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AQUARIUM ELECTRICAL SAFETY
By Mike Owen
First published in Tank Talk, Canberra and District Aquarium Society, Australia
Safety around the aquarium, electrical safety in particular, is a subject all aquarists should be
concerned about. The possible fatal consequences of the combination of water and faulty
electrical equipment is something we all should bear in mind. One of the basic rules of
aquarium management that I have seen in several aquarium books is to turn off all electrical
power to the aquarium before putting your hand in -the water. However, hands up all those
who have ignored this rule; I bet there are not too many hands still down.
The amount of current needed to give a person an electric shock is surprisingly low. With a 240
volt supply, a current of only 10 milliamps through your body to earth can give a painful shock,
and a current above 50 milliamps is likely to be fatal. Not very much when a 200 watt beater
draws something like 800 milliamps. While the possibility of a dangerous failure in modern
commercial aquarium equipment is very, very slight, nevertheless a risk still exists. I've never
seen any report of a person being killed by a shock from their aquarium in Australia but I have
seen a report in an English newspaper of this happening, and have vague recollections of
reading that several people die each year in the U.S.A. by electric shocks from their aquariums.
If your aquarium equipment is plugged into a normal household switchboard, with standard
circuit breakers, it is highly unlikely that they will cut-out in the event of a fault in the
equipment leading to a possible leak to earth of the low magnitude needed to cause a bad
shock. Fortunately there is a simple, but unfortunately fairly expensive, safety measure which
can be taken. This is to install a CORE BALANCE EARTH LEAKAGE CIRCUIT BREAKER, or ELCB for
short, into the wiring system for your aquariums.
These devices work by continually monitoring the current in both the active and neutral wires
of the circuit, and if a fault develops in the circuits leading to the leakage of current to earth,
then the device instantaneously breaks the circuit. They are set to break the circuit only above a
certain current loss, since some home appliances such as water heaters and freezers naturally
have small current losses. The cut-off level ranges from 10 milliamps to 30 milliamps, with 30
milliamps being suitable for the aquarium.
Three types of ELCB are available. The first is wired into the main switchboard of a house and
can give protection to all power points in the house, not just the aquarium power point. I'm not
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