Electric safety in baptismal pools

Removing the potential for electrocution

Never, ever, use a wired microphone in a baptismal pool. A recent case [www.cbsnews.com/stories/2005/10/31/national/main995829.shtml] in Texas is only the latest of a long series of tragedies around the world, with church leaders being electrocuted in pools. Even a normally harmless leakage of stray volts into a microphone is lethal when a person is immersed in water.

Make it your church policy that there is no mains-wired electrical equipment of any sort within arm’s reach of a baptistry pool, and that a permanent warning is displayed on your PA equipment about this. Your policy should include:

• no wired microphone (i.e. connected by a lead to an amplifier) to be used in, or within 2 meters of a pool (not even someone outside the pool holding a long boom towards the pool – it could fall in.
• no other electric audio-visual equipment: camcorders, tape recorders, guitar, etc., connected to mains power even through a low voltage transformer, to be used within 2 meters of a pool.
• no light fitting or electric socket to be located within 2 meters of a pool.
• permanent warning notice of this policy to be displayed near the PA equipment.
• if you have any permanent electric or microphone sockets within 2 meters of the pool, particularly power sockets set into the floor, they could easily be splashed and make the entire wet area live. Consult a qualified electrician about either totally isolating these circuits with remote double-pole switches, or covering them with temporary totally-waterproof sealing boxes.
• underwater lighting for a baptism pool is also inherently risky, and was implicated in one recent fatality. It seems ridiculously un-necessary anyway.
• all electronic (and other) equipment should in any case be earthed. Audio users sometimes disconnect the earth lead, to try to reduce audible mains hum. The integrity of earth connections within equipment, and the earthing circuit within the building, should be checked by a qualified electrician using a meter.
• despite these precautions, if any item of electrical equipment should fall into a pool, occupants of the pool should freeze, the item be unplugged (not just switched off) and confirmed to be unplugged (there may be many cords plugged in to a multi-socket box) and removed from the water by a dry person from outside the pool.

Please DO NOT believe that an earth leakage (residual current) trip-switch (RCD) can give sufficient safety – it cannot in these circumstances. Whatever claims you may read that they are sufficient to achieve pool safety, it is just not possible. While in normal (dry) circumstances, RCDs are a vital safety requirement in any public building, they cannot protect someone in a baptismal pool because:

• a vastly lower voltage and current is fatal when immersed in water. (Note that heart pacemakers control heart-beat using a low voltage battery and incredibly low current output.)
• trip switches only cut out when there is an imbalance in current in the mains feed to the equipment. They will not detect current drawn from a secondary circuit within electronic equipment.

A very low electric current of a few milliamps kills instantly in this situation. Stick the permanent warning message on your sound mixer or amplifer: Behind the Mixer [www.behindthemixer.com/article-waterproof-microphone.php] offers an article on the subject, explaining safe alternatives, with a free notice ready to download and print – do it today.

These recommendations also apply when using a mobile power source in an outdoor baptismal location.

Safety for musicians

You should also institute safety procedures for musicians using instruments connected to amplifiers. Electrocutions of guitar users are common. A sweaty hand touching metal guitar strings, with the other hand touching a microphone, can create a lethal path for electric current via the heart. This can occur due to instruments being incorrectly wired, or not earthed, or touching a faulty microphone while holding a correctly earthed guitar, or power from a faulty amplifier coming back up the guitar earth connection. Musicians are often tempted to disconnect earth connections in amplifiers or guitars, in order to prevent earth loop problems causing mains hum. And if they are playing in an away venue, they have no way of knowing if there is earth continuity in their power supply. Safety policy should include:

• Never disconnect earthing connections. (Good technical solutions are available to remove hum. Pay for them.)
• Have all equipment and power extensions regularly checked using a multi-meter.
• Fit RCD trip-switch plugs (30 milliamp, or even 10 milliamp if you can obtain them) to all amplifiers and lighting equipment.
• Additional safety (protective resistance/capacitance circuits) can be build into a guitar itself to prevent a lethal current reaching the strings (including power coming back up the earth wire from faulty wiring in the amplifier or mains connection): this procedure is frequently explained in guitar magazines.

Links:
• Safety seminar PowerPoint
• RCDs explained

Disclaimer: you should always take professional advice, and also ensure that your installation and practice complies with (and probably exceeds) local regulations in your country.