Electrical Q

[christyf5]

but everything else on the GFCI is fine when I run it without the mag 7 so the GFCI appears to be fine (?)

[Delphinus]

I'm a little bit fuzzy on how a GFCI works in that it either implies power on the ground wire and thus a "leak", or whether there is an imbalance between hot and neutral and thus a "leak". Either way though, I'd say it's not good. I would look at that mag 7 and see if there's anything wonky with the wire where it attaches to the pump itself.

In an electrical leakage situation, the fish themselves aren't ground so they're fine (although it's still not good for them - think it can cause HLLE ?), but as a person with feet on the ground it's bad.

At least that's how I sort of understand it.

[Starry]

could always put the mag in a tub of sw and meter it for stray current. (not with your fingers standing barefoot on concreat)

[ottoman]

Is it possible that you have a bit of splash or moisture on the plug or GFCI during the water change? Just my thought.

[outacontrol]

Okay, here is how a GFCI works, it measures the current flow on the white and black wire and compares the 2 values, if the value is different by more than 6mA (0.06 amps) it will shut off the Circuit, because that current must be faulting to ground. Old GFCI receptacles had no self check circuitry in them and if they failed internally there was no indication until an accident or external test occured. New GFCI receptacles (sometimes labeled "smart lock") have an internal self check circuit and if they have an internal fault they will shut off.
So how old is the receptacle if it is newer than 2 or 3 years it might be a smart lock, and just need to be changed.
I would plug the pump into another GFCI (after checking all the wires for any damage or salt creep or moisture) and try that to see if it works.
Feel free to ask me any other questions.
I am a Master Electrician.

[Delphinus]

Everytime the question of how a GFCI works I see exactly this (which is why I said I wasn't sure). One post that says "current on the ground = trip" and one post that says "hot/neutral amp imbalance = trip". I know a few years ago I caused a GFCI to trip on an otherwise empty circuit (ie., nothing was on that was plugged in) because I touched my light reflectors and got a static shock. That suggests "current on the ground", but the "hot/neutral imbalance" makes more sense to me or at least would be a safer option because if electricity can escape out of the wires into the tank, it's not necessarily going to work it's way back to the same ground wire that the GFCI is on.

Is is possible it is a combination of both options? Sorry, I'm not trying deliberately to be dense, but I am legitimately confused since I always see the same two different explanations when this topic comes up.

Either way though - if the GFCI itself isn't faulty then it's bad that the mag pump trips the GFCI. It may be the end of the road for the pump.

[outacontrol]

the current on the ground wire would not in it self be dangerous, the danger occurs when the current leaves the wire or device and travels through you to ground.

the GFCI absolutely without doubt measures and compares the current in the hot/neutral (if you want to call it that) and respondes to an imbalance between the 2 wires of 6 mAmps.

here is a link: http://www.google.ca/imgres?imgurl=h...ed=0CCYQ9QEwCA

[Delphinus]

Cool, thanks. So, question though, why would it have tripped on the static discharge on the ground line? Does that make any sense to you? Sorry, just trying to understand why that happened. (BTW, sorry for the hijack, Christy..)

[outacontrol]

Hard to say, was the lights plugged into the GFCI? was the cord for the lights a 3 prong or 2 prong and was id a DIY or brand name bought fixture?

[Chase31]

well if you work up the static and it sends it down the "Neutral" wire it could set off the gfi, a static shock is around 5 Amps, so it could set it off