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Electricity And Electrical Safety Basics For The Aquarium Hobbyist


With the recent entries in the ARC Forums concerning various electrical and equipment malfunctions that could have resulted in very tragic endings, I felt there was a need to address this issue. As this title states this FAQ entry will briefly cover the very basics of the subject matter. It is hoped that future entries will go into more detail. I will cover the basic definition of electricity, wiring requirements and wiring hazards, and safety precautions and preventions.

Electricity is the flow of electrons through simple materials and devices. There are two states of electricity- it is either DC (direct current) or AC (alternating current) and while it is the AC state that will be addressed in more detail, both could prove deadly. The rate of an atoms electron flow in an electrical circuit is called amperage and the measurement is in amperes. An ampere is the amount of current that will flow through one ohm (resistance) under a pressure of one volt. The mathematical formula is I=E/R, where I is the current, E the voltage and R the resistance. Another term I will be using is the watt (W), which is the power that a device or devices uses to do the work. One result of this work is heat.

At this point I will bring up the fact that under unfavorable conditions only 100 milliamps (.001) of current can kill a person. This is why care must be used when working around electricity. This will be discussed later in detail. However, if you do not know what you are doing or unsure it is wise to contact a qualified electrician.

For us the ac voltage of households is constant at 120v (although it is possible that some use 240v). In looking at the above formula it can be seen that with a constant voltage it is the resistance of a material that affects the current flow. In Attachment 1, is the Element Periodic Table, providing a visual listing of the elements' electrons. As stated it is the number of electrons that establishes a materials conductivity of current. Plastic or acrylic, glass, wood and even air are non-conductors, meaning there are no free electrons and therefore there is no current to flow through the material resulting in high resistance. However the adage of "water and electricity don't mix" holds true due to the minerals and elements contained in water. Under perfect conditions RO/DI water has a higher resistance then the salt water we use. We of course compound this by adding more trace elements to the salt water.

Below is a paragraph taken from the article "Composition of Several Synthetic Seawater Mixes" by Marlin Atkinson and Craig Bingman, and published by Aquarium Frontiers and Fancy Publications, Inc., as found in ARC FAQ "Chemistry 101" entered by Dapettit. The paragraph cited provides the general elemental makeup of Ocean Saltwater:

"The salinity of near-surface seawater in the tropics is approximately 35 parts per thousand (ppt), so 35 gram samples were dissolved in highly purified water, brought to one liter and analyzed. The elements sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), strontium (Sr) and boron (B) were determined with a Perkin Elmer Atomic Absorption Spectrometer. The anions chloride (Cl-) and sulfate (SO42-) were determined by ion chromatography, which would also detect Br- and F- if present. The concentrations of lithium (Li), silicon (Si), molybdenum (Mo), barium (Ba), vanadium (V), nickel (Ni), chromium (Cr), aluminum (Al), copper (Cu), zinc (Zn), manganese (Mn), iron (Fe), cadmium (Cd), lead (Pb), cobalt (Co), silver (Ag) and titanium (Ti) were measured by Inductively Coupled Plasma (ICP) spectroscopy.

Notice the number of the elements in sea water that are used in the electronic and/ or electrical fields. This is mainly due to their ability to conduct electricity as seen by the number of electrons each contains. For example, copper (Cu) which is used in almost all electrical house wiring and circuit board conductors have an electron count of 27. Silver (Ag) and lead (Pb) which make up the high end solder used to attach components to the circuit boards has electrons of 37 and 54 respectively. Integrated Circuits are formed/made/grown from lithium (Li), Silicon (Si), or Barium (Ba) and have 3, 14, and 29 electrons respectively. Even two of the recommended trace elements for coral – Manganese (Mn) and Strontium (Sr) with electron counts of 23 and 28.

I have included a chart the end of this FAQ (see Attachment 2) titled "Abundance of Elements in the Earth's Crust and in the Sea" and a listing of elements by atomic number (see Attachment 3) to supplement both the above paragraphs and the Element Periodic Chart in Attachment 1. All three Attachments were obtained from the "Handbook of Chemistry and Physics" 77th Ed., by David R, Lide (Editor) and published by CRC Press in 1996.

