Discussion in 'Reef Aquarium Discussion' started by Brew12, Oct 20, 2016.
But he wears rubber shoes
I don't know what you were looking for. You ask what the consensus is, then start writing BS about how you have a 5 watt return pump so you can't possibly get electrocuted because you wear rubber shoes.
You didn't pose a question, you just made a bunch of foolish statements.
First off, I don't think there is such thing as a 5 watt return pump. A small power head is more than that. Second, if the pump cracks open, the running wattage has nothing to do with how much current can flow through the wiring.
The only statement you made that made sense is that you don't know a lot about electricity.
There are plenty of 5w return pumps everywhere and they are great for small 10g or less tanks. I am asking a simple question when do I need to install a GFCI/ground probe? on a 2g nano tank with no electrical components except a 3v battery powered temperature gauge? on a 5 g tank with a 5w pump and a battery powered temp guage? on a 10g tank with a 50w heater, 5w pump and 3v battery powered temp gauge? I know you like your simple one answer fits all model but thats not always the case.
The answer is ALWAYS. You don't have any electronics in your sink but you need a Gfci on any outlet on the counter top.
You never know when you are going to be servicing the tank and you splash water onto the wall and into the outlet. Salt water is a great conductor. The Gfci is not only for the components in the tank.
Is the ground probe needed as well in that example?
I feel it is necessary. They cost $13. I had some sudden mysterious deaths. Maybe it was because of a shorted circulator that tripped my GFI instantly after the probe was installed. I had no idea before.
Rio RV2735 Rid-Volt Titanium Grounding Probe https://www.amazon.com/dp/B0002DGSWE/ref=cm_sw_r_cp_apa_f9d2zb3V8HKQN
I would never run a saltwater tank without the combination of the two. Immediate fatalities from 120VAC are rare. It takes a very unlikely combination of conditions to get enough current through the heart to cause near instant death. More common would be for someone to think they are fine after a shock but suffer heart related conditions up to 48 hours later. When this results in a fatality, the source of the shock is often unknown and is characterized as a heart defect. This is why most employers require anyone who has been shocked to get an EKG.
Most fatalities from 120VAC are due to secondary events tied to the shock such as falling off a ladder. I read about one particularly nasty event where a guy was using an electric chain saw without a GFCI. When he started to be shocked and clenched up it pulled the chainsaw into his leg. Now, we are rarely working on our tanks at elevation or with potentially dangerous tools but there are more than a few cases of R2R members who have needed stitches as a result of the reaction to getting shocked.
The size of the equipment doesn't really come into play. If the hot conductor is exposed to the salt water it only needs to be able to conduct 0.05 amps to cause a painful shock. Even a tiny wire can conduct at least a few amps for a short period of time.
If you have read my posts on here you will see that I don't believe fish get "shocked" in the same way people do because the seawater around them is more conductive than they are. I do believe the voltage field around them can cause HLLE or other issues. My biggest concern is that if I am leaking voltage into my system I am also likely leaking copper from the wire into the system. Copper will corrode very quickly in saltwater if current is running through it. If the fault is generating heat it is likely leaching toxins from the plastic into the water. If it is a motor, potentially toxic heavy metals may be being released into the water from the magnets and motor windings. I want to catch this as quickly as possible which a GFCI/ground probe combination can do.
Basically almost all of the electrical gear, except power heads, are in the sump. If you place the grounding probe in the return chamber then the probe will most likely be the shortest path of resistance for the electricity to travel. I'm not an electrician, but as a lead cable technician, that's what they always taught us with grounding from the street and the house.
I would seriously doubt that the interference on your Apex is coming from the aquarium water. I would check for a few other things before going the water route. I have seen Apex pH probes show "noise" from other, non related modules being dirty or developing salt creep. You can also get noise by having the Apex wiring, either to the probes or other modules, being bundled together with other power cords. This is made worse if the cables go to DC pumps.
I'm glad that you understand the importance of surface area when it comes to high frequency grounding! You have a much better understanding than most! I do need to point out that it does work a little different in a salt water aquarium. Normally we use shielded cables with either mesh or foil to provide surface area which then goes to a drain which we connect to ground. In our tanks it is the salt water that acts like the foil and the ground probe is just a convenient drain point. With the low current densities involved even a very small ground probe will make an adequate drain for almost all frequencies.
I love experimenting myself so have fun with this!
Just keep in mind that there are no true hobbyist level DC motors. A DC motor MUST have an electrical connection to the rotor. If you can pull the rotor on the pump then it is an AC motor. The controllers on the DC pumps convert the 120V, 60hz, AC from our outlet into DC. It then converts it back to some form of AC. This AC is typically PWM or a modified sine wave. To get a good idea of what is going on you will see it best with an oscilloscope. At the very least you will need a voltmeter that reads "True RMS" and not one of the cheaper ones that calculates RMS based on peaks.
