stray voltage test

helpme74

Member
My apartment building has old wire 2 prong outlet with no ground. If I put a gfi plug in and run a new ground from my copper water line to my gfi that would be a good ground right? also when testing for stray voltage I put one end of my volt meter to the gfi ground and the other end in my sump water and I’m getting 00.8 volts this means no stray voltage right ? Am I testing it right?
 

reefraff

Active Member
Originally Posted by helpme74
http:///forum/post/2713730
My apartment building has old wire 2 prong outlet with no ground. If I put a gfi plug in and run a new ground from my copper water line to my gfi that would be a good ground right? also when testing for stray voltage I put one end of my volt meter to the gfi ground and the other end in my sump water and I’m getting 00.8 volts this means no stray voltage right ? Am I testing it right?

Correct on all counts. .8 volts is stray voltage, it just isn't excessive stray voltage.
 

wattsupdoc

Active Member
Originally Posted by helpme74
http:///forum/post/2713730
My apartment building has old wire 2 prong outlet with no ground. If I put a gfi plug in and run a new ground from my copper water line to my gfi that would be a good ground right? also when testing for stray voltage I put one end of my volt meter to the gfi ground and the other end in my sump water and I’m getting 00.8 volts this means no stray voltage right ? Am I testing it right?


This test is IMO inconclusive, .8 volts is nothing. Use an analog meter for more accurate results.
 

sly

Active Member
This test is inconclusive. When you ran an independent ground to a copper water pipe you created a ground loop. In other words, the ground your house is using is not the same ground that the GFCI is using. Often times you will have a voltage difference when you run two independent grounds like this.
Your house DOES have a ground... just not one run separately like modern day wiring. The neutral on your outlet is run to ground. This is either the wide blade (on a polarized outlet) or the white wire (if they even wired it correctly). I'll bet that if you check the voltage between your neutral wire and the ground wire that you created, you will see that they are not showing 0 volts. There will probably be SOME voltage between the two even though they are both technically a ground.
Do you ever have a problem with your GFCI tripping?
I personally wouldn't worry about 0.8 volts in my tank. It is probably an error on your testing method due to there being a ground loop. I had stray voltage once and it was more like 20 volts. It turns out my UV light had water leaking through it due to a bad seal and was energizing the water.
FYI, if you do have a voltage leak, it will be AC not DC. If you are showing DC voltage then that is not a voltage leak. The saltwater acts as a conductor and when you stick two dissimilar metals in the tank they can create DC voltage just like a regular battery.
 

helpme74

Member
I made a box up for my GFI that has a plug so i can plug into my old 2 prong outlet. and from the gfi box i'm using the same ground from water pipe to test for stray voltage .

 

ibew41

Active Member
Originally Posted by Sly
http:///forum/post/2714069
This test is inconclusive. When you ran an independent ground to a copper water pipe you created a ground loop. In other words, the ground your house is using is not the same ground that the GFCI is using. Often times you will have a voltage difference when you run two independent grounds like this.
Your house DOES have a ground... just not one run separately like modern day wiring. The neutral on your outlet is run to ground. This is either the wide blade (on a polarized outlet) or the white wire (if they even wired it correctly). I'll bet that if you check the voltage between your neutral wire and the ground wire that you created, you will see that they are not showing 0 volts. There will probably be SOME voltage between the two even though they are both technically a ground.
Do you ever have a problem with your GFCI tripping?
I personally wouldn't worry about 0.8 volts in my tank. It is probably an error on your testing method due to there being a ground loop. I had stray voltage once and it was more like 20 volts. It turns out my UV light had water leaking through it due to a bad seal and was energizing the water.
FYI, if you do have a voltage leak, it will be AC not DC. If you are showing DC voltage then that is not a voltage leak. The saltwater acts as a conductor and when you stick two dissimilar metals in the tank they can create DC voltage just like a regular battery.
why would the copper pipe create a ground loop it is also bonded to your ground system and the cold water line is the main ground in a home service if you have metal pipes and city water
 

wattsupdoc

Active Member
Most likely it wont create a loop. The two are bonded together. However the water pipe is bonded to ground for your protection and is not intended to be a source to bond to. If copper it would be a good conductor. But if it's iron where it.s bonded at which "MAY" be the case, it's not a good conductor. My point is bonding to the house plumbing is not the best method at all. It may work, but not a good idea. For a better understanding of whats going on when your reading .8 volts, which by the way is only half the voltage a a standard alkaline battery, (C,D, A, and AA's) So like a dead AA battery.
Read this.
https://www.saltwaterfish.com/vb/show...ht=electricity
BTW IBEW the cold water line is not the main ground in the building. It is a system which is capable of being energized and is required to be bonded. Also, a cold water pipe MAY be used for a grounding electrode if it is connected to within 10 foot of where it enters the ground. BUT it is an electrode that must be supplemented. The rod is the primary ground it needs no supplementing AS LONG AS it has less than 25 ohms to earth. Or Eufer, or building steel all are not required to be supplemented.
 