Explanation of household and Aquarium wiring:

Maximum current is limited by the safety devices being used, be they circuit breakers in the main incoming power distribution panel and/or fuse or circuit breaker of the device(s) being used- be it a power strip or ballast for example. The formula for wattage is: W=I x E. Using the formula and entering constants of voltage and a 15 amp circuit breaker = W=15 x 120 = 1500 watts total available for that circuit. I want to make it clear that each device plugged into that circuit branch adds to the total wattage being used and heat being dissipated.

Overloading the maximum capability of a circuit branch could result in heat damage to the devices and/or electrical wiring and in worse case result in a fire.

Probably a majority of us use an already installed wall outlet that is available in the room where the tank is located and using multiple outlet power strips to plug in their various pumps, heaters, lights, etc. Now let's take a look at the total wattage being used for an average mid-size (55 gal for example) aquarium: (note: all wattage figures taken from the latest F&S Aquatics Catalog) Lights 48" 4 T-5 lamps (Nova Extreme SLR) 216w or going with a 48" 150w halide and T-5 combination (Aqualight Pro HQ1/Compact Fluor/Lunar Light) 492w. Four each Koralia 4 pumps 48w, one Eheim #1260 water pump 65w, and heater 200w. We can see that the basic power used for a simple set-up is either 529w or 805w and well within the 1500w available or so it appears.

The voltage for the 15amp outlet used for the tank comes from the master power distribution panel circuit breaker. Besides the tank outlet the wiring is usually daisy chained to every other outlet and/or switch located in the room. This is referred to as a circuit branch. Each device plugged into an outlet or through the switch and turned on adds to the total load being used in that branch.

Now let's look at wiring diagram for a room (for example the living room's circuit branch) where the tank is located. There could be 6 or 8 outlets throughout the room plus 2 or 3 wall switches. Devices plugged into the outlets/switches could be two 60w table lamps, an overhead fan with the fan motor drawing 80w, the fan light fixture of only three (3) 40w bulbs 120w, porch light 60w, and in the room would probably be a TV, Stereo, or even a computer system (will be generous and figure these entertainment items use only a combined 400w). We now have the additional potential of adding 780w to the circuit. If we add the tank's input the maximum wattage load could be either 1309w or 1585w. We might get by with just the T5s, but the halide combination would overload the circuit. Hopefully at this point the circuit breaker will trip.

At this point I want to go into more detail and explanation concerning the dangers/hazards we have in the hobby. I will be taking direct quotes from the book "Electrical Wiring Residential 13th Edition" by Ray C. Mullin and published by Delmar Publishers and based on the 1999 National Electrical Code.

"Many injuries have occurred and many lives have been lost because of electrical shock. Coming in contact with live wires or with appliance or other equipment that is 'hot' spells danger. Problems arise in equipment when there is a breakdown of insulation because of wear and tear, defective construction, or misuse of equipment. Insulation failure can result when the 'hot' ungrounded conductor in the appliance comes in contact with the metal frame of the appliance. If the equipment is not properly grounded, the potential for an electrical shock is present."

"The shock hazard exists whenever the user can touch both the defective equipment and grounded surfaces, such as water pipes, stainless steel sinks, metal faucets, grounded metal lighting fixtures, earth, concrete in contact with the earth, water, or any other grounded surface."

"A severe shock can cause considerable more damage to the human body than is visible. A person may suffer internal hemorrhages, destruction of tissues, nerves, and muscles. Further injuries can result from a fall, cuts, burns, or broken bones."

The chart below shows the effects that various DC and AC current levels can have on the Body:



Men Women Men Women

Slight sensation felt at hand(s) 1.0 mA 0.6 mA 0.4 mA 0.3 mA


Threshold of Perception 5.2 mA 3.5 mA 1.1 mA 0.7 mA


Painful, but voluntary muscle

control maintained 62 mA 41 mA 9 mA 6 mA


Painful, no muscle control,

unable to let go of wires 76 mA 51 mA 16 mA 10.5 mA


Severe pain, difficulty breathing 90 mA 60 mA 23 mA 15 mA


Possible heart fibrillation after 1 second 500 mA 500 mA 200 mA 200 mA


Possible heart fibrillation and Death

after 3 seconds 500 mA 500 mA 100 mA 100 mA


Heart Failure -* -* 500 mA 500 mA


note: -* = unable to locate readings for heart failure levels for DC current.

