this is the best summary I found and believe after spending too much time figuring out what I needed for best protection of me and the reef. I conclude that probes and gfci should be installed - GFCI selectively and probes turned off EXCEPT when you are going to get wet - BECAUSE THEY CAN CAUSE THE gfci TO TRIP MORE OFTEN WHEN YOU ARE AWAY AND DON'T WANT EQUIPMENT DOWN - sorry for caps
from
http://reefcentral.com/forums/showthread.php?s=&threadid=1463164&perpage=25&pagenumber=3
a summary of issues and answers:
posted by jdieck
Should people without a GFCI install a ground probe?
That question has a very simple answer:
People without a GFCI should install a GFCI, that simple.
Now; if you like to get into complexities and instead ask the question:
Will a ground probe installed without a GFCI make the system safer?
The answer is a bit more complex. For it to be safer it shall meet the condition that it must trip the breaker under all conditions:
a) Will the breaker always trip if there is a direct short?
The answer is no; not always.
Because the current required (15 Amp or 20 Amp depending on the breaker) is in turn dependent on the salinity level (Amount of movable dissolved ions), the temperature, the size of the electrodes (probe and broken or bare wire) and the quality of the connection under some conditions it will trip and under others it will not.
If you want to properly test then you will need to replicate all this variables at different levels but why to do it if you already know that there will be conditions it will not trip under?
b) Will the breaker always trip if there is an arc fault (like a false contact on plugs)? The answer again is no as you already know that you can sustain a good sized arc enough to create a fire at a current way below 15 Amps.
c) Will it be safer for the aquarist to touch a shorted lamp and the water when the probe is present?
The answer again is no. With the water properly grounded the aquarist will also be very well grounded so a higher current will pass trough him resulting in a more serious shock.
Without the probe the current through the aquarist must pass to ground by passing as an example, through his feet, the sole of his shoes and the the material the floor is made off or covered with. In this case all those materials will present an added resistance (Say wearing rubber soled snickers or standing on a dry carpet or wooden floor he will not even be shocked) thus making it less serious.
So in my own opinion testing is not needed because you can put together already known facts to know the answer.
Finally will it be safer for the aquarium critters having a probe without GFCI?
First remember that the breakers are there to protect the wiring not the people or pets. They are very slow to act compared to a device like a GFCI and they need such a high current to activate that by the time they do (even if milliseconds) the current will be enough to cause damage not only by itself but alos by the increased level of toxins released by the increased damage to the defective device or by released oils by the burned equipment.
So, in summary to the question:
Should people without GFCI install a grounding probe?
The answer, for the reasons stated above is no and people without a GFCI should install a GFCI which is designed to protect people not wires.
That cleared out of the way then, a new question might be:
Should people with GFCI install a grounding probe?
Again the answer is simple. Installing a ground probe will help trip the GFCI any time a short to water is established. Because that could happen any time you may decide not to add the probe if you consider it too risky to have it trip when you are not around to fix it. If this is the case just note that if you do not install the probe it may not trip until you yourself make the circuit to ground meaning that you will be at risk if the GFCI is faulty.
Conclusion: Why to test for something you already know the answer to?
You may not know if the breaker will or not trip only with a probe but because the action is always to have GFCI why to care about a probe only case? Just install the GFCI for your own sake. Anything else will be over-engineering an unnecessary answer.
Enjoy!
__________________
Did I write what I wrote? What the heck am I talking about! Well..... Nevermind.
<a href=showthread.php?s=&postid=13704765#post13704765 target=_blank>Originally posted</a> by InsaneClownFish
I'm buying a voltage meter on my way to work today. :thumbsup: Marc, any thoughts on using a ground probe? I've been reading alot of a mixed bag regarding using them. Also, are they really necessary with a GFCI? Anyone have any more thoughts about this?
I think I'm just extra sensitive to it because of all these factors.
