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Title: Grouding issues and large pools of water
Post by: Clayton Luckie on October 30, 2005, 07:25:42 pm
Hey folks

I just heard news of a pastor who was electrocuted today because he was handed a mic while he was standing in the baptismal.  This is of course a very dangerous thing, especially if there is phantom power on this mic.  

Just a reminder to church tech teams out there that we can do a lot to protect people when micing baptisms.  I use an SM81 just outside of the water area, but far enough away that it would not easily fall into the water.  I also put a windscreen on it, just in case someone decides to grab the mic while standing in the pool.  This would hopefully keep water from reaching the mic element and completing the circuit through the pastor.  

Most importantly, I remind whoever the pastor is that the mic is not to be touched while they are in the water.  

Please be safe when working with this stuff.  Sometimes we can forget how dangerous things can be.  

[Update] I just read that this pastor has passed away because of this accident.  This is serious stuff, folks.  Please be careful.

I also want to say that I do not want to mention the name of this church, because I do not want to bring any undue grief to them in this time.  This message is not at all an indictment of the tech team at this church, but just a reminder to us church sound workers to take extra precautions in this area.  If you are at all effected by this pastor's death, I'm sure you will hear through your church.

cl
Title: Re: Phantom power and large pools of water
Post by: Andy Peters on October 30, 2005, 07:51:32 pm
Clayton Luckie wrote on Sun, 30 October 2005 17:25

I just heard news of a pastor who was electrocuted today because he was handed a mic while he was standing in the baptismal.  This is of course a very dangerous thing, especially if there is phantom power on this mic.


I seriously doubt that phantom power was the problem here.

Sounds like an AC mains issue -- a disconnected safety ground somewhere, or incorrect wiring, or something else to put the case of the microphone at a high potential with respect to the baptismal.

I expect a lawsuit will be filed in the near future.

-a
Title: Re: Phantom power and large pools of water
Post by: Ivan Beaver on October 30, 2005, 08:04:45 pm
I agree with Andy.  The problem must have been a grounding issue.  If the pastor touched the case of the mic and got zapped, he would have not had any acces to the phantom power.  WHile phantom is 48V it's current is very limited.  If driving a dead short there is less than 6ma of current available-due to the series resistors in the console.

I have seen several churches that rely on volunteers to help wire the building.  I have seen reversed hot and neutrals among other errors.  I have repaired lots of equipment that has been fried due to the wiring errors.  Luckily nobody has been hurt yet.  Lots of melted wires though.

People have to look at the REAL problem and not jump to conclusions.  Linda like the time that a famous female singer "almost got electructed when she fell into a pool and was wearing a wireless mic".  They didn't say what brand was being used, but I bet there was no more than 9V in there.  Yeah-that is going to kill ya. Laughing
Title: Re: Phantom power and large pools of water
Post by: Clayton Luckie on October 30, 2005, 08:33:43 pm
Thanks for clarifying the issue here.  I am still learning a lot about AC power, so please keep your thoughts coming.  I guess this could be akin to the "guitarist gets electrocuted when grabbing a mic" problem?  I guess multiply that by standing in a pool...

My main advice remains, however.  I would not in any circumstance hand a wired mic to someone standing in water.  There is just too much at risk.  Wireless, yes (if you are okay risking the life of your wireless mic), but not wired.  Can't be too careful, right?  I find it easy to mic a baptism from a safe distance with a good condenser.  

cl
Title: Re: Phantom power and large pools of water
Post by: Gary Welker on October 30, 2005, 08:55:38 pm
When I do sound for baptisms, I always use a wireless mic on astand.  I do not want anybody going to see the Lord before their time.  I will not put a wired mic anywhere close to the tank.  There are too many risks.  It is just too easy for the pastor or the baptisee to forget and try to grab the mic so that they can speak or give their testimony.  DO NOT USE A WIRED MIC ANYWHERE CLOSE TO A WATER TANK.  Also, please check the grounding of your system.  Look for any 3-2 ground adapters and remove them.  THEY ARE DANGEROUS.

Gary Welker
Title: Re: Phantom power and large pools of water
Post by: John Roberts {JR} on October 30, 2005, 09:22:38 pm
Clayton Luckie wrote on Sun, 30 October 2005 18:25

Hey folks

I just heard news of a pastor who was electrocuted today because he was handed a mic while he was standing in the baptismal.  This is of course a very dangerous thing, especially if there is phantom power on this mic.  

Just a reminder to church tech teams out there that we can do a lot to protect people when micing baptisms.  I use an SM81 just outside of the water area, but far enough away that it would not easily fall into the water.  I also put a windscreen on it, just in case someone decides to grab the mic while standing in the pool.  This would hopefully keep water from reaching the mic element and completing the circuit through the pastor.  

Most importantly, I remind whoever the pastor is that the mic is not to be touched while they are in the water.  

Please be safe when working with this stuff.  Sometimes we can forget how dangerous things can be.  

[Update] I just read that this pastor has passed away because of this accident.  This is serious stuff, folks.  Please be careful.

