haysanatar; Glad you're still with us. That was a close one.
Let's get to it!
For starters there was no electrocution unless someone had to resuscitate you. You got shocked. Badly shocked it sounds like but "shocked".
For general knowledge I will run down the proper troubleshooting method for this too common system ailment.
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Troubleshooting your shocking tank.
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You need a voltmeter capable of measuring your house/system's actual voltage.
In the USA that will be 120V AC.
Fundamentally the method of troubleshooting a shocking tank is to replace the shocked human with a voltmeter to provide a safe and definitive indication of the problem and a way to to prove subsequent correction.
Before I can continue to discuss this I need to state that if you are at all concerned with your ability to do this, you should NOT do it, but should get someone experienced to help you on location.
Theory.
In all domestic power systems there are three circuits.
One is generally called the "HOT". This is essentially the "source" power.
One is called the "RETURN" or "neutral" and is the designated path of power return to the utility.
One is called "GROUND" or "earth" an alternative return path used only for safety.
In a perfect system all power arrives on the HOT and returns on the RETURN.
The GROUND is required in the USA to always be hooked or 'bonded' to the NEUTRAL or RETURN at the dwelling power panel and only at the dwelling power panel.
This means that any appliance could actually be powered by using the HOT and the GROUND and it would perform identically. This would be a very bad thing to do and is actually illegal as the safety a ground could provide would be compromised if this was done. The reason I point this out is to point out that the ground is a perfectly good return as far as the HOT is concerned.
Where is the ground? As far as you are concerned it's everywhere. The wood you stand on, the dirt your house is sitting on, the concrete your floor is made of, the Linoleum, the carpet, tile. In short anything that can conduct even tiny amounts of electricity and is ultimately tied to dirt somewhere. What would not be GROUND would be that dry glass or acrylic you're standing on or dry plastic.
What is happening when you get shocked is you are being connected to the HOT due to a mechanical failure while being also connected to the GROUND. You do not always die through electrocution because the complete circuit through your body includes your skin resistance and other resistances in either the HOT part of the circuit or the ground part of the circuit. Perhaps your carpet, the pad under it, the wood below that, have enough resistance to limit the current to below fatal amounts. This is why you need to be careful troubleshooting a problem because if the shoes, and floor are the only thing limiting the current through you, to below fatal levels, you could touch something like your light fixture that's solidly grounded and suddenly have a fatal current flow. This why messing about trying to fix a shocking tank can be so dangerous. In the process you could lower the resistance and.... find yourself.. pushing up daisies.
Back to my original point; that we want to replace you with a voltmeter. Here in lies the one difficulty. You can't just throw one of your voltmeter leads on the floor and call that GROUND. That ground connection is complex through your feet/shoes/sweat/etc. We need a solid ground to hook our GROUND probe of our voltmeter to. This is actually the hardest part of troubleshooting our shocking tank.
The first thing we must do is find a reliable ground for our ground reference. How to do this.. In most homes now in the USA our outlets are grounded outlets. They have three prongs. Again, one is the HOT, one is the RETURN, and one is the GROUND.
We will cover the lack of a GROUNDed outlet in the troubleshooting below.
Here we go:
1) We need to prepare the meter. Set your meter to a setting that will not be exceeded by measuring your power and doesn't exceed the meter's ratings. You need a setting that exceeds 120VAC in the USA. It can be 200V, or 400V, or whatever. Make sure you select AC volts as your meters will also do DC and since we are only looking at AC will read zero all the time if set to DC, possibly leading you into a dangerous situation. Also make sure the leads are in the correct holes of the meter to measure AC volts NOT AMPS. If you accidentally leave the leads in the A or mA holes your meter will either blow an internal fuse, blow the internal measurement resistor, or explode in your hand. You don't want that to happen..
2) We need to prove the meter is working. Go to a receptacle and stick one probe in one hole and the other probe in another hole. You should see your country's domestic power voltage displayed. If you don't, review your meter settings, then rearrange the probes to every possible combination in the receptacle holes until you do see the correct voltage(~120V there is no more 110V in the US. Don't be archaic by calling something '110'). Once you see the voltage wiggle your lead wires to prove your test leads/probe aren't flaky. This is important because they often are flaky and, as stated, you don't want a flaky meter misleading you in this life-safety exercise.
