on the hot and through the offending breaker at twice the current value, which causes it to heat up and the breaker has a heat-sensitive metal that causes the breaker to open or "trip." Without this, the breaker would stay on and something or someone would get flambe'd.

That's the short version. I could go into excruciating complete detail.

Electricity seeks the shortest route to ground, stay out of its way. I try to and I am usually successful but I used to get bit about once a year.

120 volts feels like a nerve tic, to me. 277 V (commercial lighting) and 480 V (commercial 3 phase power), now that hurts and will get my attention.

An exercise for those feeling lucky. In 3 phase power, you find current with the same formula but you have to account for 3 phases. I = VA/[1.732*E]. Current equals watts or volt-amps divided by the voltage times 1.732.

1.732 is the square root of 3. Can you explain why that is? I can but that would be showing off.

You also come at the same figure with spherical trig, which is how I initially studied. Hint, it is the cosine of an angle. Of course, I have an advantage, knowing how 3 phase power is created.
\m/


"When the daylight is rising up in my eyes ..." - Klaus Meine

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#5 2014-12-11 18:58:02

Bzean123
TMV Forum Member
Registered: 2014-05-09
Posts: 110
Reputation :   

Re: Singer Electrocuted by Mic

Thanks a million Ron! Later today I will sit down and read through this carefully.

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#6 2014-12-12 18:48:32

Adolph Namlik
Executive Director, The Modern Vocalist World
From: "No Name", New York
Registered: 2008-11-15
Posts: 748
Reputation :   17 

Re: Singer Electrocuted by Mic

ronws wrote:

Same thing I teach beginner helpers and students (when I was teaching in a trades program)- electricity seeks the shortest route to ground, stay out of its way.

Some time ago, a person here had a similar problem with her mic and where it was jacked into a mixing board in her studio.

The short may not be coming from the mic but from somewhere else in the system, searching for a way to get to ground and a human standing in the rain makes a perfectly good path for electricity.

Part of the problem is going to be the quality and availability of GFCI protection in whatever venue. And that can vary from country to country. Ground Fault Current Interruptor (GFCI) causes a circuit to open when something grounds out but not because of ground. There is a sensor loop in a GFCI breaker, switchgear, or outlet that sense changes of current level on the neutral wire. A change of .03 percent or greater causes it to trip.

Current going completely to ground, for example, would be a change of current level greater than .03 percent.

However, a tripped GFCI is not always a sign of shorted current. Some equipment and devices, like some of the mosquito misting machines use what is called a buck-n-boost transformer, also known as an autotransformer where the neutral is common to line and load side of the transformer. This causes two levels of current on the same neutral and the GFCI can trip, even though both the GFCI and the transformer are functioning normally.

Anyway, so, precaution is to make sure that your equipment is grounded and plugged into receptacles that are grounded with a distinctive ground wire that is not used for neutral or any normal current return. Neutral is for the current return.

If the building you are in is old, it may not have a separate ground. so, the next best option is to bring your own portable GFCI device. For example, Home Depot and other DIY stores sell extension cords and power strips with built-in GFCI protection and a re-set button. This is advisable and, in fact, in the NEC (National Electric Code book), an old house without ground wire can be made modernly code-compliant by replacing existing outlets with GFCI's. One word of caution, you don't want to load on GFCI on another GFCI, it will make the first one trip because the sensor loop is sending back current on the neutral. Trust me, I know this from actual experience, as well as theory.

Anyway, that's the long and short of it. If you don't know the state of GFCI protection in a venue or you DO know it has none, bring your own GFCI protection.

However, you need one rated for the amperage load you expect to have. And what is that?

Well, what is the power output? power is in watts. current = power / volts. Most guys' equipment is 120 V. My guitar amp is 200 watts rms (root mean square) and that's a good average number. 200 w / 120 v = 1.7 amps.

Also, remember that, at least in America, NEC expects that you should calculate circuit loads in this fashion.

100 % of non-continuous loads plus 125 % of continuous loads = total amps.
Continuous is defined as 3 hours or more of continuous operation. For example, many people will have lights on for more than three hours. If you do not know, then it is better to assume all loads on the circuit are continuous. So, you need a circuit that can handle 125% of your calculated load. This is to allow for power surges, motor starts. Motors start from a dead stop, called locked rotor current and require more current to start than to run.

The easier way is to work backwards. Take your available power, such as a 20 amp GFCI power strip and find 80 percent of that. 80 percent is the reciprocal of 125 %. 80 percent of 20 amp (standard 120 v circuit in America) is 16 amps. So, try not to put more than 16 amps no that strip but certainly no more than 20.

Also, you can test continuity in ground of your equip by using a tester set on ohms or a continuity setting. A tone or zero ohms means the wire is conducting. the check against other conductors in the cable. There should be no tone or a resistance of 2Mohm (Mega-ohm) to infinity, which means other wires are not in contact with ground.

Be aware that some equipment to operate properly is continuous between ground and neutral. In fact, test your equipment while it is completely disconnected.

This is because, in a building, what is called the ground fault current path is a requirement that allows the thermal mag-trip that most breakers are, to trip. Code requires that neutral and ground be bonded together once and only once at the first means of disconnect, which is a disconnect or switchgear for a building, a disconnect for a house, or the main electrical panel in the house with its main disconnect breaker (usually back to back with the meter base.)

This ground fault current path is so that a current going to ground will get on the ground wire and go all the way back to the first means of disconnect and jump on the neutral and go back to the supplying transformer (the power company transformer, in regards to houses) so that it comes back out on the hot and through the offending breaker at twice the current value, which causes it to heat up and the breaker has a heat-sensitive metal that causes the breaker to open or "trip." Without this, the breaker would stay on and something or someone would get flambe'd.

That's the short version. I could go into excruciating complete detail.

Electricity seeks the shortest route to ground, stay out of its way. I try to and I am usually successful but I used to get bit about once a year.

120 volts feels like a nerve tic, to me. 277 V (commercial lighting) and 480 V (commercial 3 phase power), now that hurts and will get my attention.

An exercise for those feeling lucky. In 3 phase power, you find current with the same formula but you have to account for 3 phases. I = VA/[1.732*E]. Current equals watts or volt-amps divided by the voltage times 1.732.

1.732 is the square root of 3. Can you explain why that is? I can but that would be showing off.

You also come at the same figure with spherical trig, which is how I initially studied. Hint, it is the cosine of an angle. Of course, I have an advantage, knowing how 3 phase power is created.
\m/

Excellent post, ronws !!!

I'm also a certified electrician and I think it's great that you shared this !!!


Adolph C. Namlik
Executive Director ~ The Modern Vocalist World
Western N.Y.
adolph@themodernvocalist.com
http://www.themodernvocalist.com/profile/AdolphNamlik
Email : chief188@hughes.net
716~257~9606
"My Life's A Stage"

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#7 2014-12-12 20:04:37

MDEW
TMV Forum Member
Registered: 2012-06-24
Posts: 2866
Reputation :   32 

Re: Singer Electrocuted by Mic

I couldn't follow any of that Ronws, but I was never good at math. :P I usually know I am in trouble when I start singing and my lips start to tingle.......Probably not the best way to look for short cicuits in your setup. :/
  Yes I have sang in the rain with the power cords just laying in mud.....I'm a hillbilly. :rolleyes:


"Knock me down, It's all in vain. I'll get right back on my feet again."  Pat Benatar

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#8 2014-12-13 01:40:25

ronws
TMV Forum Member
Registered: 2010-05-23
Posts: 11731
Reputation :   139 

Re: Singer Electrocuted by Mic

I've done scary stuff, too. Some years ago, the Denton County Courthouse added some more parking lot with some more pole lights. And there I was, standing in puddles in a driving rain with a crane to set the 25' poles and there was a lightning strike about a mile away that got my attention, as I was holding on to the pole to steady it onto the anchor bolts in the concrete pedestal.

As a way of thanks, the company I worked for while doing that later laid me off at the first sign of needing to lay people off.

Anyway, so,  I hope people gain benefit from words. I may be an okay singer. But I have also been studying electrical and electronic theory since 1975, doing electrical work since 1983. I have a master license. Of course, most days, that means nothing. I have been subjected to helpers with less than a year of experience trying to tell me how it's done. Old ladies disagreeing with me on how a mosquito misting machine will trip a GFCI in their yard. They just assume they know more than I do because they have more money.

Makes sense to me ...

Last edited by ronws (2014-12-13 01:40:58)


"When the daylight is rising up in my eyes ..." - Klaus Meine

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#9 2014-12-13 19:02:19

Adolph Namlik
Executive Director, The Modern Vocalist World
From: "No Name", New York
Registered: 2008-11-15
Posts: 748
Reputation :   17 

Re: Singer Electrocuted by Mic

ronws wrote:

I've done scary stuff, too. Some years ago, the Denton County Courthouse added some more parking lot with some more pole lights. And there I was, standing in puddles in a driving rain with a crane to set the 25' poles and there was a lightning strike about a mile away that got my attention, as I was holding on to the pole to steady it onto the anchor bolts in the concrete pedestal.

As a way of thanks, the company I worked for while doing that later laid me off at the first sign of needing to lay people off.

Anyway, so,  I hope people gain benefit from words. I may be an okay singer. But I have also been studying electrical and electronic theory since 1975, doing electrical work since 1983. I have a master license. Of course, most days, that means nothing. I have been subjected to helpers with less than a year of experience trying to tell me how it's done. Old ladies disagreeing with me on how a mosquito misting machine will trip a GFCI in their yard. They just assume they know more than I do because they have more money.

Makes sense to me ...

(See BOLD print) HA HA !!! Been there myself Ron when I was in the construction business :rolleyes:

See you (and ALL of our members), in our "NEW HOME" !!!!!!


Adolph C. Namlik
Executive Director ~ The Modern Vocalist World
Western N.Y.
adolph@themodernvocalist.com
http://www.themodernvocalist.com/profile/AdolphNamlik
Email : chief188@hughes.net
716~257~9606
"My Life's A Stage"

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#10 2014-12-13 19:10:33

Adolph Namlik
Executive Director, The Modern Vocalist World
From: "No Name", New York
Registered: 2008-11-15
Posts: 748
Reputation :   17 

Re: Singer Electrocuted by Mic

Robert, per your video : "Another six years" ???

How about MANY, MANY MORE ? :D :cool:


Adolph C. Namlik
Executive Director ~ The Modern Vocalist World
Western N.Y.
adolph@themodernvocalist.com
http://www.themodernvocalist.com/profile/AdolphNamlik
Email : chief188@hughes.net
716~257~9606
"My Life's A Stage"

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