I also want to say that I do not want to mention the name of this church, because I do not want to bring any undue grief to them in this time.  This message is not at all an indictment of the tech team at this church, but just a reminder to us church sound workers to take extra precautions in this area.  If you are at all effected by this pastor's death, I'm sure you will hear through your church.

cl



I recall hearing about vaguely similar case some ten years ago involving a baptism pool death via wired microphone. In that case the problem was traced to a faulty repair to a powered mixer (thankfully, not my old employer) where some apparently very stupid individual corrected a hum problem by lifting the line cord ground lead inside the unit. I don't know the details but I suspect faulty insulation in the power transformer primary was causing the hum and the line cord safety ground was doing it's job.

IT IS NEVER OK TO REMOVE A SAFETY GROUND. Hum is evidence of current flow, often harmless but sometime deadly. Even with properly designed and maintained equipment, I'd be inclined to opt for wireless when water is involved. Cheap wireless these days makes it a no brainer.


edit - Another though. The source of the dangerous voltage may have been anything associated with the water (pump motor, pool lights, etc). The hard wired microphone would then become the low impedance path to a solid ground. Pools should be GFI protected but who knows where the problem came from.  

JR
Title: Re: Phantom power and large pools of water
Post by: JimCreegan on October 30, 2005, 09:57:09 pm
It might be worthwhile to invest in some ground fault circuit breakers or outlets (they are required around regular bathtubs).  Especially if you can't swing a wireless

JimC
Title: Re: Phantom power and large pools of water
Post by: Stephen B. on October 31, 2005, 10:17:03 am
This is a very tragic thing that has happened.  I find it really hard to believe that this church would have had a bad wiring job considering their permanent worship leader is one of the giants of contemporary worship music.  How much more serious are the ramifications if the church was wired professionally?

Remember that right now here in Waco, we are primarily concerned with supporting the family and friends of the pastor with prayer and love.
Title: Re: Grouding issues and large pools of water
Post by: Clayton Luckie on October 31, 2005, 10:38:23 am
Stephen

If the fault is found to be in the professional wiring, I assume that there can be a law suit against the install company, if they wish to file one.  If the fault is in something else (like the pool), and was a fluke, then I assume this will be chalked up to a horrible accident.  Anyway, I'm sure the church will investigate the cause.

Do you go to this church?

cl
Title: Re: Phantom power and large pools of water
Post by: Mark Smith on October 31, 2005, 10:51:52 am
Foremost our thoughts and prayers are with the family of the minister.  
Second, I think we have to take a serious look at this and determine what happened.  My guess is that it was a light or more likely a heater problem that manifested itself when he touched the mic and grounded himself.  I imagine someone did maintenance on the baptistry or some subset of it over the last few weeks without understanding the implications of everything they did.  We need to all pay close attention to changes in our churches and watch out for unsafe practices.  This was a terrible thing and the way we can pay our respects is to make sure it doesn't happen again.
Title: Re: Phantom power and large pools of water
Post by: glasgowsoundman on October 31, 2005, 10:53:04 am
We just had our own baptismal service on Sunday morning. When we do baptisms, all the introduction/interview/testimony part happens before anyone gets in to the pool. No microphones, wired or wireless, get anywhere near the baptism pool.

My thoughts and prayers are with all those affected by this tragedy.

Regards,

Duncan
Title: Re: Grouding issues and large pools of water
Post by: Mark Smith on October 31, 2005, 11:01:45 am
I don't think this could be a "fluke".  I believe it was a mistake by someone either in the installation or a recent repair.  A properly installed grounding system would not allow this to happen.  I imagine another alternative is that the installation could be old enough that it supersedes some of the ground fault codes.  But something had to degrade in the system to cause this even if this is true.  
Title: Re: Grouding issues and large pools of water
Post by: Stephen B. on October 31, 2005, 11:09:07 am
Clayton Luckie wrote on Mon, 31 October 2005 09:38


Do you go to this church?

cl



No, I don't, but I did an internship with the pastor a few years ago.  He was a very cool guy and will be missed by his congregation.  Waco really seems to attract some tragic occurences.
Title: Re: Phantom power and large pools of water
Post by: Lee Patzius on October 31, 2005, 11:13:16 am
Stephen B. wrote on Mon, 31 October 2005 10:17

This is a very tragic thing that has happened.  I find it really hard to believe that this church would have had a bad wiring job considering their permanent worship leader is one of the giants of contemporary worship music.  How much more serious are the ramifications if the church was wired professionally?

Remember that right now here in Waco, we are primarily concerned with supporting the family and friends of the pastor with prayer and love.


You can actually have a good grounded system, but still get between two grounds separated by distance and source, and experience a shock.

Otherwise we'd never have hum.

A properly installed GFCI helps prevent these kinds of tragedies.
Title: Re: Phantom power and large pools of water
Post by: Mark Smith on October 31, 2005, 12:12:20 pm
While ground loops can cause hum, I can't think of a situation where you could have enough current capacity to cause a problem...  Maybe with two completely seperate services and grounding systems, but you still usually have no more than a couple of ohms impedance between the two grounds and that is an outside number.  Any thoughts?
Title: Re: Grouding issues and large pools of water
Post by: Marty McCann on October 31, 2005, 12:43:49 pm
More than likely a gray cheater gounding adapter was put into the system and not grounded, or perhaps someone cut off the third or ground pin on an AC cord.  It only takes 15 milliampere to kill.

marty
Title: Re: Phantom power and large pools of water
Post by: JimCreegan on October 31, 2005, 12:43:58 pm
If a hot is connected to a ground (through a fault) with enough resistance to avoid a blown circuit that current will go to any ground avaliable.  It takes less than you may think to kill.

http://www.smud.org/safety/world/hurt/chart.html

Sacramento Municipal Utility District

A milliamp is 1/1000th of an ampere, a measure of electricity.

