Let’s revisit Ground Probes and Stray Voltage (1 Viewer)

[Reefahholic]

You may have your solar and generator ready for hurricane season, but what if a different disaster strikes before that? Will your corals make it? What about all your fish?

Who’s running one. Send me a link please.

 

[TX_Punisher]

Always had one. I figured you were up to something asking about multimeters.

 

[Reefahholic]

Always had one. I figured you were up to something asking about multimeters.

I want both. Just trying to figure out the right ones to get without breaking the bank. Ground probe is cheap. Multimeter can get pretty expensive, but not sure what’s really needed. I hear analog is better.

 

[slojim]

I picked up a ground probe one day at All about Fish when I stopped on the way home to grab some food a few years ago. Don't recall the brand. I plug it into a kasa bar with energy monitoring - I think I should be able to see current if there is any - but so far, so good. In theory, I could figure out an automation to trigger a light coming on or something if it has a significant reading - but I haven't done that.
I have an old Fluke77 I used to use at work, it's at least 20 years old and has put up with plenty of abuse. If I lost it, I'd likely replace it in kind since it has been good to me, but basic voltmeters are cheap and it's more capable than most of us need on a routine basis for household power.
If you get a less expensive type, especially an analog type, they may be less protected, so make sure you test it after you use it - for example, if you check something has zero volts, you should then go check a known hot source and make sure it reads what you expect (like 120V at an outlet for AC) - to make sure that zero is really zero, and not a blown fuse or burnt connection. I do this anyway with my fluke most of the time if I'll have my hands on something.

 

[foos]

I plug it into a kasa bar with energy monitoring - I think I should be able to see current if there is any - but so far, so good

That energy bar almost certainly only has current measurement on the hot, not the neutral or ground so it will never return any thing for current over the ground from a ground probe.

 

[foos]

Ground probe + GFCI. Neither alone is going to do you any good. GFCI measures current on the hot and neutral to make sure that all that goes "out" on the hot comes "in" on the neutral. Alternating current doesn't really have an out and in but is often referred that way for simplicity. The GFCI monitors that difference and is designed to trip before the difference is enough to kill you if it is going through you.

A ground probe alone just gives that stray current from a damaged heater or whatever somewhere to go. Result is the exposed wire corroding and if copper you are dosing copper to your tank. The flowing of current in salt water also does some nasty chemistry and one of the things you get is chlorine gas, but in low levels it will dissolve into your water making it so you are basically dosing bleach and copper.

A GFCI alone will not trip and you will still have the dissolving of the exposed conductor and possible dosing of bleach. The difference is that if you are messing around in the sump, spill a little water, reach in and grab the busted heater or possible even get close to it, you will get the shock of your life but the GFCI should trip soon enough that you can live to talk about it unless you have heart conditions. Ground probe only.... there is a good chance someone else tells the story at your wake.

Moral of the story, you need a GFCI so faulty equipment does not kill you, and you need a ground probe so it trips before killing your fish and coral or you come to the shocking discovery there is an issue.

 

[slojim]

so let's see, the current path will be from the fault to the probe to the ground prong in the outlet - yep, I missed that, I agree that the current monitor won't catch that - so thanks. Glad I posted that.
Interestingly enough, the only outlet near my tank also feeds the refrigerator, and to add one necessitated going through an exterior wall - I chose to hire that out. The electrician told me had had a SW tank, told me some shops he likes, and also suggested I reconsider the GFCI - he doesn't use them on his tanks due to fear of false trips. But instead, I had him install 2 independent GFCI's - and I split some critical loads. Not failsafe, if it tripped on vacation it's probably not good enough to keep the tank alive for a week, but I think it will be fine for a day or 3.

 

[foos]

Yeah, I have two with critical loads split and alarms set on the apex since nuisance trips do happen. I have a Vectra L2 for the return pump and if I planned on leaving for a long time I would wire up the battery backup port to a dc power supply on a different breaker without GFCI.

 

[Reefahholic]

I have a GFCI…no GP yet. I only have two outlets behind the tank, and I don’t believe you can plug into a power strip. I need to be a regular outlet because they have the ground wire that attaches to the screw in the middle of the outlet. I mean, I guess I could buy a 20’ GP and run it from another outlet nearby.

 

[foos]

Ground probe I have plugs into a regular outlet and just has plastic pins for hot and neutral but a metal one for the ground. They can be plugged into a power strip.

 

[Reefahholic]

Ground probe I have plugs into a regular outlet and just has plastic pins for hot and neutral but a metal one for the ground. They can be plugged into a power strip.

What about the little ground wire? I wish I could plug one into a ADJ power strip, but that probably won’t work because there’s no place to attach that ground wire. I’m lost when it comes to electricity.

 

[foos]

Have not seen one like that but they are probably both connected and they add the wire to give options. Can always get and check with a multimeter.

 

[BeltwayBandit]

Ground probe + GFCI. Neither alone is going to do you any good. GFCI measures current on the hot and neutral to make sure that all that goes "out" on the hot comes "in" on the neutral. Alternating current doesn't really have an out and in but is often referred that way for simplicity. The GFCI monitors that difference and is designed to trip before the difference is enough to kill you if it is going through you.

A ground probe alone just gives that stray current from a damaged heater or whatever somewhere to go. Result is the exposed wire corroding and if copper you are dosing copper to your tank. The flowing of current in salt water also does some nasty chemistry and one of the things you get is chlorine gas, but in low levels it will dissolve into your water making it so you are basically dosing bleach and copper.

A GFCI alone will not trip and you will still have the dissolving of the exposed conductor and possible dosing of bleach. The difference is that if you are messing around in the sump, spill a little water, reach in and grab the busted heater or possible even get close to it, you will get the shock of your life but the GFCI should trip soon enough that you can live to talk about it unless you have heart conditions. Ground probe only.... there is a good chance someone else tells the story at your wake.

Moral of the story, you need a GFCI so faulty equipment does not kill you, and you need a ground probe so it trips before killing your fish and coral or you come to the shocking discovery there is an issue.

With a ground probe the GFCI will trip as soon as there is stray current. The ground probe, if done properly, directs stray current to the third (ground) leg so to would create an imbalance that would trip the GFCI.

 

[soymilk]

The little wire is suppose to be screwed into the little screw connecting the wall faceplate.

Thats suppose to connect ground for houses that are wired old with two wires and no ground back in the day.