Hey, sfsuphysics .... about grounding probes
- Thread starter Len
- Start date
My opinion? Their only use is to hide a potential (no pun) problem with electricity running through your tanks and to stop you from getting zapped accidently (something that TELLS YOU there is a problem without being terribly harmful).
If you have ONE broken "thing" in your tank that has a current leak, it can't leak into the tank without somewhere to go. That usually happens when you stick your hand in the tank (doubly so if you have any cuts and you can hit your bloodstream easier) or if you have some other source to ground (ie a probe or another broken electrical appliance in your tank). Without a path to ground current doesn't flow into your tank, and no livestock is at risk. If you have a grounding probe in there you will have stray currents running through your tank and potentially harming your livestock (I'm unsure of the effect of electricity an animals, someone else will need to pipe up on that).
Of course this is only my opinion, it is possible I'm wrong
If you have ONE broken "thing" in your tank that has a current leak, it can't leak into the tank without somewhere to go. That usually happens when you stick your hand in the tank (doubly so if you have any cuts and you can hit your bloodstream easier) or if you have some other source to ground (ie a probe or another broken electrical appliance in your tank). Without a path to ground current doesn't flow into your tank, and no livestock is at risk. If you have a grounding probe in there you will have stray currents running through your tank and potentially harming your livestock (I'm unsure of the effect of electricity an animals, someone else will need to pipe up on that).
Of course this is only my opinion, it is possible I'm wrong
I think sfsuphysics is 100% correct.
I use a grounding probe and GFCI circuits to protect ME. If I break a heater or accidently push a MH into the water I don't want to be fried.
It's selfish, but my reef is secondary to my well being.
My main pumps (external) are not connected to GFCI though.
I use a grounding probe and GFCI circuits to protect ME. If I break a heater or accidently push a MH into the water I don't want to be fried.
It's selfish, but my reef is secondary to my well being.
My main pumps (external) are not connected to GFCI though.
well, from one man who was almost fried recently from having everything hooked up without any type of ground fault or probe.....I would do one or the other. I think stfsuphysics is right about it probes frying your livestock though. I have no evidence to back up his claim, just sounds like a good theory.
you sold me.
you sold me.
Guy":ivsgechs said:
I wouldn't say that, while yes a probe might help, in that it'll trip, theoretically, the gfci whenever something goes amiss, something electrically wrong in a tank isn't necessarily catastrophic.
A GFCI will trip if there's a drop in current of 5mA (I believe), and it only takes 6mA across your heart muscle to cause it to fibulate (ie send ya on a bad ride). Being as that 5mA will be through your whole body (granted cuts and other things help some of it get to your heart), you'll feel it as a nice shock at most. In the case of your GFCI failing, then a grounding probe isn't going to help either since it'll drain some of the current but not necessarily all of it, and if the GFCI failed that 5mA ceiling is no longer in place so you're still screwed.
sfsuphysics":3qcv1blx said:
I'm no electrician by a long shot but everytime I've heard about a GFCI failing it has tripped to a false alarm, not failed to trip with the real thing. I agree that if they can fail to trip during a short then they're not as useful as I thought. I actually didn't know they could fail.
Faulty units are probably possible, granted not common but still it's that level of "a grounding probe won't matter" idea I was going after.
You have to remember three important concepts behind this. 1) the neutral on your plug is also a ground, it's 0V with respect to the hot wire so everything is grounded already, it's just the ground is back at your PG&E substation. 2) Having another ground in the tank really doesn't do terribly much except give another direction for current to follow as well as the neutral of the appliance (in the case a MH or heater goes ends up both hot & neutrals will be in the water). 3) If your hands are in the tank (especially with cuts) you also become a grounding probe
So if something drops in when you're not around yes the grounding probe will pop if its sufficient current drain (might not be either if the grounding probe isn't "close enough" resistively speaking to the electrical appliance), if something drops when you're arms are in it full of scratches and cuts right to your nice conductive blood cells you'll become a path as well as the grounding probe, as well as the neutral wire, now luckily even with your reduced resistivity the other methods of "escape" probably will be "closer", but if its not much of a difference (in the case of some heaters and MH ballasts where you could easily have a few amps) you could recieve a lethal dosage of current if it wasn't for that GFCI, that's to say a ground probe might give you a false sense of security and that GFCI does everything.