   * A person can just feel less than 5 milliamps of electrical current.
   * A person can't let go of an object with 5 to 20 milliamps of electrical current.
   * 20 to 60 milliamps of electric current is possibly fatal.
   * 60 to 8000 milliamps of electric current is probably fatal.

A GFCI is a Ground Fault Circuit Interrupter, a device which protects against serious shock. The trip setting for a GFCI is less than 5 milliamps.

JimC
Title: Re: Phantom power and large pools of water
Post by: Lee Patzius on October 31, 2005, 12:58:17 pm
Mark Smith wrote on Mon, 31 October 2005 12:12

While ground loops can cause hum, I can't think of a situation where you could have enough current capacity to cause a problem...  Maybe with two completely seperate services and grounding systems, but you still usually have no more than a couple of ohms impedance between the two grounds and that is an outside number.  Any thoughts?


Yeah, in the church scenario, two grounds with enough current to kill may sound far fetched until you realize 20 to 50 milliamps is all it takes.

Then add water. Body resistance drops extremely low.

Add voltage to a wet human body, conductivity is sure to increase (resistance drops). Much like an arc through air as an analogy, air measures near infinity Ohms until broken down by conduction of an arc.  

Not to mention the capacitance in the body too. It passes AC.

Even 1 volt, at 1 ohm, kills a person 20 times over.

My initial response was aimed at what could've possibly gone wrong on a professionally installed system.

NOTE! Even with GFCI's, if it WERE two grounds, it IS possible that a GFCI would NOT have helped, because the grounds don't get interrupted by the GFCI. Nor do grounds get interrupted by circuit breakers.

Far fetched? Not when a person is touching an electrical object in a pool of water.

This is one situation of the "flip side of the coin" where grounding can actually kill. Had the power system been floating, (such as an ungrounded balanced 120 Volt system) or, had the mic been ungrounded, there would have been zero potential as he charged the mic case.  

But in the above paragraph, unbalanced/ungrounded 120 volt systems do not exist. So we MUST keep things grounded. Or someone else will eventually energize it high, or sink it to ground for you. We dedicate the grounding conductor, and keep it standardized.

The most likely situation is that the pool became energized hotter than the mic ground, and he got killed. The mic was most likely grounded through audio shields, even IF a power ground lift adapter was used somewhere. Case grounds, audio shields,  and metal enclosures always seem to find earth one way or another. A GFCI WOULD have helped in this "likely" situation.


Title: Re: Grouding issues and large pools of water
Post by: Bennett Prescott on October 31, 2005, 01:10:44 pm
There was just a very heated and lengthy discussion on this in the LAB. It's very sad to see it play out again in this format so soon.

For those of you looking for a quick "here's how grounding works" cheat sheet, I've posted a moderately comprehensive set of guides in the downloads section of my website... the first link is to an excellent presentation by Bill Whitlock that is slowly but surely opening the minds of sound engineers everywhere.

http://www.campuspa.com/downloads/downloads.html

[edit: can't link right to my own website... what am I coming to?]
Title: Re: Phantom power and large pools of water
Post by: Mark Smith on October 31, 2005, 01:27:30 pm
my comment was referencing ground loops that cause hum. Since the different grounding systems have a maximum impedance of about 15 ohms (making assumption both are "grounded")and the body has a minimum wet resistance of about 1000 ohms, only 1.5% of the current goes through the body. Since we are dealing with 2 GROUNDING systems, not a hot, the voltage difference between the two systems would have to be a minimum of 1,319.5 volts. I don't know of a situation where you would see this.  Reference on the body resistance:
http://www.osha.gov/SLTC/etools/construction/electrical_inci dents/eleccurrent.html

Unfortunately I think we saw a main power contact here and it is sad that it happen.
Title: Re: Grouding issues and large pools of water
Post by: Mark Smith on October 31, 2005, 01:30:20 pm
I don't know about the lab, but I think here we really are trying to understand what happened and hopefully learning how to make sure this tragedy doesn't happen again.  The important thing for all of us to remember is no matter the cause, someone lost their life and that is truly regretable.
Title: Re: Grouding issues and large pools of water
Post by: John Roberts {JR} on October 31, 2005, 02:13:37 pm
Mark Smith wrote on Mon, 31 October 2005 12:30

I don't know about the lab, but I think here we really are trying to understand what happened and hopefully learning how to make sure this tragedy doesn't happen again.  The important thing for all of us to remember is no matter the cause, someone lost their life and that is truly regretable.


Agreed... we are all guessing at this point. The instructive point is despite all the safety systems and practices available, another person just died, RIP.

The follow up report should be informative.

JR
Title: Re: Phantom power and large pools of water
Post by: Lee Patzius on October 31, 2005, 02:37:32 pm
Mark Smith wrote on Mon, 31 October 2005 13:27

Since the different grounding systems have a maximum impedance of about 15 ohms (making assumption both are "grounded")and the body has a minimum wet resistance of about 1000 ohms, only 1.5% of the current goes through the body.


