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GFCI WHY?
A Ground Fault Circuit Interrupter (GFCI) is a device designed to protect against electric shock. The GFCI operates by sensing the difference between the currents in the Hot and Neutral conductors. Under normal conditions, these should be equal. If a person should come in contact with the live (HOT) wire and a path to ground, current would begin to flow through the body and therefore create in imbalance with the Neutral conductors current. The GFCI senses this imbalance (uneven current) and trips, cutting off power to the load side of the GFCI and protecting the person from shock.
An aquarium is the perfect place for a GFCI. Imagine a heater or submersible pump that has allowed water to leak into the electrical components. The Hot wire is now exposed to the tank water. When you place your hand in the water you are in essence touching the hot wire. If any other part of your body is in contact with a grounded object (reflectors, equipment, concrete floors, etc), current will begin to flow through your body! This can easily be a deadly situation and why a GFCI is an essential piece of equipment. A grounding probe added to the system can enhance the level of protection offered by a GFCI, this will be discussed in the grounding probe section of this article.
It is very important to understand that a GFCI does NOT protect against ungrounded shocks! That is, if a person contacts the HOT and NEUTRAL conductors, the current will flow through the body but still show as balanced to the GFCI. In this scenario, the body has become part of the load!
Many reefers incorporate a single GFCI into their setups and then plug all of their equipment into it. In a similar fashion, some reefers replace the standard circuit breaker in the service panel with a GFCI circuit breaker.
A single faulting piece of equipment (or a nuisance trip) will result in loss of power to all of the equipment connected to the GFCI (or circuit in the case of a GFCI breaker). Both GFCI receptacles and GFCI circuit breakers are also susceptible to nuisance tripping. Ballast and motor loads create a complex signature that sometimes confuses GFCIs into thinking a fault has occurred.
It is a good idea to separate important equipment among multiple GFCIs. In doing so, a single faulting piece of equipment (or nuisance trip) will only result in an isolated outage instead of a tank wide shutdown. You CAN NOT daisy chain GFCI receptacles by connecting a GFCI in series with the LOAD terminals of another GFCI. They will not operate as expected and will certainly cause problems. However, you can safely wire GFCI receptacles in parallel! Parallel GFCI receptacles will operate as expected when wired in parallel. Click on the schematic drawing to the left to see an example. The drawing depicts three GFCI receptacles wired in parallel. The 3rd unit has a standard (slave) receptacle wired to its load terminals. The standard receptacle is protected by GFCI #3. Slave receptacles (also know as downstream receptacles) can be added to any of the GFCI units and multiple GFCI units can be paralleled. The use of a ground probe is recommended and will be covered later in this article. Protect yourself and your family, implement GFCI protection on your tank!
AFCI WHY NOT?
Arc Fault Circuit Interrupters are designed to detect the electrical signature caused by electricity arcing someplace in the circuit. If arcing is detected, the AFCI breaker trips and removes power from the circuit. At first glance the AFCI appears to be a perfect candidate for fish tanks. Where there is water and electricity, there is a significant chance of arcing type fires. The problem is that AFCI breakers have a well deserved bad reputation for nuisance tripping when posed with a complex load such as a motor or ballast. An AFCI would add significant safety to a fish tank setup, but would also expose the livestock to a much higher greater risk of nuisance induced power outages. Most AFCI breakers also incorporate a GFCI into the device. A single GFCI used to power your tank (as mentioned above) is not a good idea. If you do not use AFCI circuit breakers (or the newer AFCI receptacles) then please take the precautions to prevent arcing type fires. That means taking precautions to protect power strips and other devices that will be exposed to moisture, drips and salt creep.