My compliments and thanks for a very good discussion. Is it possible though to be illuminating and confusing at the same time? I've done some residential wiring and immersed myself in the l0cal code to stay safe so I'm not a complete noob, but I've struggled with some of the finer details being debated. From what I've gathered, a ground probe is a good thing to have in your system, ideally in every tank that has electrical equipment that can fail, as it provides an alternative path for stray current. A GFCI is also recommended because it trips when the current leaving doesn't precisely match the current returning. Best though is when the probe is plugged into a GFCI although the risk passes from the person to the system meaning that stray voltage could lead to everything on that GFCI shutting down unexpectedly. As most have said, this is an easy decision to make. Let me know please in the simplest terms possible if any of the above is incorrect. I don't yet have a grounding probe but will get one for all of my closed systems including QT and heated water change tanks. Thankfully, all of my equipment is already powered by circuits with GFCI protection.
A few additional questions though...
- I'd like the protection of a grounding probe while minimizing the risk to system. Is it possible to plug a GP into a portable GFCI which is plugged into a GFCI receptacle such that when it trips it only trips the portable one? This way I am alerted when something is wrong without risking everything else plugged into that circuit? I say this because 3 or 4 circuits power all of my equipment and it would be difficult to isolate the equipment more susceptible to damage.
- is it possible to ground a GP with the ring terminal by attaching it to copper pipe or does it have to ground into a grounded outlet? Is there any other suitable way to ground such a probe using the ring terminal?
- Slightly off topic but referenced earlier in this thread, did I understand correctly that those plastic outlet boxes are not properly grounded? I used them exclusively when I wired my basement and I'm not very nervous that this was not safe. The work was done with permit and with inspection by the local electrical authority, and I question why they would sell such things with grounding screws included if they were not safe. I hope I got it wrong.
Thanks in advance, and thanks again for a very helpful discussion. Andrew
I have an Apex Jr controller with 2 EB8 power bars. I run a large power strip which is plugged into a Gfci wall outlet. On the power strip I have 3 portable GFCIs which I have both EB8 power bars and the Jr is in the other. This way if something on an EB8 trips, I don't lose the entire system, just the one power bar.
I'm glad you've appreciated the discussion!
Just to clarify a few things.
It depends what you are calling a stray voltage. An induced voltage will not cause a GFCI trip. A fault voltage will cause a GFCI trip.
It does not matter where you plug the ground probe into. I plug mine into a regular wall outlet. You just need 1 per system.
If you have titanium heaters with a 3 prong plug then you already have a ground probe. You only need a separate ground probe if you have 2 prong heaters such as the glass ones.
If your copper pipe is properly bonded to your homes ground you can connect it there using the ring terminal.
Plastic outlet boxes cannot be grounded but that does not make them unsafe. You do need to make sure that the ground you run to your outlets is properly connected. It is only the metal conductive boxes that are required to be grounded.
Yes, titanium heaters make a great ground probe. The outside metal case is directly tied to the ground on the plug. My first saltwater build consisted of 4 Hydor Korllia wavemakers pumps, one started leaking voltage into the tank. First time it happened I thought the Finnex heater was at fault. After several hours of trouble shooting I traced the problem to one of the pumps. After 4 more pumps did the same thing I finally came to the the conclusion that although the pumps are cheap it’s just not worth the aggravation! After some trial an error, 2 circuits feed my tank, one feeds the heaters and non- critical items while the other has lifesupport items on it so if the GFCI trips on the heaters the tank will be ok for a while.
Several months ago GFCI’s saved me a bunch of money when the power company had a transformer go along with a software error, sending a huge voltage spike into my house. Several houses caught on fire, numerous TVs and AC units where trashed. I had 4 surge protectors burn out saving a printer and TV. The resulting smoke prompted me to call the fire department in as I had no clue what was happening. All the Gfci’s on that phase in the house tripped including my tank and fishroom preventing a huge voltage spike which I’m sure would have trashed every AC pump.
You may feel a tingle in the water when voltage is there and you are NOT grounded. If you are grounded it’s a different story! Ground probes and Gfcis are standard equipment for me!
Thanks everyone, very helpful and wise advice.
Isnt a bathtub grounded by the metal drain? How would someone electrocute themselves if its grounded?
Fresh water and salt water act completely differently to electricity. You could not shock yourself in a tub with a grounded metal drain if it were filled with salt water. With fresh water you would need to touch the device that was in the tub and the drain at the same time. Of course, some tubs are cast iron and will conduct so you would only need to be touching the electrical equipment.
Ah okay. Thanks.
Whats safest for the fish and coral?
Ive got my diy probe connected to the copper water pipe. When im wearing boots in the basement i feel nothing touching the water. When i wear socks i feel a tingle. So is my ground probe not working? Or is it simply my feet has much more surface area than the probe?
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