Electrocuted by microphone? yes is possible
If the whole sound system is assembled properly and according to the manufacturers, then no.
If I remember the course on this subject, most 48 volt power supplies are actually around 18
volts or less for one mic. Then as more mics that need power, the voltage increases due to the
impedance load change. The current they put out is about the same as a 3 volt battery.
The way most phantom power supplies are designed in a mixer, when there is a short of pin 1
or any other serious problem, the circuit either self limits or fails. All the wires for the phantom
power are not large enough to carry anything more that a fraction of an amp. If 120 AC current were
to show up on the Phantom power leg, the wire would most likely melt, create an open circuit and
most likely trip the fuse or circuit breaker on the AC side of the mixer.
In 1979 a minister in Niagara Falls Canada was killed in a similar way. The church used a portable
powered mixer. They lifted ground on the mixer because of RF problems. They also soldered all of
their mic cable ground wires to the barrel of the XLR cables at both ends to get rid of the RF problem
as well. The made a small wire connection from pin 1 to the lug on the screw connector that secures
the mic connector to the barrel. This provide a great path for AC to travel down a mic cable. In this
church they did this to the installed cables and the hand held cables. I know you may likely ask where
was the CSA report about it. In the CSA report, the power supply in the mixer was defective. An AC wire
that was twisted together and then bent around a corner in the power supply was not properly crimped.
Over time the connection slipped out of the un-crimped connector and was dumping AC to chaise.
Posted: at 10-12-2012 04:23 PM (10 years ago) | Newbie |
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