I won't challenge your 1000 Ohm "wet" reference too much. But in my opinion, I totally disagree. The body resistance figures in the reference has mostly nothing to do with a human submersed in water. I suspect it must be referring to point-to-point series resistance, or more likely, probe tip, to probe tip, with wet fingers? And, that figure was probably obtained with a standard high dollar, low volt ohmmeter, like the one sitting next to me.

DO NOT TRY THIS... But a "meg-ohmmeter" on a human body submersed in water would probably be more accurate, but then it would probably kill them, if it put out 50 milliamps. The meg-ohmmeter puts out high voltage. We use meg-ohmmeters to inject high voltage to test and measure insulation integrity. Regular meters show infinite Ohms, while meg-ohmmeters display a whole new story. They show the actual resistance as insulation breaks down, when subjected to high voltage.

Also, we're dealing with human submersion and wet skin. Way more surface contact, way less resistance. Way less voltage required to shock... In my honest opinion.

Quote:

Since we are dealing with 2 GROUNDING systems, not a hot, the voltage difference between the two systems would have to be a minimum of 1,319.5 volts. I don't know of a situation where you would see this.


In 30 some-odd years, I've blown sparks between two grounds on a few, but very rare occasions. (I know... Regardless, I can blow sparks on a 12 volt car battery too.) And I've seen hot grounds NOT blow breakers too. Each situation is totally different.

Quote:

Unfortunately I think we saw a main power contact here and it is sad that it happen.


Yes, I absolutely agree. I suspect the same.
Title: Re: Phantom power and large pools of water
Post by: Mark Smith on October 31, 2005, 04:07:44 pm
very good point... if the water is energized (or is the ground) then there is a lot of surface contact, so I don't know how accurate my 1 kohm number is.
With your insulation statement, My understanding of insulation is that it has an almost infinite impedance up to it's breakdown voltage.  At that point the characteristics change.
I have seen grounds spark over too, but not in a situation where 120/240 is the primary voltage on the system. (saw it on 161 kV and it was a bad day)
Thanks for replying, I consider this one of the ways I will learn more.
Title: Circuit tester?
Post by: Nathan Lehouillier on October 31, 2005, 04:51:47 pm
I own 20+ of these little guys and have advised every one that works with me that they must check every thing they plug into every show. http://www.tripplite.com/products/static/ct120.cfm
Safety measure's are not optional.
Nathan KDS&L
Title: Re: Phantom power and large pools of water
Post by: Lee Patzius on October 31, 2005, 11:24:50 pm
Mark Smith wrote on Mon, 31 October 2005 16:07

 
With your insulation statement, My understanding of insulation is that it has an almost infinite impedance up to it's breakdown voltage.  At that point the characteristics change.


Generally speaking, insulation has a very high resistance to DC, but much lower impedance to AC. I suspect we humans conduct pretty much the same way.

Quote:

I have seen grounds spark over too, but not in a situation where 120/240 is the primary voltage on the system. (saw it on 161 kV and it was a bad day)



Whoa! Yeah that makes for a really bad day.

One night, out the corner of my eye, I saw a momentary flash of lightning balls coming out of the earth, inside a 34.5kV substation yard. Everything was still running smooth. I reported it, and they laughed about it for a good couple of days, until an underground 3600 Volt (IIR) feeder line blew up. We called in the big rigs for that job.
Title: Re: Grouding issues and large pools of water
Post by: Steve Olsen on November 01, 2005, 10:56:00 am
Unfortunate accidents like this really bring home the need know and follow all existing safety standards. I have been an electrician for over 35 years, a musician for "a little longer", and an instructor for about 10 years (those that can't do, teach?)

I have assisted in investigations similar to the accident discussed here. There are literally 100's of possible scenario's that can result in death. As techs we have a duty to be as educated and conscientious as possible.

Personally, I have always had an issue with using ground lifts and with using nonprofessional (2 wire) AC connections (CD players, tape decks, vintage amplifiers, ...). In larger installations, it is common to have more than one point of entry and more than one ground potential. On their own they can be perfectly safe and be within NEC spec. When combined they become a loaded gun.

Please keep safety in mind even if you're short on setup time. And please think twice before using ground lifts.
Title: Re: Grouding issues and large pools of water
Post by: Dave Hudzik on November 02, 2005, 01:13:43 am
not the greatest choice of words by another pastor...  Please no one think I am taking this as lightly, this was someones life.

“We're all in a state of shock,” said the Rev. Joel Gregory, professor of preaching at Baylor University's Truett Seminary. “I have never encountered this (kind of accident) in all my years of ministry.”
Title: Re: Grouding issues and large pools of water
Post by: Guest on November 02, 2005, 03:42:03 pm
I will bet that many churches will review their configuration  for baptisary mic's in light of this unfortunate accident. Many will assume that since they aren't using phantom power that all is OK (obviously a misnomer).

But it appears that the only fully safe solution would be the wireless mic on a boom. A second would be a hanging condensor choir mic, well out of reach.

Am I missing something?
Title: Mic level isolation transformer
Post by: Michael 'Bink' Knowles on November 02, 2005, 03:52:06 pm
Mike McCloskey wrote on Wed, 02 November 2005 12:42

I will bet that many churches will review their configuration  for baptisary mic's in light of this unfortunate accident. Many will assume that since they aren't using phantom power that all is OK (obviously a misnomer).