Continuing quoting from the "Electrical Wiring Residential:

"The effect of an electric current passing through a human body is determined by 'how much current is flowing and the length of time the current will flow'. Experts say that the resistance of the human body varies from a few hundred ohms to many thousand ohms, but generally agree on values of 800 to 1000 ohms as typical. Body internal resistance, body contact resistance, moisture, duration, voltage, as well as path of current: finger to finger, hand to hand, hand holding 'hot' wire, hand holding metal or metal tools, hand or arm in water, standing in water, hand to foot, foot to foot, etc. all have an effect on the severity of the shock".

Of course the worse case for any of the above is that the body contact causes the current path to flow through the heart.

The use of fuses and/or circuit breakers in the electrical devices and circuits are to mainly protect those same devices and circuits from current overloads. And though they also protect somewhat against short circuits, due to the resistance of the human body they may not react in time to prevent injury or death in the case of electrocution. We have all heard, read, or seen on TV Dramas, the cases of people dying from a hair dryer or radio falling into the tub while they are taking a bath. Reaching into or working in a saltwater tank with a defective device would amount to the same thing. To prevent this, the National Electrical Code calls for the use of Ground-Fault Circuit Interrupter devices (GFCI) as follows:

"The code states that personnel ground-fault protection be provided for all 125 volt, 15 and 20 amp receptacle outlets in dwellings as follows: In bathrooms, outdoors, in kitchens (for all receptacles that serve the countertop), within six feet from edge of wet bar sink, and for spas and swimming pools."

Although the code also calls for use of the GFCI in other areas, I only mention those above due to all being water or moisture related.

There are three types of GFCI available for use by the home owner: the Receptacle, Circuit Breaker, and Portable.

1. The Receptacle Type: This type of GFCI is used in place of the standard duplex outlet found throughout the house. It fits into the standard outlet box and protects against "ground faults" whenever an electrical device is plugged into the outlet. Most receptacle-type GFCIs can be installed so that they also protect other electrical outlets further "downstream" in the branch circuit.

2. The Circuit Breaker Type: In homes equipped with circuit breakers rather than fuses, a circuit breaker GFCI may be installed in a panel box to give protection to the entire circuit branch. It serves a dual purpose- not only will it shut off electricity in the event of a ground-fault, but it will also trip when a short circuit or an overload occurs. The protection covers each outlet, lighting fixture, heater, etc. served by the branch circuit protected by the GFCI in the panel box.

3. Portable Type: Where permanent GFCIs are not practical, portable GFCIs may be used. One type contains the GFCI circuitry in a plastic enclosure with plug blades in the back and receptacle slots in the front. It can be plugged into an outlet, then the electrical devices, equipment is plugged into the GFCI. Another type of portable GFCI is an extension cord or power outlet strip with a GFCI. It adds flexibility in using multiple receptacles that are not protected by GFCIs.

NOTE: For the hobbyist the Portable Type is probably the easiest and cheapest way to go - as long as the total load is kept safely below the maximum established by the circuit branch. However, I consider this as a temporary measure as it is very easy for the hobbyist to upgrade or add additional equipment over time without further addressing the max load issues.

The GFCI works by monitoring the current balance between the ungrounded 'hot' conductor and the grounded 'neutral' conductor. As soon as the current flowing through the 'hot' conductor is in the range of 4 to 6 milliamperes (mA) or more than the current flowing in the 'return' grounded conductor, the GFCI senses this unbalance and trips (opens) the circuit off. The unbalance indicates that part of the current flowing in the circuit is being diverted to some path other than the normal return path along the grounded return conductor. If the 'other' path is through a human body, the outcome could be fatal. However in referring to the chart above it can be seen that this trip current is well below the danger level. A shock might be felt initially, but any possible dangers or injuries will be avoided.

A GFCI provides ground fault protection only. It does not provide overload protection for the branch circuit wiring unless it is the circuit breaker type installed in place of the circuit breaker in the main power distribution panel.

