Body
Please understand that in the US there are approximately 400,000
Baptisms performed annually. In most cases there is water and an audio
system involved. There are a lot of electrocutions that we never hear of
as quoted here:
This type of death happens annually. Therefore, sound operators should
be aware of potential electrical hazards associated with sound
reinforcement systems. We have a responsibility for producing quality
sound but also doing so in a safe environment.
/Disclaimer: "Please note this article is meant to discuss safety issues
with baptismal amplification. In no way is it meant to claim cause of or
accuse those involved in any negligence."/
/See: https://www.behindthemixer.com/baptismal-amplification-and-safety//
/I have heard of three such cases while living in Texas. The last was
the Waco Pastor and I find the Court explanation rather lacking in that
a damaged Calrod water heater was to blame. You cannot sue in Court if
the Pastors' own amplifier was to blame so you search for a supposed
responsible party. I don't know, I just read the news and form my own
opinion!/
/https://www.chron.com/news/houston-texas/article/Family-settles-lawsuit-in-electrocution-death-of-1881419.php
/
On 11/4/2018 12:21 PM, Mick [email protected] [EVGRAY] wrote:
>
> Norm,
>
> I really hope that was an accident and not a prank, how awful!
>
> Assuming that was a class AB if push pull as most of the old tube Push
> Pull PA amps were biased AB instead of solid class A due to heat
> dissipation. Single ended up until the push pull current buffer
> because this section requires a phase inverter tube to make it push pull.
>
> Unlikely it still worked with a shorted plate supply cap, probably had
> not been tested in awhile or shorted at the moment.
>
> What a horrible spectacle for a baptism, hope the child was not harmed.
>
>
> On 11/4/2018 5:50 AM, Norman Wootan [email protected] [EVGRAY] wrote:
>>
>> Mick! Your comment about some people dying from pranks! True Story!
>> Back in the early 80s a pastor at a Duncanville Church (suburb of
>> Dallas) was preforming a live Baptism at his church on a typical
>> Sunday morning! His audio amp was the old vintage single end class A
>> push-pull tube amp. As he descended into the Baptism pool in front
>> of congregation and flipped on the hand held mic switch has was
>> instantly fried by 450VDC plate voltage on chassis ground. Coroners
>> report showed that an electrolytic cap in the HVDC plate power supply
>> had gone to ground in effect energizing chassis at the 450VDC
>> potential. All those vintage amps had the old two pin 120VAC plugs
>> before the 3 pin safety grounds we now have.
>>
>> http://www.angelfire.com/electronic/funwithtubes/Amp-Power_Supply.html
>>
>> Having gone through DeVry Electronics back in 1953, I totally
>> understood the lethality of such an event!
>>
>>
>> On 11/3/2018 7:55 PM, Mick [email protected] [EVGRAY] wrote:
>>>
>>> Norm,
>>>
>>> The interconnects used for home audio should be illegal for bad
>>> sound, but even a properly designed mic cable with an XLR on each
>>> end with a hot a cold and a shield one will notice only on female
>>> side the shield connects to the chassis of the connector. It is a
>>> single shield run on #1 to both sides though as the connections are
>>> designed balanced for just the reason you mentioned.
>>>
>>> XLR's are the best connector for long run connections but I make my
>>> own cable with silver plated aircraft cable with teflon insulation,
>>> a pain to work with but sound is great.
>>>
>>> For short single ended runs the RCA end sucks and it should have
>>> been BNC or the extra small microwave connectors that look like mini
>>> BNC's If one removes the RCA connectors and replaces with BNC and
>>> high quality aircraft cable and the rest of the gear is good enough
>>> one will notice the difference. Networking cable Cat 5 or 6 can
>>> also sound great as speaker cable.
>>>
>>> The story gets worse though as the old tube guitar amp had a switch
>>> that would toggle chassis ground between either connector on the
>>> power connection for the purpose of preventing ground loops when
>>> some live show venue had the outlets wired with hot and neutral
>>> reversed. Well when that guitarist also happens to be a vocalist
>>> and touched a mic stand with the ground switched wrong it was not
>>> pretty if the shield was run to both chassis of the connectors.
