Ground Fault Interrupter vs. a Grounding Probe

[leafyseadragon]

Given that salt water conducts electricity better than fresh water, I would like to protect myself from accidental shock.

Would a grounding probe suffice, or would I need a more expensive device like a ground fault interrupter? And could I connect my entire power strip to the GFI to protect myself from all my electrical devices?

And advice would be appreciated.

 

[ReefRaff]

you should have both, and you can get a GFI power cord at the home depot if u don't want to install an GFI outlet. If you do install an outlet, then pluging a power strip into that makes it part of the GFI curcit.

 

[fishfreek]

The GFI outlet will save your life in an instant. Infact a GFI outlet should be suggested for anyone with aquariums not just saltwater folks.

The grounding probe is designed to drain off the minute voltate leaks that some of our equipment could/do put off. A spinning magnet within the power head can produce an external magnetic field unless its properly sheilded internally. This magnetic field in water that is disturbed could produce microvolts of electricty.

Many of our fish have very sensitive lateral lines that pick up this minute amount of electric and can cause the fish constant stress. Some have clamed that adding a grounding probe can help prevent/cure laterl line disease.

 

[Biggen]

Go with a GFCI. They can/will save your life.

A probe is simply completing an electrical circuit. You can still get shocked with a grounding probe. Not so with a properly functioning GFCI.

The probes are supposed to remove "stray voltage" from the system. But what doesn't make sense to me, is that if stray voltage has no where to go, it can't pass current. However, once your complete the circuit, you system can now pass current and everything in your tank has the possibility of getting zapped from the amps now being drawn.

Its kinda like the bird on the power line. Even though the bird is sitting on a 100,000 volt power line there is no circuit to ground. So even with the potential (voltage) of 100,000 volts the bird is fine. However, if that same bird should touch the pole and complete the circuit, it is instantly fried...

 

[Biggen]

Many of our fish have very sensitive lateral lines that pick up this minute amount of electric and can cause the fish constant stress. Some have clamed that adding a grounding probe can help prevent/cure laterl line disease.

I know a lot of people say this but I am not so sure. Most fish lateral lines do not detect electrical current. They detect differences in water pressure. similar to the way our ears detect differences in sound pressure. Only sharks and certain other bony fish are able to detect voltages in the water.

Now I have no idea exactly what bony fish are adapted to detecting voltages. But that would something interesting to research.

 

[leafyseadragon]

Is this one good enough? I found many in the $50 range, this one is $25. Anybody know anything about this model?

http://www.amazon.com/exec/obidos/t.../ref=sr_1_1/102-4641975-3660113?v=glance&s=hi

 

[Biggen]

Yeah it will work, but it would be cheaper to either replace the regular breaker with a GFI breaker (what I did) or replace the outlet with a GFI outlet. GFI breakers run around $35 while GFI outlets are around $15.

I would only buy what you are looking at if you are not comfortable replacing the breaker or outlet yourself. You will probably need several of those extension cords since I am sure you will need more than the 3 outlets that come on it.

 

[peterp]

Neat, I did not know you could get a extension cord with a GFI in it.

IMHO It should work so long as the receptical you plug it into is really grounded.
I've only used the ones that replace an existing in-wall socket.

 

[leafyseadragon]

Thanks to both of you for the reply.

Biggen, replacing the breaker or the outlet is not an option for me. My tank is in my office, and I don't think my employer would like it if I rewired my office.

 

[Biggen]

IMHO It should work so long as the receptical you plug it into is really grounded.
I've only used the ones that replace an existing in-wall socket

Ok. I am being a little picky. But I thought you might like to know how a GFI works.

In a perfect electrical world, incoming (hot) current is run through a electrical device and then the exact ammount that was hot is now returned through the outgoing (neutral) wire. It is basically a loop from the transfer station. A GFI constantly monitors the outgoing current to make sure it is the same amount as incoming. If it detects that even the smallest difference in current between these two (4 milliamps), it trips the circuit thus shutting off power.

It doesn't have anything to do with ground. That is a whole other class...

 

[peterp]

Thanks for the explanation! It is always good to know how thing work.