Now to rebuff what Laura said, I am NOT saying anything against GFCIs, they are essential. While I've never had arms in the tank when I heard the pop, I have had plumbing issues where something overflowed and here I am standing in wetsocks in a large puddle of saltwater, although I still try to pull a spiderman and leap out of the way up the wall before it hits the surge strip.
You have to remember three important concepts behind this. 1) the neutral on your plug is also a ground, it's 0V with respect to the hot wire so everything is grounded already, it's just the ground is back at your PG&E substation. 2) Having another ground in the tank really doesn't do terribly much except give another direction for current to follow as well as the neutral of the appliance (in the case a MH or heater goes ends up both hot & neutrals will be in the water). 3) If your hands are in the tank (especially with cuts) you also become a grounding probe
So if something drops in when you're not around yes the grounding probe will pop if its sufficient current drain (might not be either if the grounding probe isn't "close enough" resistively speaking to the electrical appliance), if something drops when you're arms are in it full of scratches and cuts right to your nice conductive blood cells you'll become a path as well as the grounding probe, as well as the neutral wire, now luckily even with your reduced resistivity the other methods of "escape" probably will be "closer", but if its not much of a difference (in the case of some heaters and MH ballasts where you could easily have a few amps) you could recieve a lethal dosage of current if it wasn't for that GFCI, that's to say a ground probe might give you a false sense of security and that GFCI does everything.
Now to rebuff what Laura said, I am NOT saying anything against GFCIs, they are essential. While I've never had arms in the tank when I heard the pop, I have had plumbing issues where something overflowed and here I am standing in wetsocks in a large puddle of saltwater, although I still try to pull a spiderman and leap out of the way up the wall before it hits the surge strip
.sfsuphysics wrote:
You made several references to ground probes poping and/or triping.
I am not familar with any kind of ground probe that trips, pops, resets, or anything of the like.
Please provide a link to such a device.
My experience with ground probes is that its just simply a probe that you connect to the grourd of one of your receptacles. It simply grounds the water in your tank. That way, if a powerhead or something in your tank shorts out, it has a path to ground. If there is a continuous path to ground via a conductor, the electricity will always take that path, the least resistance to ground.
I highly recommend ground probes and wouldn't be caught dead without a GFCI near an aquarium ( or any other body of water).
Louey
Thanks!
Louey
You made several references to ground probes poping and/or triping.
I am not familar with any kind of ground probe that trips, pops, resets, or anything of the like.
Please provide a link to such a device.
My experience with ground probes is that its just simply a probe that you connect to the grourd of one of your receptacles. It simply grounds the water in your tank. That way, if a powerhead or something in your tank shorts out, it has a path to ground. If there is a continuous path to ground via a conductor, the electricity will always take that path, the least resistance to ground.
I highly recommend ground probes and wouldn't be caught dead without a GFCI near an aquarium ( or any other body of water).
Louey
Thanks!
Louey
Couldn't the use of a ground probe increase the likelihood of the GFCI working correctly?
If I understand correctly, the GFCI works by tripping when there's not as much current coming back through the neutral leg as there is going out through the hot, right? And the grounding probe gives another path for something that is leaking voltage to ground to, correct? So isn't it more likely that something leaking voltage will show the differential between the hot and neutral current (and therefore pop the GFCI) with another possible ground in the tank?
If I understand correctly, the GFCI works by tripping when there's not as much current coming back through the neutral leg as there is going out through the hot, right? And the grounding probe gives another path for something that is leaking voltage to ground to, correct? So isn't it more likely that something leaking voltage will show the differential between the hot and neutral current (and therefore pop the GFCI) with another possible ground in the tank?
