Electrical Q

Delphinus · #1 03-20-2010, 05:54 AM

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 · #2 03-20-2010, 06:00 AM

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 · #3 03-20-2010, 06:25 AM

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 · #4 03-20-2010, 06:50 AM

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 · #5 03-20-2010, 07:17 AM

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

Doug · #6 03-20-2010, 01:37 PM

Christy if you remember the time I had the leak in the stream pump that caused the arc from the halide fixture to my head,

, it never tripped out a standard plug but tripped the gfi plug in. I could also measure that leak with a meter from my tank to ground.

muck · #7 03-20-2010, 01:43 PM

Had a Mag 3 pump leak current on me.
Found out when i went to adjust it while it was running in my saltwater mix bucket with my hand. BAZAPP!!

Delphinus · #8 03-20-2010, 06:21 PM

Quote:

Originally Posted by 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?

Does it really seem hard to say? The static charge went down the ground wire because the reflector was grounded. Nothing else was on at the time. No current leaked to the hot or neutral wires. Just the ground. Zap. Ground wire. GFCI tripped despite nothing plugged in was on. So it just seems fair to me it could be a combination of current imbalance between the hot and neutral ("black and white") wires and checking for any potential capacitance or whatever it's called, on ground. Ah well. It doesn't really matter to me. Point is it shouldn't be tripping.

Christy - my suggestion for the easiest thing to try is find another GFCI outlet (eg bathroom plug), turn it on and see what happens. If it trips you know it's not the plug. If it is the plug though then at least that's cheaper than a new Mag7.

But I've had Mag drives leak current after a few years of use. I think they get little microfractures in the housing over time. Not sure the explanation though.

PoonTang · #9 03-20-2010, 07:04 PM

may also be that since you had just done a WC than there were splashes and dribbles all over the place around your sump. If you created a path to ground through a simple dribble down the outside of your sump that may have been enough to let the GFI trip. Give it a try today now that everything is dryed out.

outacontrol · #10 03-20-2010, 07:36 PM

[quote=Delphinus;503726]Does it really seem hard to say? The static charge went down the ground wire because the reflector was grounded. Nothing else was on at the time. No current leaked to the hot or neutral wires. Just the ground. Zap. Ground wire. GFCI tripped despite nothing plugged in was on. So it just seems fair to me it could be a combination of current imbalance between the hot and neutral ("black and white") wires and checking for any potential capacitance or whatever it's called, on ground. Ah well. It doesn't really matter to me. Point is it shouldn't be tripping.

WTF!

IS THERE A REASON YOU ARE MOCKING WHAT I AM SAYING? DO YOU HAVE ANY ELECTRICAL TRAINING?
I helped you when you could not get your 3-way switching working. Not impressed at all.
Did you read any of that link that I posted? A GFCI does not function any other way than I described it measures the current on the 2 current carrying wires (the hot and the neutral that you like to call them). It does not measure or check for current on the bare bonding wire (or ground as you like to call it) at all. Period no questions about it.