There are other electrical devices available which provide protection for the homeowner such as surge protectors, IDCIs (Immersion Detection Circuit Interrupters – usually installed in devices themselves), AFCI (Arc-Fault Circuit Interrupters – to prevent fires caused by electrical arcing), and Lightning Arresters. Further discussion of these various protection devices is outside the scope of this basic article but may be addressed later.

In closing, I want to discuss what can be done to keep the hobby safe and enjoyable by the aquarium owner.

1. It is highly recommended that as soon as possible an electrical inspection/survey be taken for the aquarium room. First point is to identify the circuit breaker (or fuse for older homes) at the power distribution panel that controls the outlets/switches for the room, the size of the breaker (usually marked on the breaker switch-10, 15, 20, etc), and the type (standard on/off or GFCI {Ground Fault Circuit Interrupter).

The second need is to identify and calculate the loads of the various devices normally plugged into the outlets or controlled by the wall switches. You should also figure in devices that could be temporary plugged into outlets (i.e. vacuum cleaner). The next step should focus on the aquarium outlet(s) and the various devices and loads in use at the time of the inspection. It would also be a good idea to figure out loads for any future equipment to be added.

Finally total up the maximum load that could be used should all devices be turned on. If it is near or close to the limitation of the circuit breaker size, then it is time to contact an electrician and discuss the addition of a new dedicated circuit for the aquarium. By this I mean a running of new electrical wiring from an unused circuit breaker in the power distribution panel and installing a new outlet for use by the tank equipment only. My recommendation for this aquarium only branch circuit would be a 20 amp circuit through a GFCI breaker or two 15 amp GFCI protected circuits. Note: 20 amp circuit branches requires using size 12 AWG (American Wire Gauge) copper wire and a 15 amp – 14 AWG copper wire.

2. Establish a scheduled routine to check all equipment being used. Turn off the devices and unplug them. Check the item for wear and tear. Check the operation of on/off switches, circuit breakers, and ensure the fuses (if installed) are the correct type and size. Never over fuse a device for any reason, not even as a temporary measure. Check its power cord condition – both at the socket end and where it enters the item. If either the device or cord appears questionable – replace it as it is better to be safe than sorry.

3. Saltwater is highly corrosive – inspect all electrical outlets, plugs, etc. for oxidation or corrosion. Again if there are any questionable conditions- replace it or contact an electrician to further check the wiring and if he feels it is necessary, replace the outlets. One further note: never replace just the plug; the electrical cord should be one unit, i.e. molded plug.

4. Try to avoid using cheap extension cords. Use only those who current carrying rating is equal to or greater than that of the circuit branch (see item 1. above). Again go only with those that are GFCI protected.

5. Never work around an aquarium when there are lightning storm warnings for the area. This also goes for using any electrical devices. Again Safety first.

6. Use 'drip loops' for all electrical cords plugged into outlets or power strips. This will keep water from running down the cord and shorting out the outlet.

7. Finally read and heed the "Safety" Instructions and Warnings found in the instruction sheet or manual that comes with all equipment. Federal Regulations set forth in OSHA (Occupational Safety and Health Act) requires manufacturers to ensure that users of the items are informed of all possible hazards.

8. Keep on hand an electrical 'safety kit'. In a dry, but readily accessible location have available as a minimum: a multimeter, a six foot plus length of dry rope (or other similar non-conductive material), and rubber gloves (preferably shoulder length). While the multimeter and rubber gloves usage should be self explanatory, the purpose of the rope is to provide a second party a means to pull you away from the shock hazard without coming in contact with you or with the hazard themselves. Remember: what could initially be a non-life threatening shock to you could prove deadly to both you and the person who touches you if they provide a more serious current path to ground.

9. Clean up all water spills immediately.

10. Ensure all household members know the dangers that exist, as well as the locations of the switches and/or circuit breakers controlling the branch circuit(s) of the aquarium in case of emergencies.

Finally have fun, enjoy the hobby, but be safe, but I want to again repeat: when working around electricity if you do not know what you are doing or unsure it is wise to contact a qualified electrician





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