helpme74

Member
I have copper pipes and I live on the second story of my apartment building. My building is surrounded by cement the only place I can get a ground is the cold water copper pipe. I don't ever have a problem with my GFCI tripping?
 

sly

Active Member
Check the voltage between your ground and your neutral. If there is a difference then you have a ground loop. Is the voltage you are seeing AC or DC?
If it's not a problem with a ground loop then it could be because of your fluorescent lights. Try turning them off and see if your voltage changes.
 

sly

Active Member
Originally Posted by wattsupdoc
http:///forum/post/2714640
But if it's iron where it.s bonded at which "MAY" be the case, it's not a good conductor.
"If" it's iron then it will provide greater electrical resistance than would a standard copper conductor house ground. This would mean that under load there would be a voltage differential between the two grounds. A voltage differential between grounds is a ground loop. It's always best to use one ground in a system (especially if slight voltages differences are important)
 

wattsupdoc

Active Member
Whenever you have anything being used on the circuit, you will have potential between neutral and ground. The neutral is a current carrying conductor. It is not an indication of a loop and in order for a loop to be an issue you have to have a poor connection to earth. BTW, there is no problem at all with having two grounds, that is in fact what you have if you are utilizing a cold water pipe ground and a ground rod set. The cold water pipe ground is a separate entity from a cold water BOND.
I cannot tell you that you have an adequate ground by bonding to the cold water pipe. If the apartment has plastic piping anywhere in it between a direct path to the earth, then you in fact DO NOT have an adequate ground.
 

ibew41

Active Member
Originally Posted by wattsupdoc
http:///forum/post/2715199
Whenever you have anything being used on the circuit, you will have potential between neutral and ground. The neutral is a current carrying conductor. It is not an indication of a loop and in order for a loop to be an issue you have to have a poor connection to earth. BTW, there is no problem at all with having two grounds, that is in fact what you have if you are utilizing a cold water pipe ground and a ground rod set. The cold water pipe ground is a separate entity from a cold water BOND.
I cannot tell you that you have an adequate ground by bonding to the cold water pipe. If the apartment has plastic piping anywhere in it between a direct path to the earth, then you in fact DO NOT have an adequate ground.
if you live an apartment then I would not trust the copper pipe if there was a leak and a plummer spliced a rubber or plastic part in then you will have problems
 

reefraff

Active Member

First off a GFCI doesn't even need to have the ground wire hooked up to work properly. By not hooking up the ground you are simply not providing the additional protection that third prong provides. The GFCI will still trip if there is a varience in the current leaving the Hot and going back in the neutral. The ground line simply provides an additional path to ground.
If you are in an apartment the copper waterline might not actually be a great ground unless you know for sure it is copper all the way to the ground as in dirt. It could have a non conductive material at some point isolating the copper from the earth so the ground is being made up by the water in the line. Not the greatest situation in the world but in your case I wouldn't lose any sleep over it. The GFCI is you first line of protection.
The ground wire and neutral wire is usually joined back at the meter box on a common bar. Whatsup had it exactly right, because the neutral wire is carrying a load it has a slight potential compared to the ground due to the resistance in the wire itself.
 

wattsupdoc

Active Member
Correct that a GFI doesn't need a ground to work under most situations, say were a toaster gets dropped in the bathtub. But under circumstances where a normally submersible piece of equipment fails it very well may not properly work. This is the reason the ground rod is important used alongside the gfi. When only one side of the circuit becomes exposed top the water it may not trip the gfi if the path is not there. Having the ground rod and gfi insures that it will trip.
The ground wire and neutral wire is usually joined back at the meter box on a common bar. Whatsup had it exactly right, because the neutral wire is carrying a load it has a slight potential compared to the ground due to the resistance in the wire itself.
It is not that it has potential due to the resistance in the wire itself. It has potential because it is connected to the hot wire through the electrical equipment it operates. i.e. the light bulb. The ground wire is not connected to anything in the circuit other than things that have a potential to become energized.
 
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