3) OK, we've proven your meter is doing its job. Now we need to find a GROUND. Go to your aquarium outlet. We need to troubleshoot the actual aquarium outlet because it could be miswired. With USA three prong outlets we do this by holding one probe in one slot and trying the other probe in the remaining two slots. The one slot that gives the country voltage when the other probe is in, either of the other two slots, is the HOT. Note which it is. In the USA the narrow slot shall be the HOT, the wide slot shall be the RETURN or NEUTRAL, and the middle funky slot shall be the ground. So our above test should confirm that the meter probe in the narrow slot and the other in either remaining slot should give the desired country voltage reading.
Note: The USA voltage could be 115VAC clear to 130VAC. Do not concern yourself with this variation.
4) SPECIAL CASE: If we have no official ground because we have only two prong outlets, then we need to find an unofficial ground! How? This is where we need some ingenuity. If you're in a USA house and you have a grounded outlet somewhere else you can use it. Perhaps an outdoors outlet, or one in the garage, or one in the kitchen, or bathroom. Use a grounded extension cord. Plug it into the grounded outlet and bring the receptacle end over to your tank outlet. (In the USA make sure your meter is set to at least twice your country power before proceeding.) Proceed with "finding the HOT" routine above with ONLY the extension cord outlet. Locate the HOT. If both the other holes work to complete the circuit you can assume the normal center one is ground. You will then use this ground for further testing at your tank outlet.
If you have no other grounded, three prong, properly installed outlets in your abode then we need to get draconian on finding a ground.
Move around your house with your meter. Find something metallic like a water pipe, or a steel gas pipe, or a faucet, or the metal screw holding your outlet covers on. Stick one lead on the candidate and the other into into nearby outlet slots. See if you read your country voltage. Do this until you are successful in finding an unofficial GROUND.
Once you have located a GROUND you need to conduct it over to your tank outlet. Get some wire of any kind. Strip the insulation off the end. Tape the wire to your new found GROUND. Run the other end over by your tank outlet. Now, using your meter, run the "find the HOT" test to prove you have a HOT, RETURN, and this new temporary GROUND.
Tape one of your leads to the ground lead, or get someone to hold the meter test probe into the GROUNDED outlet's confirmed ground hole. If someone is just holding it they have to be diligent at it as it's easy to have your little probe tip miss the actual ground conductor inside the receptacle. If your outlet is grounded, often, the screw holding the plate on is also and can be a better place to actually hold the ground probe. You can also loosen that screw and temporarily wrap a wire around it and tighten it back up. Tape the other end of the wire to the GROUND meter probe for hands free work.
Whew! Now we can proceed with the actual troubleshooting.
5) Once you have your GROUND probe situation set up test it again. Stick the other meter probe into the HOT slot on your tank receptacle. If it reads the country voltage, as it should, you're good to go! Do this occasionally to reconfirm your meter is telling you the truth. A miss read could kill you.
Take the non GROUND probe and stick the tip in your tank. If it reads nothing or some tiny voltage under about 3V then presently your tank is electrically safe. But wait! You must make sure everything is powered that ever gets powered. Is the heater actually ON? Are the lights ON? Are all the pumps running? The power heads? The pH probes, the fans, the air pumps, the skimmers? The chiller? You must be thorough in your investigation. There are ways that, say, a heater could be faulty but only when it's ON. You really want to see anything that could even remotely be the problem. If you have proven to your satisfaction that nothing was left out and you have no reading, then if you were to stick your hand in, no current could flow. You wouldn't be shocked or electrocuted.
Now the flip side. You stick the non GROUNDED probe into your tank and GET A READING over 50V! This is what we fear. Now with your voltmeter stand-in you can safely and confidently proceed with hunting down the culprit. You still need to be careful as nothing has been done to prevent your being shocked. What ever you do don't bring yourself into contact with the water. Unplug all your devices and replug them in, one at a time, until the offender is found. Remove it. If it's anything that resides in the water like heaters, or power heads, or pumps, there is no way to safely repair them, discard it after cutting the power cord off. If it is something like a lighting fixture that doesn't depend on seals or potting material then you could conceivably find and repair the problem. It could be a broken or frayed wire that could be successfully repaired.
As you can see the actual troubleshooting is straight forward and easy, it's finding the GROUND that's the hardest part.
Have at it haysanatar! If you don't feel competent enough to follow this to the letter please get some help.
AND your recent experience is exactly why without exception ALL outlet powered devices in EVERY aquarium should be plugged into GFI outlets.