But it appears that the only fully safe solution would be the wireless mic on a boom. A second would be a hanging condensor choir mic, well out of reach.

Am I missing something?


At least one more safe solution to the problem would be a wired dynamic mic connected to the mixer through an isolation transformer with pin 1 not connected and its housing not grounded.

-Bink
Title: Re: Mic level isolation transformer
Post by: William Nexsen on November 02, 2005, 04:10:45 pm
Agreed, Bink, except this situation needs to be idiot-proof.  As the memory of this event fades, someone will, in time, move or replace the mike/xformer/pin-1-lifted-cable and discover that it was really all unnecessary and replace it with an off-the-shelf mike cable and skip the isolation xformer.  Everything will be fine until somewhere a fault develops, and another preacher gets killed.
I'm sending a copy of the article to all my clients who dunk along with a recomendation they use only a wireless in the font and the reasoning behind this.
Title: Re: Mic level isolation transformer
Post by: glasgowsoundman on November 02, 2005, 04:41:31 pm
Michael 'Bink' Knowles wrote on Wed, 02 November 2005 20:52

Mike McCloskey wrote on Wed, 02 November 2005 12:42

I will bet that many churches will review their configuration  for baptisary mic's in light of this unfortunate accident. Many will assume that since they aren't using phantom power that all is OK (obviously a misnomer).

But it appears that the only fully safe solution would be the wireless mic on a boom. A second would be a hanging condensor choir mic, well out of reach.

Am I missing something?


At least one more safe solution to the problem would be a wired dynamic mic connected to the mixer through an isolation transformer with pin 1 not connected and its housing not grounded.

-Bink



Feels weird to quote myself, but another solution would be to alter the format of the baptisms.

http://srforums.prosoundweb.com/index.php/m/84698/6165/?SQ=a 2abc79b3e6910a4881776a121f63e09#msg_84698

Regards,

Duncan
Title: Re: Grouding issues and large pools of water
Post by: Preston Edwards on November 02, 2005, 05:03:15 pm
I've been a lurking member here for a few months but just haven't posted much.  Embarassed

I am a college student at Baylor University and was present at this church on Sunday when it happened. While a terrible tragedy no doubt, I have had numerous calls and e-mails from churches that I have done A/V work for wanting to know what they can do to make sure this doesn't happen at their place of worship. This is a good thing, as people are becoming more aware as to the dangers of improperly grounded systems and wired components next to water.

As many have said in this thread, use a lapel wireless mic if you're ever in this situation. If one's not available, make sure the mic you're using is positioned so that it cannot come into contact with the water or the person in the water. The mic in this case was much too close and was too easily manipulated to be anywhere near safe.

As many have also said, in my experience as Director of Media at a large church in San Antonio, churches typically cut corners and have to deal with volunteers, etc., and so this type of thing, while unfortunate, has the potential to happen more often than it does. In this case it was a pastor, but it could have been anyone that triggered conditions exposing the fault.

As most of us have heard: Lose a neutral, lose some equipment; lose a ground, lose a life.

My heart goes out to the family and to the church as they struggle with how to proceed in the future.
Title: Re: Grouding issues and large pools of water
Post by: John Roberts {JR} on November 02, 2005, 05:09:49 pm
Mike McCloskey wrote on Wed, 02 November 2005 14:42

I will bet that many churches will review their configuration  for baptisary mic's in light of this unfortunate accident. Many will assume that since they aren't using phantom power that all is OK (obviously a misnomer).

But it appears that the only fully safe solution would be the wireless mic on a boom. A second would be a hanging condensor choir mic, well out of reach.

Am I missing something?


Agreed, as previously stated a wireless mic seems eminently appropriate for this situation and this has happened before.

Water needs to be respected as a low impedance path for hazardous currents, which for the record we are still speculating about the source of.

JR
Title: Re: Grouding issues and large pools of water
Post by: William Nexsen on November 02, 2005, 05:53:07 pm
In the quest for an idiot-proof solution, one thought might be to install a mike jack in a location convenient to the bapistry incorporating Bink's suggestion of transformer isolation that's permanently installed out of sight behind the mike jack.  It isn't completely bulletproof, but would probably work until the church redesigned their baptistry...
Title: Re: Grouding issues and large pools of water
Post by: John Roberts {JR} on November 02, 2005, 06:31:27 pm
william wrote on Wed, 02 November 2005 16:53

In the quest for an idiot-proof solution, one thought might be to install a mike jack in a location convenient to the bapistry incorporating Bink's suggestion of transformer isolation that's permanently installed out of sight behind the mike jack.  It isn't completely bulletproof, but would probably work until the church redesigned their baptistry...


I recall reading a book years ago called something like the "science of failure" (?) I don't recall the exact title but it was basically a study of why systems or plans failed and it comes down to "factors" that aren't properly evaluated and considered. The problem with making a system "idiot proof" is that the idiots evolve and find ways to get around your idiot proofing.

I still think wireless mics, as cheap as they are these days, are pretty hard to become a shock hazard unless you hold one over your head while standing on a hill top during a thunderstorm. It's not about mitigating the mistakes you can imagine but protecting against the ones you haven't.