My fuse panel is old, no breakers, so the in wall's replacements are the only way to go without replacing the main panel

 

[Biggen]

My fuse panel is old, no breakers, so the in wall's replacements are the only way to go without replacing the main panel

Ohhh yeah... It will be much cheaper to buy some outlets... Re-wiring a building totally blows. I am fretting having to do it soon to a building we just bought...

 

[ellisz]

Would swapping an outlet with a GFI outlet the put every other outlet behind the one you replaced on the GFI? Sometimes a GFI can be a hassel.

A surge with a GFI seems like a good idea.

 

[Biggen]

Would swapping an outlet with a GFI outlet the put every other outlet behind the one you replaced on the GFI?

As long as they are downstream of the GFI, then yes, it will protect the entire circuit. Threre are are two pairs of connections on a GFI outlet. One labeled "Line" and the other "Load". Make sure the incoming hot is connected to "Line". Then if you connect the "Load" to the rest of the downstream, it will protect everything downstream of the outlet.

Downstream in this sense means that the electricity must pass through the GFI before it reaches the outlet(s).

It may sound a little complicated but it is really easy to hook these up.

 

[ellisz]

My point was that by adding the GFI outlet for the tank, you are actually putting other outlets on the GFI as well.

You could therefore have the GFI kick for an outlet other than the on on the tank and have the tank lose power too.

This is probably not a big deal most of the time. I know I have seen many people that have fridges or freezers in the garage lose power and think the unit died when actually the outlet was tied to a tripped GFI. Kind of depends on how good or bad the wiring was done in the house. Some new houses can have a lot of outlets on one circuit.

 

[Biggen]

My point was that by adding the GFI outlet for the tank, you are actually putting other outlets on the GFI as well.

You could therefore have the GFI kick for an outlet other than the on on the tank and have the tank lose power too.

Oh, ok. I thought you were asking if you "could" do it? I misunderstood...

Yeah you are right about another device tripping the GFI even though that device wasn't on the actual GFI itself. This is the number one reason to run a dedicated circuit to the aquarium...

 

[ellisz]

Yeah you are right about another device tripping the GFI even though that device wasn't on the actual GFI itself. This is the number one reason to run a dedicated circuit to the aquarium...

That is a good point! I am finishing my basement where the tank will end up. I am wiring a dedicated circuit for the hot tub, better do the tank too.

Great idea

 

[two11devan]

[ If it detects that even the smallest difference in current between these two (4 milliamps), it trips the circuit thus shutting off power.

It doesn't have anything to do with ground. That is a whole other class...

I could be wrong here, but I thought the ground was a very important part of the GFCI. If the gfi is not grounded properly, it will not work correctly. In some older houses with the two pronged outlets, it is necessary to ground it by either running a bare copper wire to the box if it is metal or a better alternative would be to ground it to a cold water pipe under the house.
If there is a leak in the curren't the GFI will shut the power off at the breaker and the power that is leaked will go through the ground and not through you.

 

[Biggen]

By definition, the GFI really doesn't have anything to do with ground. It is simply monitoring "traffic" to make sure all the current that comes into the device also goes out in equal number.

Now of course you should ground it just like you should ground everything electrical. This will prevent equipment from being destroyed.

If there is a leak in the curren't the GFI will shut the power off at the breaker and the power that is leaked will go through the ground and not through you.

There has to be a physical connection from the leak to the ground. For instance, say there is potential (voltage NOT current) in the aquarium because a device is malfunctioning. Just because you have a ground on the outlet doesn't mean the voltage will magically "jump" to that ground. There has to be a connection. You, standing on the ground, will make that connection when you put your hand in the water. As soon as the GFI sees that the current is now leaking, it will trip.

If you could magically levitate and then touch both the hot and neutral prongs on a GFI protected circuit, nothing would happened. You wouldn't get shocked and the breaker wouldn't trip. You would have voltage (potential) running through you but no current. But as soon as you contacted ground.... ZAP!!

 

[ReefRaff]

In a perfect electrical world, incoming (hot) current is run through a electrical device and then the exact ammount that was hot is now returned through the outgoing (neutral) wire. It is basically a loop from the transfer station. A GFI constantly monitors the outgoing current to make sure it is the same amount as incoming. If it detects that even the smallest difference in current between these two (4 milliamps), it trips the circuit thus shutting off power.

It doesn't have anything to do with ground. That is a whole other class...

Ditto.