GFCI outlet
- Thread starter Greenpj22
- Start date
- Tagged users None
dictionaaron
Community Member
This is correct. But we should differentiate between stray voltage and broke device. With a gp and gfci Stray voltage shouldnt trip your gfci and will cause a small current flow in tank, a broken device will trip it. Without a gp completing the circuit with your body with a broken device will trip it slightly shocking u, completing it with your body strictly with stray voltage would just give u a slight tingle if anything
H@rry
Troll
Well, I guess I have been misunderstanding the term "stray voltage". I had been thinking it was coming from a faulty device that was "leaking" current into the water.
The situation that I remember was a powerhead that tripped the GFCI as soon as the ground probe was put in the water. Without the probe it did not trip. When I installed a new powerhead it did not trip with the ground probe. That led me to believe the first powerhead was leaking voltage and I was referring to that as "stray voltage". I was glad that I was able to identify a piece of equipment that was failing. That powerhead is now quietly resting in the landfill in Huntsville, AL.
The situation that I remember was a powerhead that tripped the GFCI as soon as the ground probe was put in the water. Without the probe it did not trip. When I installed a new powerhead it did not trip with the ground probe. That led me to believe the first powerhead was leaking voltage and I was referring to that as "stray voltage". I was glad that I was able to identify a piece of equipment that was failing. That powerhead is now quietly resting in the landfill in Huntsville, AL.
Jason_R
Community Member
I haven't read all the posts, but the GFCI and the grounding probe are doing 2 different things for you, both of which are good.
The GFCI detects the current flowing through the Hot leg (+/-) and compares it to the current in the return line (Neutral). If there is a difference in the current, it means that some current must be flowing elsewhere back to ground...thus its a ground fault. The GFCI breaks the circuit if it detects this scenario. This can be life saving if you become the path for current.
In the case of our tanks, if you have a pump thats got an old seal on the cable, salt water can become a path for that current. If the water is grounded with a grounding probe, then a GFCI outlet will trip quickly the instant the pump starts leaking current. The grounding probe gives you a return path for stray current in the water.
The GFCI detects the current flowing through the Hot leg (+/-) and compares it to the current in the return line (Neutral). If there is a difference in the current, it means that some current must be flowing elsewhere back to ground...thus its a ground fault. The GFCI breaks the circuit if it detects this scenario. This can be life saving if you become the path for current.
In the case of our tanks, if you have a pump thats got an old seal on the cable, salt water can become a path for that current. If the water is grounded with a grounding probe, then a GFCI outlet will trip quickly the instant the pump starts leaking current. The grounding probe gives you a return path for stray current in the water.
Otter_rs
Well-Known Member
Good explanation Jason. This is not how I had originally understood it. So you are right Harry, I just think we were talking about different things at different times. Thanks to this discussion, I do understand things better.
Brent \><{{{{*>
Sent Via the R2R Forum APP
Brent \><{{{{*>
Sent Via the R2R Forum APP
Otter_rs
Well-Known Member
I agree, the debate on that goes on. In my experience, i have not seen an obvious difference in aquarium health with or without a ground probe. I still see pros and cons to using one and I do understand its interaction with a gfci a bit better now. The one thing I think everyone has agreed upon though, is gfci's are always a good idea, if not a must.
Brent \><{{{{*>
Sent Via the R2R Forum APP
fragmatic
retired reefer
Sorry, but you can not draw power from induced voltage. You can draw power from induced current, though, IF the current is alternating. That current has to be starting and stopping. It then builds and kills a magnetic field, It is building and killing the magnetic field that causes current to flow in that near by device that is "drawing power" from the other source of current. Voltage doesn't do work nor flow. Current does work and flows. Current produces magnetic energy and magnetic energy produces current. Receiving power from a near by current source is called transformation, and is how transformers work. You can transform AC electricity and can not transform steady flowing DC electricity. Volts do no harm and do no work. Current harms and does work for us. The last time you pulled scotch tape off the dispenser you most like reached over a 20,000 volts potential in your body... and you never knew it because it did no harm. And no that is not a different kind of electricity.
fragmatic
retired reefer
Here is my best effort at explaining the volts thing.
Let us pretend I am a gold miner. Me and my partners have a long sloose box and I am lifting five gallon buckets at a steady rate and pouring water down during my shift of doing that.
My shift ends and one of my partners takes over and he is much bigger and stronger than I and he can handle the 10 gallon buckets we purchased for him to use.
Now we have more water running down the sloose box. His bigger muscles are voltage. We are getting more water because he has bigger muscles. This more water is more current. His muscles aren't going anywhere and aren't straying. His voltage is still at the top of the hill pouring buckets into the sloose. Voltage does not stray. Shorts which in this case would be leaks in the sloose box would leak current and so current does stray.
Let us pretend I am a gold miner. Me and my partners have a long sloose box and I am lifting five gallon buckets at a steady rate and pouring water down during my shift of doing that.
My shift ends and one of my partners takes over and he is much bigger and stronger than I and he can handle the 10 gallon buckets we purchased for him to use.
Now we have more water running down the sloose box. His bigger muscles are voltage. We are getting more water because he has bigger muscles. This more water is more current. His muscles aren't going anywhere and aren't straying. His voltage is still at the top of the hill pouring buckets into the sloose. Voltage does not stray. Shorts which in this case would be leaks in the sloose box would leak current and so current does stray.
Saltwater or freshwater?
dictionaaron
Community Member
This and the previous post are riddled with errors, no offense but most of what you said disagrees with electromagnetics. If u have a voltage and a resistor and a ground you have current flowing.
fragmatic
retired reefer
That is correct, if you have a resistor connected to both ends of a battery you have current flowing. But, just because you have voltage does not mean you have current flowing. Take out the resistor and leave the gap in the wire where it was. Read the voltage at both wire ends, you will read a voltage, but no longer have current flowing.