>>> This was an old soundman trick to get back at the rude ego asshole
>>> guitar players using the special fully grounded mic cable. I am
>>> sure some people died from this prank where 220 was used.
>>>
>>>
>>> On 11/3/2018 4:46 PM, Norman Wootan [email protected] [EVGRAY] wrote:
>>>>
>>>> Mick! Just had to laugh at your remark about floating grounds in
>>>> the recording studio! Ha! Ha! Way back when I was learning about
>>>> fine audio, I ran a shielded line level audio cable to hook two
>>>> sound systems together, about 100 ft run. When I turned on the
>>>> systems and selected line in on the 2nd system, I had the prettiest
>>>> motor boat you ever heard! Lol Yep! I had grounded both ends of a
>>>> shielded cable and got a good example of a ground loop!
>>>>
>>>>
>>>> On 11/3/2018 4:54 PM, Mick [email protected] [EVGRAY] wrote:
>>>>>
>>>>> Norm,
>>>>>
>>>>> Thanks for that.
>>>>>
>>>>> I love Mr Calrsons lab, I could happily live there for quite
>>>>> awhile with all that awesome vintage gear. I have seen isolation
>>>>> transformers wired like that and it's so insane but I am used to
>>>>> testing all the grounding points. When building a recording
>>>>> studio we have to float all the grounds so they are single point
>>>>> at the service panel and not looped anywhere else. Often they are
>>>>> lifted at the outlet j-box due to the lack of control in a
>>>>> prewired building. Ironically we also used to use autoformers for
>>>>> all of the light dimmers to prevent noise, so we often referred to
>>>>> the variacs as light dimmers.
>>>>>
>>>>> I still don't completely trust a scope on an isolation transformer
>>>>> even if the ground is properly isolated/ lifted due to the
>>>>> somewhat rare magnetic emp events we are talking about like when I
>>>>> kicked off all my ground faults in the house through one.
>>>>>
>>>>>
>>>>> On 11/3/2018 2:03 PM, Norman Wootan [email protected] [EVGRAY] wrote:
>>>>>>
>>>>>> Mick! Here is a helpful video regarding scopes and isolation
>>>>>> transformers on the test bench!
>>>>>>
>>>>>> https://www.youtube.com/watch?v=XBsQ3sZ45Fk&feature=youtu.be
>>>>>>
>>>>>> https://www.youtube.com/watch?v=xaELqAo4kkQ
>>>>>>
>>>>>>
>>>>>> On 11/3/2018 12:36 PM, Mick [email protected] [EVGRAY] wrote:
>>>>>>>
>>>>>>> Norm,
>>>>>>>
>>>>>>> Thanks for the nudge in the right direction. Now the process
>>>>>>> demands repeating with a totally isolated battery source
>>>>>>> configured the same way. Funny how I was concentrating on
>>>>>>> isolating and connecting saturated inductive charge without the
>>>>>>> first magnetic variable taken into account.
>>>>>>>
>>>>>>> I have had no problem creating the event with my grid power
>>>>>>> source and even warned Sven that an isolation transformer will
>>>>>>> not always protect his scope when messing around with this
>>>>>>> energy. My scope probe sitting on a bench shot me in the leg
>>>>>>> when I walked by when performing the experiments from my bench
>>>>>>> supply. The bench supply has an isolation transformer of sorts.
>>>>>>> Being it is torroidal there is more inter-winding capacitive
>>>>>>> coupling and mutual inductance than with the proper EI
>>>>>>> transformer though there is at least the electrostatic shield
>>>>>>> and galvanic isolation.
>>>>>>>
>>>>>>> Thanks for that reference. the Brit guy was funny, although I'm
>>>>>>> very familiar with iso transformers in audio work used for
>>>>>>> galvanic isolation and balancing to eliminate common mode noise.