JR
Title: Re: Grouding issues and large pools of water
Post by: DTownSMR on November 03, 2005, 01:44:50 pm
I'll show my ignorance here. Would placing the mixing desk (or whatever is connected to the jacks on the chancel/stage) on a GFI circuit prevent such a tragedy?
Title: Re: Grouding issues and large pools of water
Post by: Guest on November 03, 2005, 02:05:18 pm
NO.  The GFCI would kill power to the mixer. It would NOT help if the power was coming from the other side, such as a fault in the baprisry water heater...
Title: Re: Grouding issues and large pools of water
Post by: Mark Smith on November 03, 2005, 02:34:55 pm
Mike is correct, but are you sure it would kill the power to the mixer?  I thought the gfci looked at the difference in the phase and neutral current, not the ground current itself (if the fault came from another source it may not see it).  I could be wrong on this.
Title: Re: Grouding issues and large pools of water
Post by: Guest on November 03, 2005, 03:17:45 pm
I meant if the fault were on the mixer's side (power to the SR equipment.)making the mic 'hot' and the pool the ground. Not if the pool was acting as the 'hot' and the mic was the ground.

Not an electrician, don't play one on TV, so open to correction!
Title: Re: Grouding issues and large pools of water
Post by: John Roberts {JR} on November 03, 2005, 05:37:01 pm
DTownSMR wrote on Thu, 03 November 2005 12:44

I'll show my ignorance here. Would placing the mixing desk (or whatever is connected to the jacks on the chancel/stage) on a GFI circuit prevent such a tragedy?

I believe we are all ignorant regarding what actually caused this specific fault condition therefore speculating about mitigating any one of the sundry possible faults might be ineffective.

If you are still using a hardwired mic (why?) around water, you need to insure all involved safety systems are the latest technology, in place and working. I won't repeat the sundry possible fault scenarios.


JR
Title: Re: Grouding issues and large pools of water
Post by: William Nexsen on November 03, 2005, 06:16:28 pm
JR--You're right, of course.  I was way too quick posting my response to Bink's well thought out "fix", and didn't mean to imply that Bink wasn't aware of the impossibility of an absolute fix.  As you and others have pointed out, there is a constellation of things that, taken individually are each Ok and even within code; but when they all line up just right can lead to serious or even fatal consequences.
The scary thing is that even if we all communicate this event to all of clients who practice full immersion baptisms (and I  feel obligated to do just that) this will still happen again.  In a couple of years people will have forgotten...
Title: Re: Grouding issues and large pools of water
Post by: John Roberts {JR} on November 03, 2005, 10:10:11 pm
william wrote on Thu, 03 November 2005 17:16

JR--You're right, of course.  I was way too quick posting my response to Bink's well thought out "fix", and didn't mean to imply that Bink wasn't aware of the impossibility of an absolute fix.  As you and others have pointed out, there is a constellation of things that, taken individually are each Ok and even within code; but when they all line up just right can lead to serious or even fatal consequences.
The scary thing is that even if we all communicate this event to all of clients who practice full immersion baptisms (and I  feel obligated to do just that) this will still happen again.  In a couple of years people will have forgotten...


Wireless mics but not during thunderstorms on hill tops.

JR
Title: Re: Grouding issues and large pools of water
Post by: JimCreegan on November 04, 2005, 02:27:47 am
DTownSMR wrote on Thu, 03 November 2005 13:44

I'll show my ignorance here. Would placing the mixing desk (or whatever is connected to the jacks on the chancel/stage) on a GFI circuit prevent such a tragedy?


Of course it would be absolutely illegal to have any power on the pool not on GFCI, so if everything the sound system was plugged into was also GFCI protected you would be safe, unless one of the GFCIs failed.  
Nine volts on a wireless battery has probably only caused a tingle on the tongue of a sound tech with no voltmeter handy, nothing more.

JimC
Title: Re: Grouding issues and large pools of water
Post by: Mark Smith on November 04, 2005, 08:17:20 am
JimCreegan wrote on Fri, 04 November 2005 02:27



Of course it would be absolutely illegal to have any power on the pool not on GFCI, so if everything the sound system was plugged into was also GFCI protected you would be safe, unless one of the GFCIs failed.  
Nine volts on a wireless battery has probably only caused a tingle on the tongue of a sound tech with no voltmeter handy, nothing more.

JimC


I think it is a stretch to say it is safe.  While under perfect circumstances it would work that way, here are a few things to think about.
1. If different electrical service entrances exist, different grounding systems may be in place (technically I argued against this one earlier, so I don't have much of a leg to stand on here, but thought I would bring it up)

2. It is only illegal if the building was built or renovated after the GFCI code came into existance (just like a house built 10 years ago is still "legal" if it doesn't have arc flash outlets in bedrooms).  

3. From my experience, there are too many people that "work on" things in most churches to run the risk of a GFCI not being installed correctly or a ground not being lifted by a well intentioned volunteer. Even the "professionals" occassionally make a mistake.

4. The lessons of this incident will fade over time.  While due dilligence may be used right now to double check everything on this, in a few years people will go back to the way they have always done things.  Example: How often do you test the GFCI outlets in your house?  Do you know they work or are installed right?

As for me, it is much easier to limit anything around the baptistry to wireless.  It makes my life simplier to not have to worry about what could happen.

regards.
Title: Re: Grouding issues and large pools of water
Post by: JimCreegan on November 04, 2005, 09:06:53 am
Mark Smith wrote on Fri, 04 November 2005 08:17

JimCreegan wrote on Fri, 04 November 2005 02:27



unless one of the GFCIs failed.  