Just the same, because there is meter readable voltage in a tank does not mean there is current. In fact it "kind of" shows a lack of much current or the voltage would be pulled down, unless it is a very serious short. For example, unless there is a serious problem, if you have a voltage reading in a tank and add a grounding probe it will flow any "stray" current to ground (actually being AC it would be back and forth to & from ground 60 times a second). Now if you then measure the voltage while the ground probe is grounded it should now show only m-volts, and if you then place a current meter on that wire going to ground you will find almost nothing, if anything. It is that reading of current we need to be concerned with. After all, hold one probe of your DVM between you finger and thumb, and with the other hand hold the other probe high in the air and do not touch the metal tip. You will get a reading of voltage and sometimes this reading is amazingly high. This is what people are calling "stray voltage". It is there mostly because of the numerous electromagnetic energy sources all around us. The flux energy from these devices looses value with distance. However enough reaches us to induce a voltage in that piece of wire you held up with a meter between it and the other end. Then do it again and reach out and place your bare foot against a grounded pipe. You do not get shocked, there is a minute amount of current, but no where near enough for you to feel, and without a very expensive meter not even enough to measure. The closer you pass that other end to an electrical device the higher the voltage value will become. Again, there is voltage, and resistance, and a path to ground. This is the voltage usually found in an average aquarium, unless there is a serious problem.
If you take an electromagnet and connect one end to a battery, and do not connect the other, you only have a piece of wire wound around an iron core. You have a voltage between the open end of the wire coming out of the electromagnet and the unconnected end of the battery. However, when you connect the loose end to other post of the battery you then pass current through the winding and have electromagnetic energy. It is the current which does the work. Voltage is a reading of potential, it is not an action. Work is done when energy changes state, and with electricity energy does not change state until there is current. Current is the action of electrical energy changing state. We measure current to do calculations on how much work is being done. Or we get a current value by calculating it from readings of voltage and resistance, this is because both voltage and resistance effect current flow. As we increase resistance current decreases, as we increase voltage the inverse happens and we increase current flow. Voltage is a reading of how much potential there is to push a flow of current, resistance is a measurement of potential to resist a flow of current.
This is the current theory of electricity.
If you would, please name those "riddled with errors".
Last edited:
Just a simple question any physics. Engineering, or mathematics professor would ask after this statement. If current is proportionally related to voltage through ohms law ...
I = V/R
How can you have a voltage with no current when they are directly proportional? If you have a closed circuit hooked up to a battery with only the wire from constant to ground then your only resistance is a function of the
length of the wire and would most likely be very small small (R << 0). This would leave a very large current because any number divided by a very small number is a much larger number...
Last edited:
After thinking about it I suppose you could have any voltage with no current by rearranging the equation.
I/V = R
If you set I = 0, then R = 0, and V can equal any number because zero divided by any number is zero. I think this might an undeterminant d system though because it can be rearranged to
I/R = V
Which will give 0/0 which, I'm not positive but I believe is indeterminate. I have to check my calculus book. But this would suggest that I and R can not be zero if V contains any value.
I/V = R
If you set I = 0, then R = 0, and V can equal any number because zero divided by any number is zero. I think this might an undeterminant d system though because it can be rearranged to
I/R = V
Which will give 0/0 which, I'm not positive but I believe is indeterminate. I have to check my calculus book. But this would suggest that I and R can not be zero if V contains any value.
Last edited:
fragmatic
retired reefer
I like your thought processes,
Correct (sort of). Actually we need to take resistance high and/or voltage low. As in the battery on your desk. It reads 1.5 (ish)volts DC between the poles, however, resistance is almost ∞ through the air which is the only path available (except for tiny amount of leakage through and over the casing). Down into the amounts of currents we now pass through single gates in a processor, there is actually a tiny amount of current flow between the poles of that battery. But I think we all agree that is far out of the realm of this discussion. But for your physics answer down in the quantum math range, true, there can be no voltage without current, because there can never be an absolute ∞ resistance if you break it down far enough. (maybe in a vacuum, I have no theory knowledge at that level)
And I think this discussion is of value, many are gaining a first serious look at electronic theory. Most if not all of us have some vested interested in electronic theory because our culture now almost functions based on it working. This is the reason I stepped into the conversation, intending to try and add clarity.
Resistance and voltage are both values that control current. For some reason we (the human race) have problems separating voltage from current, this problem is and has been a source of headaches for many a professor.
Not to derail, but it is a bit like calling a scorpion fish poisonous. No, if it is injected into the body it is venomous.
Poison is ingested, venom is injected, and toxin is absorbed.
I guess that makes most coral toxic. .............................And this brings this thread to a reef related post.
Last edited:
Thinking about it even more, and thinking about what ohms law is (strictly from a mathematical standpoint)...it is a physical LAW that provides a linear relationship to mathematically explain the relationship between current and voltage experimentally observed across circuits. Resistance is a constant of proportionality that describes the relationship between current and voltage, two controlled inputs. Because of this relationship, you could never physically have a zero resistance further making it impossible to have voltage without a current without a voltage without a current and vice versa. After all current is defined through ohms law, and then physically explained as the backward low of electrons through the circuit...
fragmatic
retired reefer
Exactly. ya got brains!
And when we say no current we really mean "not enough to be of any reasonable value or consequence" in the scope of the project or circuit in question. <- my statement not out of the book
EDIT: a gold bar has a resistance value (the lowest I know of) and the fluid we call air has a resistance value.
So when I said no current in the above posts I meant of too little value or consequence in the realistic scope of the subject.
And now I will politely bow back out of this thread. Thank you for listening.
Last edited:
