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I have been told I need second grounding rod. I am on well with plastic external pipes, however inside the house is copper. I have two boxes and one ground pole.The second box is grounded to the other box. I am trying to correct electrical shock in basement shower.
A 10 " driven ground rod is acceptable in many situations but we don'where you live or what your water table is like. Have you looked into what is causing the short?
All you need to do is drive another ground rod, no closer than six foot away from the existing rod, and connect with a copper wire sized accordingly to your service, and connect with a ground rod clamp at both rods.
Now that I explained that, why do you think that this is going to solve your problem with shocks in the shower?
I doubt that this will help at all.
How is the second box grounded to the first?
Is the inside copper water line bonded to the service? How?
Exactly where are the shocks being felt?
Any idea what the voltage is at this shock point?
You can drive and connect the second rod, and see where that gets you, and get back with more details as I am sure you will have more questions how to solve this problem.
Krussell; The voltage flucuates up to 12 volts. The second box is grounded with copper strain wire. The copper pipes are grounded to box with strain wire. The ground is also done with strain wire to the pole. The shower is in basement. Also get shock from outside faucet when ground is wet.
tkrussell;
I have been told by master electrican that wiring in house is OK. He believes there is nuetral problem in ground. Power company does not agree. They do both agree that it needs second ground pole for second box. Also, water is from well with plastic pipe outside house and copper pipe inside. Drain in shower is pvc. Get shock when water is running in shower and touching faucet and when ground is wet from outside faucet.
There is a serious issue with the neutral and ground. There are many possibilities, mostly caused by a loose connection, or more, at any one of a dozen or so connections.
And the grounding may not be proper, but adding a ground rod is not the sole solution.
The electrician should know how to troubleshoot the utility neutral, and review the entire grounding system for any defects.
If not, look for a good quality service electrician, one with the proper troubleshooting skills and instruments.
Without pictures, I doubt you can explain the extreme detail needed to help us point to any specific problems.
Sure sounds like a utility problem if the electrician checked the home.
Did anyone open the meter socket? That usually gets missed.
Tk russell;A picture of what would help? The 2 open boxes?
Yes, pictures will help us see what you have, open panels, grounding clamps or locations, at least a pic of the meter. Anything will help, as there are too many what ifs to go over, easier to see what you have and we can go from there, hopefully.
TkRussell;
Sorry it took so long to send picture. Thanks for your help.
Jackson,
Are both boxes fed from one meter? Is the water line bonded into the same panel as the ground line to the ground stake or is it in the other panel? Or is the ground stake connected out at the meter base only?
Are you familiar with working on ground wiring? There may be little or no voltage present but there can be enough current to kill you. Don't open any connections on ground wires without ADEQUATELY bypassing them first. And don't do this if you don't understand what I said.
Do you have a good DMM and are you comfortable testing around live equipment? I can give you a couple of tests to try, but I need to have answers to the other questions first.
EPMiller;
Both boxes are fed from one meter. Water is bonded into the left box and the ground stake is from the right box. I do not know what you mean by bypassing. I am comfortable testing live equipment. I have average DMM.
EACH service enclosure must be bonded to the water piping and also to a grounding electrode. The way yours is set up is not right.Quote:
Originally Posted by Jackson6112
Several NEC sections apply here: 250.58 is a main one. Many parts of Art. 250 II & III actually apply.
Are both main bonding jumpers installed (screw or strap bonding the neutral to the panel box)?
This graphic will give you an idea, although the notes do not apply here:
http://ecmweb.com/mag/507ecm1703.jpg
® Mike Holt
Jackson,Quote:
Originally Posted by Jackson6112
By 'bypassing' I mean establishing another alternate ground that will serve to keep the system grounded when you open up a connection that you see as questionable. You should NEVER break the grounding conductor or connections on a live system.
As to your DMM, what you need is one that will reliably read low VAC. What you should do is look closely at every connection in the grounding wiring and if you see anything suspicious, set the DMM to a low voltage AC range (400mV is nice if you have it) and check if there is any voltage across that connection. If there is an actual reading, not just the meter settling, then there is resistance there that is raising the impedance of the grounding system which will show up as voltage on the ground buss. Another thing I have done already is extend one of the leads of my DMM out to the ground stake and checked the resistance from the panel ground buss. Of course you have to take the added lead length into account. Check your meter reading with the long lead before you do that test setup. All this assumes that you are careful making good contact with your leads. A DMM is only 9 volts and can't do the job of a megger. You may or may not be able to find your problem with this method.
The shock that you are getting in the basement shower is the electricity from the mains that is finding an easier path to ground through you than through the electrical service ground system. If as you say the plumbing is grounded in one panel and the ground rod is out of the second panel you have several connections that could cause impedance trouble. Especially look at the connection where the ground system wiring is connected to the house water pipes.
Late addition: I forgot to say that when you do the voltage check on the ground connections, there must be current flowing in the conductor. You can check that if you have a clamp meter, but if you turn off every other ROW of single pole breakers in the panel you will be drawing current from only one leg of the service. If you turn on a bunch of lights and such, that should get you several amps to do your measurement.
Stanfortyman; There are 2 4strain wires going between each neutral/grounding bar in each box. Does this do it?
I do believe groundsin this case have to be a solid conductor. Stranded conductors are not permitted. Can someone confirm that?
I know that in my house, the water pipes are the grounding electrode. The pipes also pass underground. This was permitted back in the day. An allowed fix was to bond both side of the water meter if the water meter was plastic.
KeepitSimpleStupid; I have plastic pipes from well to holding tank. From holding tank on are copper.
That may fly for some inspectors but I would not do it that way. I guess it performs the same task in the end.Quote:
Originally Posted by Jackson6112
Can I assume you are referring to stranded wire when you say "4strain"?
KISS, unless there is a local amendment solid or stranded is fine.
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