Grounding Probes, GFIs, current, voltage,etc. for the electrically ungifted

[Darryl_V]

Bird with both feet on a high voltage wire = alive
Bird with one foot on wire and one on ground = dead

 

[Jewel]

nice lively debate,

 

[Pistol]

nice lively debate,

We're trying to keep it that way.

 

[Jewel]

I know you are Cal, They're just opinions after all.

 

[dale]

GFCI receptacals are under $20 at home dep

 

[Boga]

Always I wanted to understand the stray currents in a reef tank. I think it is almost impossible to measure them. This is the reason that people measure stray voltages between two points (or multiple) and then assumption can be made. Stray voltages in a reef tank should be measured in a different way compared to a pipe in ground or boat at Marina.

I see stray currents coming from:
- leakage of AC sources (heaters, pumps, T5 lighting).
- leakage of DC sources (DC pumps, LED lighting, other sensors)
- induction sources (rotating magnetic fields - pumps), which can create inductive stray currents in the conductive saltwater.
- other surrounding sources (phone, big transformer near house, natural gas line, etc)

I want to mention that whatever we talk here and call it "ground" is the house ground at the electrical panel. If you put a reference electrode outside in the ground (earth), there is going to be difference (stray?) voltage between the two. This could be one reason why if the tank is grounded, we still feel tingles on our fingers.

My system has 4 separate tanks that are connected (DT, ST, Ref, and Make Water). I placed grounding probes in each of them. Power comes from 2 GFCI's.
I think that having a grounding probe in each tank, possible leakages will be grounded "right away" and less currents will flow to DT.

Great subject Jroovers!!!

 

[AdamS]

I want to mention that whatever we talk here and call it \"ground\" is the house ground at the electrical panel. If you put a reference electrode outside in the ground (earth), there is going to be difference (stray?) voltage between the two. This could be one reason why if the tank is grounded, we still feel tingles on our fingers.

There is a potential difference between the house ground and the earth? Is your electrical panel not connected to the earth via a grounding plate and a #6 copper wire? Please explain

 

[Victoss]

[quote author=Victoss link=topic=7695.msg79994#msg79994 date=1391723186]
NEVER run a tank with a grounding probe if you DO NOT have a GFCI. What will happen is you touch something that is hot for example a light fixture that has a cut/short with your arm and you stick your hand in the tank. Now you have a nice toasty arm or your dead if your using both hands. Breakers don't trip fast enough to protect you, breakers are only meant to protect your home. GFCIs on the other hand will trip the instant they dectect an imbalance and you may get a very little shock at worst.

This being said I would still recommend the use of a grounding probe with a GFCI because now lets say your water is in contact with a neutral conductor (ie cut in your powerhead) and you touch your hot shorted fixture again, the GFCI won't trip without a grounding probe because there is no imbalance, all the current is coming from the neutral to the hot equally but going through you.

Can you explain this a bit further, I'm not quite following you. That said I have unplugged my grounding probe lol.
[/quote]

My last statement there was to explain that because of the way a gfci works if your touching a hot and a neutral at the same time with no ground the gfci would't trip. This is because a gfci measures the difference between the neutral and hot (current coming in and and current going out), it dose not measure any current that could be on the ground. If you have a grounding probe and current goes through it instead then there will be an imbalance that will trip the gfci (if over 5ma).

 

[Darryl_V]

You can measure stray current if you take a grounding probe in the water to a meter and the other end of the meter to ground.  My fluke can measure up to 10amps.  Using clamps vs. probes is best when measuring current and you should know what you are doing.

 

[Boga]

[quote author=Boga link=topic=7695.msg80069#msg80069 date=1391738753]
I want to mention that whatever we talk here and call it \"ground\" is the house ground at the electrical panel. If you put a reference electrode outside in the ground (earth), there is going to be difference (stray?) voltage between the two. This could be one reason why if the tank is grounded, we still feel tingles on our fingers.

There is a potential difference between the house ground and the earth? Is your electrical panel not connected to the earth via a grounding plate and a #6 copper wire? Please explain
[/quote]
It is relative. As we talk about stray currents in an aquarium,  the house is exposed to stray currents in the earth. So leakage coming from Hydro, pool pumps, industrial equipment or maybe the gas company is using a corrosion cathodic protection, can change the potential in various zones of the house. The panel may be connected to one point, where the house is a large area.

You can measure stray current if you take a grounding probe in the water to a meter and the other end of the meter to ground.  My fluke can measure up to 10amps.  Using clamps vs. probes is best when measuring current and you should know what you are doing.

This is the stray current from one point to the ground. If you don't have a ground probe connected, then how can be measured? So stray current in a the tank without a probe can be determined?

 

[AdInfinitum]

Great thread guys, a knowledgeable discussion.  Updating my outlets has been on my " should get around to" list for a while.  I'm moving it up to the top of the list due to this thread.

 

[KBennett]

This is the stray current from one point to the ground. If you don't have a ground probe connected, then how can be measured? So stray current in a the tank without a probe can be determined?

He said from the probe in the water to ground.

 

[Darryl_V]

[quote author=Boga link=topic=7695.msg80083#msg80083 date=1391741737]

This is the stray current from one point to the ground. If you don't have a ground probe connected, then how can be measured? So stray current in a the tank without a probe can be determined?

He said from the probe in the water to ground.


[/quote]Thats right.  Basically just putting the meter in series with probe and ground.  You can also use a clamp on amp meter which is the easier and safer way.

 

[Boga]

I think that this type of measurement would be Okay if we measure the stray currents in the ocean, where the ground (earth) is part of the system. It was discussed above that if we introduce a grounding probe, the balance will change. The system will go from "insulated" to grounded and currents will be different.

 

[KBennett]

True.  If you didn't have a probe in there before, measuring the current when you put it in does changes everything.

 

[Duke]

so if your wearing rubber boots do you not get electrocuted by putting a hand in the tank because the electricity has no way to ground?

 

[Darryl_V]

so if your wearing rubber boots do you not get electrocuted by putting a hand in the tank because the electricity has no way to ground?

As long as your only using one hand, not touching anything else,  and the rubber boots are enough of an electrical insulator than yes.

 

[Duke]

is it also true that a single GFI in series with other receptacles also protects those ones? so you only need 1 gfi per circuit breaker?

 

[Boga]

is it also true that a single GFI in series with other receptacles also protects those ones? so you only need 1 gfi per circuit breaker?

Yes. you can have more receptacles connected to one GFCI as "loads". You can have one per circuit breaker. Or more GFCI's connected in parallel, if you want separate groups of consumers.

 

[Duke]

[quote author=Duke link=topic=7695.msg80106#msg80106 date=1391744946]
is it also true that a single GFI in series with other receptacles also protects those ones? so you only need 1 gfi per circuit breaker?

Yes. you can have more receptacles connected to one GFCI as "loads". You can have one per circuit breaker. Or more GFCI's connected in parallel, if you want separate groups of consumers.

[/quote]

i fall into the "electrically ungifted catagory" .. so why would the above diagram have 3 GFCI outlets if only 1 is required?