Nine volts on a wireless battery has probably only caused a tingle on the tongue of a sound tech with no voltmeter handy, nothing more.

JimC



As for me, it is much easier to limit anything around the baptistry to wireless.  It makes my life simplier to not have to worry about what could happen.

regards.


Exactly my point, and it seems a consensus.  

The other thing to think about though, is if there are baptismals or any pools, hot tubs, whatever, around that have mains power,  installed before the GFCI regulations they need to be updated.

JimC
Title: Re: Grouding issues and large pools of water
Post by: DTownSMR on November 04, 2005, 09:42:35 am
Unless you have a fool proof plan as to how to eliminate every  possibility of ever having any and all mic (re: input) jacks within reach of any and all chords ever used, it's impossible to "limit anything around the baptistry to wireless". The best you can hope for is to limit the "planned" anything to wireless.
Title: Re: Grouding issues and large pools of water
Post by: Guest on November 04, 2005, 03:06:49 pm
Quote:

course it would be absolutely illegal to have any power on the pool not on GFCI


I am no electrician, but I think that a GFCI might not be required by code. A recept ocer the pool would have to be, but not the heater.
Title: Re: Grouding issues and large pools of water
Post by: JimCreegan on November 04, 2005, 03:12:58 pm
Mike McCloskey wrote on Fri, 04 November 2005 15:06

Quote:

course it would be absolutely illegal to have any power on the pool not on GFCI


I am no electrician, but I think that a GFCI might not be required by code. A recept ocer the pool would have to be, but not the heater.


http://www.electrical-contractor.net/ESF/GFCI_Protection-Poo ls-Hot_Tubs.htm

It seems that you were right until recently.  I thought this went back a lot further.

JimC
Title: Re: Grouding issues and large pools of water
Post by: Michael 'Bink' Knowles on November 04, 2005, 04:47:00 pm
It wasn't THAT well thought-out.  Confused   ...just one more option for solving the problem.

If you have a wall plate XLR jack with a mic-level isolation transformer hidden inside and mounted near the pool of water then you'll have a safe, wired option on that one day when all of a sudden none of your wireless mics are working. Until then, use a wireless.

-Bink
Title: Re: Phantom power and large pools of water
Post by: Scott Raymond (Scott R) on November 04, 2005, 06:36:19 pm
Stephen B. wrote on Mon, 31 October 2005 09:17

This is a very tragic thing that has happened.  I find it really hard to believe that this church would have had a bad wiring job considering their permanent worship leader is one of the giants of contemporary worship music.  How much more serious are the ramifications if the church was wired professionally?

Remember that right now here in Waco, we are primarily concerned with supporting the family and friends of the pastor with prayer and love.


When I saw Waco, my thoughts went to David C.  Is this who your refering to?  He's been here in the theatre.  Our prayers go out to everyone there.  
Title: Re: Phantom power and large pools of water
Post by: Clayton Luckie on November 04, 2005, 06:50:49 pm
Scott R (Raymond) wrote on Fri, 04 November 2005 17:36

Stephen B. wrote on Mon, 31 October 2005 09:17

This is a very tragic thing that has happened.  I find it really hard to believe that this church would have had a bad wiring job considering their permanent worship leader is one of the giants of contemporary worship music.  How much more serious are the ramifications if the church was wired professionally?

Remember that right now here in Waco, we are primarily concerned with supporting the family and friends of the pastor with prayer and love.


When I saw Waco, my thoughts went to David C.  Is this who your refering to?  He's been here in the theatre.  Our prayers go out to everyone there.  


Yes, the remaining staff members are David Crowder (worship leader) and two other people.  Please pray for them as they take on a lot of extra stress and work.

cl
Title: Re: Grouding issues and large pools of water
Post by: Scott Raymond (Scott R) on November 04, 2005, 07:07:42 pm
JimCreegan wrote on Fri, 04 November 2005 08:06

Mark Smith wrote on Fri, 04 November 2005 08:17

JimCreegan wrote on Fri, 04 November 2005 02:27



unless one of the GFCIs failed.  

Nine volts on a wireless battery has probably only caused a tingle on the tongue of a sound tech with no voltmeter handy, nothing more.

JimC



As for me, it is much easier to limit anything around the baptistry to wireless.  It makes my life simplier to not have to worry about what could happen.

regards.


Exactly my point, and it seems a consensus.  

The other thing to think about though, is if there are baptismals or any pools, hot tubs, whatever, around that have mains power,  installed before the GFCI regulations they need to be updated.