Well if you mean more likely to make the GFCI trip? Then not really, the gfci will trip if there's a 5mA difference regardless of where the current goes, a ground probe, your body, or arcing through the air. Eitherway the 5mA isn't enough to kill you as long as it trips off in time.
You're correct on how a GFCI works, if 3amps are coming in the hot side, and 3 amps come out then you're golden, if 3amps come in and 2.99 amps go out, then it trips because it's missing 10 milliamps.
Basically though a ground probe will most likely pull current from a funky powerhead or something else but it won't be enough to trip the GFCI, and then you have a problem going on in your tank you really won't know about that problem, until something worse happens, without a ground probe atleast you get a little shock or something when you touch the water, pain is a good wake up call something is wrong
You're correct on how a GFCI works, if 3amps are coming in the hot side, and 3 amps come out then you're golden, if 3amps come in and 2.99 amps go out, then it trips because it's missing 10 milliamps.
Basically though a ground probe will most likely pull current from a funky powerhead or something else but it won't be enough to trip the GFCI, and then you have a problem going on in your tank you really won't know about that problem, until something worse happens, without a ground probe atleast you get a little shock or something when you touch the water, pain is a good wake up call something is wrong
OK, suppose something is leaking a significant amount of power to the tank water but the saltwater is completing the circuit allowing the stray power to get back to the neutral leg. If that could occur (just theortically speaking), wouldn't it be possible that the GFCI would not "see" enough of a difference between the hot and neutral and therefore not trip? If that scenario is possible and you put your hand in the tank, that could be bad news, no?
To me, it would seem that's one scenario where having a grounding probe in place would increase the likelihood of the GFCI working correctly and possibly making the difference in avoiding potential disaster. Not sure how realistic the situation is though...
To me, it would seem that's one scenario where having a grounding probe in place would increase the likelihood of the GFCI working correctly and possibly making the difference in avoiding potential disaster. Not sure how realistic the situation is though...
ChrisRD":8mhrvsp6 said:
Bad news? No, because if 5mA worth of current drains through you the GFCI will trip.
But you are correct if all the power(ie no less than 5mA) gets back to the neutral leg the GFCI then it won't trip, so if you are wearing thick rubber sole shoes and not standing in water (ie you're grounded and current can't get through your feet) and touch both ends of a VHO light bulb then the hot will push in current from your right hand, it'll go across your body to your left (while conviently passing right through your heart) and since you have thick rubber soled shoes current can't go to ground through you it just passes through you the GFCI won't pop off and you enjoy a nice shock (and perhaps death)
If you do the above scenario (thick rubber shoes) and stick your hand in the tank then current can't pass through you in any dangerous fashion since your hand will be at the same potential as.. your hand (since it's just one object
). Now if you had two hands in the tank it is possible that one hand can be at a lower potential than the other, but its doubtful your hands can be far enough apart to provide a significant potential difference (although it is still possible). But if current can go to ground, again 5mA difference and circuit is tripped.Bottom line if you want to be safe in the tank do a few things, wear rubber gloves (of course the chance of a leak negates their protection) or/and stand on some sort of insulating material (without saltwater dripping all over it
) A piece of wood is fine (again if not soaked with saltwater) or a wooden stool (not metal!) , or just about anything else you can think of. And if you HAVE to work with 2 hands in the tank, dont let your hands be separated by any large distance.Nah wooden gloves would be really bad since wood would absorb the saltwater
Don't know why it'd false trip during a brown out though, true the voltage is reduced but that doesn't mean less goes out, unless its specifically tuned to 120V ac.
I used to (still do) had a MH setup that would trip the gfci just about everytime it shut off. My theory on that was the capacitor was discharging too slowly or something and giving a false reading.
Don't know why it'd false trip during a brown out though, true the voltage is reduced but that doesn't mean less goes out, unless its specifically tuned to 120V ac.
I used to (still do) had a MH setup that would trip the gfci just about everytime it shut off. My theory on that was the capacitor was discharging too slowly or something and giving a false reading.
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