>>>>>>>
>>>>>>>
>>>>>>> On 11/3/2018 4:42 AM, Norman Wootan [email protected] [EVGRAY] wrote:
>>>>>>>>
>>>>>>>> Mick! Your DUH reference is funny! To understand
>>>>>>>> Isolation, best to study and understand the Isolation
>>>>>>>> Transformer. The super high quality ones are built to
>>>>>>>> eliminate noise and DC components that effect sensitive
>>>>>>>> instruments like EEG and EKG instruments. This will give you an
>>>>>>>> idea as to construction and purpose::
>>>>>>>>
>>>>>>>> https://en.m.wikipedia.org/wiki/Isolation_transformer
>>>>>>>>
>>>>>>>> A little tutorial as to how they work!
>>>>>>>>
>>>>>>>> https://www.youtube.com/watch?v=sfzy5IQMzyc&feature=youtu.be
>>>>>>>>
>>>>>>>> https://www.youtube.com/watch?v=14kPQif9P7c&feature=youtu.be
>>>>>>>>
>>>>>>>> https://toroid.com/Products/Medical-Isolation-Transformers
>>>>>>>>
>>>>>>>> The 230VAC, 5 HP locked rotor experiment was an example of
>>>>>>>> electrically isolated electrical circuitry when mains contactor
>>>>>>>> was opened since there was no neutral involve. There is
>>>>>>>> magnetic and capacitive coup[ling only The dielectric
>>>>>>>> insulation was not compromised therefore no electrical
>>>>>>>> connection. The Chinese motor experiment was isolated,
>>>>>>>> (electrically) when the reversing action was in transient.
>>>>>>>> (Floating neutral) since there is a line neutral in the 120VAC
>>>>>>>> input.
>>>>>>>>
>>>>>>>>
>>>>>>>> On 11/2/2018 2:44 PM, Mick [email protected] [EVGRAY] wrote:
>>>>>>>>>
>>>>>>>>> Norm,
>>>>>>>>>
>>>>>>>>> Since you have performed mass research on this event would you
>>>>>>>>> concur
>>>>>>>>> with my long distance observation that the event is not only
>>>>>>>>> due to
>>>>>>>>> charge isolation but inclusive of a magnetic connection from
>>>>>>>>> source in
>>>>>>>>> addition to the saturated and lifted inductive load?
>>>>>>>>>
>>>>>>>>> Your bell buzzer and bell transformer acting as an isolation
>>>>>>>>> transformer.
>>>>>>>>>
>>>>>>>>> Both motor experiments, the small Emerson type and the HVAC
>>>>>>>>> unit with
>>>>>>>>> only two hot's no neutral, must have been powered by an isolation
>>>>>>>>> transformer of some type also such as the utility step down
>>>>>>>>> for the
>>>>>>>>> neighborhood or dedicated delta or wye for commercial or even
>>>>>>>>> acted as
>>>>>>>>> such from the dual windings of the HVAC motor.
>>>>>>>>>
>>>>>>>>> Have you reliably produced the NS from any type of isolated
>>>>>>>>> battery
>>>>>>>>> system, or in all such cases was there a magnetic connection
>>>>>>>>> to an earth
>>>>>>>>> bonding in another spot?
>>>>>>>>>
>>>>>>>>> My thoughts being one side of a transformer acting as a source is
>>>>>>>>> grounded and the secondary side isolated so that the only
>>>>>>>>> conceivable
>>>>>>>>> ground bonding on the sink might be considered as magnetic
>>>>>>>>> aside from
>>>>>>>>> the bonded motor frame or what not producing the reconnection.
>>>>>>>>>
>>>>>>>>> I may be pissing up a rope notwithstanding the NS seems to be
>>>>>>>>> predicated
>>>>>>>>> on a B field connection somewhere in the source feed though
>>>>>>>>> the neutral
>>>>>>>>> is isolated electrically.
>>>>>>>>>
>>>>>>>>> Perhaps this is a simple "Duh" to you that you had already
>>>>>>>>> figured out
>>>>>>>>> assuming everyone else at least this smart. Either way it
>>>>>>>>> does create
>>>>>>>>> an interesting position in which to view 3 phase and
>>>>>>>>> transformers with
>>>>>>>>> an extra resonant winding.
>>>>>>>>>
>>>>>>>>> By the way, ironic your implication that the large medical
>>>>>>>>> isolation
>>>>>>>>> transformers create a heretofore unknown vector of extreme danger.
>>>>>>>>>
>>>>>>>>> Mick
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
>