JimC




Good point Jum.  We always use a wirless, even if they don't iintend on picking up the mic.  But the GFCI I'm not sure about.  Our church was built over 20 years ago and I'm guessing the heater doesn't have a GFCI.  With a baptismal service coming up soon that's a concern with this tragic reminder.  One could even speculate that baptismals that are drained after every use could be more suspect to corrosion than spa's and pools that are in service on a constant basis.
Title: Re: Grouding issues and large pools of water
Post by: Steve Swaffer on November 05, 2005, 08:59:04 pm
A lot of good comments so far.  I am a licensed master electrician and have been a "weekend warrior" sound tech for 12 years.  My suspicion would lie first with either a faulty heater or pump on the baptistry which would go undetected until someone provided a ground path-and a properly installed sound system would provide just that ground.  Baptistries are not mentioned in the code(but a few accidents like this and they might be-that is what drives the code), so depending on which section the inspector thought applied he might or might not require a GFCI.  I just looked at our baptistry today and like I expected it is all fiberglass/PVC so no grounds to trip a breaker in case of a fault.  Wireless mics are certainly a good idea, but in my opinion, a GFCI breaker on the baptistry equipment is morally if not legally required-there are too many other potential ground paths (like someone standing on a damp floor,etc, etc).  My wholesale cost for the proper breaker for ours is $154 vs around $30 for a standard breaker.  A lot of money until compared to the value of a life.  By the way, ours was installed by a professional (not me!)-don't assume they did it right!
Title: Re: Grouding issues and large pools of water
Post by: Marty McCann on November 07, 2005, 10:51:52 am
A music dealer in Waco reported the following regarding this thread:

>>> "xxx xxxxxx - xxxxxxx" <xxxxxxx@xxxxxxxxxx.com> 11/05/05 12:32PM >>>

The church was wired by members not contractors when it was converted to a church from a safeway.

The wiring was not up to code and caused there to be current
running through the baptistry.

The mike just acted as a ground.
Title: Re: Grouding issues and large pools of water
Post by: Ron Riedel on November 07, 2005, 10:53:31 am
Steve S. wrote on Sat, 05 November 2005 18:59

...Wireless mics are certainly a good idea, but in my opinion, a GFCI breaker on the baptistry equipment is morally if not legally required-there are too many other potential ground paths (like someone standing on a damp floor,etc, etc).  My wholesale cost for the proper breaker for ours is $154 vs around $30 for a standard breaker.  A lot of money until compared to the value of a life.  By the way, ours was installed by a professional (not me!)-don't assume they did it right!


I agree completely. What does a baptistry cost to install, anyway? $5K-$10K at least? I don't see where an extra $125 for GFCI protection is all that expensive, and I can't imagine anyone doing an install without one. I wouldn't allow anyone to install a hot tub in my home without GFCI protection, either. I don't care what the code says.

As I've posted elsewhere on this board, we do worship outdoors in the summer. I power our system from a GFCI protected outdoor outlet, the main extension feeder cable has GFCI protection on the outlet boxes, and the equipment cart has additional GFCI protection on the internal outlets which distribute the power to the various components. That's 3 GFCI's in series, and I don't think that's overkill. We never play in the rain, but often the grass is wet from dew or overnight sprinklers, and I feel a lot more comfortable knowing the musicians are protected. I also won't allow anyone to use cords with the safety ground defeated, even indoors. There are no compromises or "we'll get by with it this one time" attitudes allowed when it comes to safety.

Ron

Ron
Title: Re: Grouding issues and large pools of water
Post by: John Roberts {JR} on November 07, 2005, 11:16:55 am
Marty McCann wrote on Mon, 07 November 2005 09:51

A music dealer in Waco reported the following regarding this thread:

>>> "xxx xxxxxx - xxxxxxx" <xxxxxxx@xxxxxxxxxx.com> 11/05/05 12:32PM >>>

The church was wired by members not contractors when it was converted to a church from a safeway.

The wiring was not up to code and caused there to be current
running through the baptistry.

The mike just acted as a ground.



Thanks for the 911. Wireless would help but one could still get zipped getting out with wet feet on concrete floor.

I hope everybody out there reading this will check for GFIs and being to current code.

JR
Title: Re: Grouding issues and large pools of water
Post by: Michael 'Bink' Knowles on November 07, 2005, 11:21:02 am
Quote:

...The church was wired by members not contractors when it was converted to a church from a safeway.

The wiring was not up to code and caused there to be current
running through the baptistry.

The mike just acted as a ground.



That's what a number of us were speculating about--your source seems to confirm that the sound system in question was appropriately grounded. It still doesn't make it okay to put a grounded, wired microphone near water. Which you know, of course...

-Bink
Title: Re: Grouding issues and large pools of water
Post by: Guest on November 07, 2005, 10:33:31 pm
While the information from a local music store is very plausible, and may be well informed, it might be just as accurate as our guessing. Checking the church's websitwe reveals that the cause is as yet to be determined.
Title: Re: Grouding issues and large pools of water
Post by: John Roberts {JR} on November 08, 2005, 07:34:54 am
Mike McCloskey wrote on Mon, 07 November 2005 21:33

While the information from a local music store is very plausible, and may be well informed, it might be just as accurate as our guessing. Checking the church's websitwe reveals that the cause is as yet to be determined.



In situations involving loss of life I would expect parties involved to be thoughtful about public statements that could be construed as assigning blame.

JR
Title: Re: Grouding issues and large pools of water
Post by: JIMGUNDLACH on November 24, 2005, 09:35:06 pm
It's 2005.  Use a wireless mic.  9V bats don't kill people.
Title: Re: Grouding issues and large pools of water
Post by: Andy Peters on November 24, 2005, 11:20:06 pm
JIMGUNDLACH wrote on Thu, 24 November 2005 19:35

It's 2005.  Use a wireless mic.  9V bats don't kill people.


True, but one must assume that the baptismal would've eventually killed someone, even without someone grabbing a microphone while immersed.

Just a matter of time ...

-a