My AC ground is attached to my copper plumbing system.
I need to put a ground bonding jumper across a yellow brass ball valve that is in the system.
What size should that wire be? As far as I can tell it is supposed to be sized according to "Table 250.66" but I cannot find a copy of the NEC or of that table online anywhere or at our local library.
Anyone know the right answer off-hand?
Would a 6 or 4 gage solid copper ground wire be big enough for a bonding jumper (it's a 200 amp service)?
That woluld be a #4
73 from the Desert SW!!
Maybe this is a chance for a little more education on my part. #This is not a troll/smarty question.
If the brass ball valve has a continueous body, would not that be conductive enough to work for the AC ground? #I would THINK that a jumper would only be needed if the valve was constructed in such a way that there was not metal to metal contact between the two sides of the valve. #In other words, is there any problem with a copper-to-brass-to-copper connection for this application?
Please tell me if I am incorrect, and I would appreciate some explanation if possible.
EDIT: (removed "edit" it was redundant).
that is entirely dependant on wether the valve body is metal or plastic, if it's metal a jumper isn't needed, if it's plastic I'd run with the #4
Freedom isn't free, it carries with it the highest cost known to humankind, always has, always will.
I had to have my water service replaced and a new shut-off valve installed at the entry point to the house. The county inspector is coming in the morning to inspect and approve the work.
In chatting with the plumber he told me that the county inspectors do not consider ball valves made of yellow brass bodies to be "conductive enough" when the water pipe system is the electrical ground, and that the county inspector will probably say that jumper should be installed. So the plumber is bringing clamps and a jumper for the new shutoff valve in the morning, to install before the inspector comes.
BUT, I also have another shutoff valve - the same type of valve - that I installed some time ago myself, that is between the electrical panel and the water service entry point, that is not jumpered.
I've heard of having to use a jumper across water meters before, because there's often nonconductive gaskets or connections on them, #but I've never heard of having to jumper a valve. But this plumber seemed otherwise pretty knowledgeable and experienced.
Whether this is in the national electrical code, or just some arcane local nit-pick, I don't know. #
In any case, if the inspector starts nosing around (it depends on the inspector but basically they are allowed to nose around and look for "violations" if they are already in your house) and finds that other valve, then rather than risk getting nailed for that and having to take more time off work to deal with it, I'll drop by Lowes tonight and get the #4 wire and some clamps, and install a jumper. I figure it can't hurt.
I already do have half a dozen ground rods driven in the ground around the back yard, all bonded together with buried #6 or #4 bare copper, associated with my antenna systems and attempts at lightning protection. That is all bonded to my plumbing, of course, so I am not worried about the safety of my ground system. But rather than have to explain all that to an inspector (and potentially have to dig things up to show him), I'd rather just keep it simple and jumper the valve, and not mention the rest of my ground system.
I have intended to add a ground rod or two on the side of the house at the electrical panel, and connect that for the main electrical ground instead of the water pipes, but I just haven't gotten around to it yet.
A big question is if those valves are threaded joints or sweat soldered in place? # If threaded, I would install the jumper wires for sure. (threaded pipe joints often use "pipe dope" or teflon tape to help seal leakage that could cause a very high resistance) #If sweat soldered pipe joints, The jumpers will be mostly to calm your local inspector. #I too would install at least one copperclad rod near your service entrance to bond to the rest of your ground system.
They're both sweated joints, not threaded. I agree that if they were threaded, there should be a jumper for the reason you mention.
Well, the plumber is a plumber, not an electrician. Maybe he had an experience in the past being told to put a jumper on a threaded valve but wasn't clear on why and assumed it was any valve of that type. I'm curious now so I'll ask him about it this morning.
I picked up an 8 foot rod and a clamp while I was at it, and will add that to the system near the electrical panel this weekend.
I don't think this has anything to do with the conductivity of different metals or whether or not there are any gaskets involved, generally even if there are gaskets on your water meter, there are at least 2 bolts at each end that will connect the sections electrically. I'm an electrical contractor and as far as I know, the MAIN issue here is a personnel safety concern. You are required to place a bonding jumper across any device that may have to be removed for maintenance or replacement.
If the valve, or water meter are removed from the pipe, the electrical connection between the house plumbing and the "street side" of the water main will be broken. If there is a fault in the electrical system causing the neutral connection to be made through your water main, and then the water main is disconnected to replace a water meter (or valve) the person removing the device could be injured or killed if they are touching both sides of the pipe with the device removed.
If you run your ground wire from the electrical panel to the street side of the water meter, you don't need to have bonding jumpers.
Good luck, be safe.
Tom Green / W1SDM
Tom Green / W1SDM
Don't anthropomorphize computers, they hate it when you do that...
Actually the water meter is way out at the street in a concrete pit. There is no water meter in the house. So everything in the house as well as the 65 feet or so of copper tubing underground is continuous tubing except for a few sweated copper elbows and the two sweated valves. # The ground of the electrical circuit breaker panel is connected to the plumbing via about a ten foot length of bare heavy stranded copper cable, very heavy gage - probably 0 gage or heavier.
Originally Posted by [b
Thank you for the info. There is usually a logical explanation if one can find the person with the knowledge. I didn't think of loosing the connection if the part is removed for service.
I am guessing that the jumper would need to be long enough to allow easy removal of the part without being tempted to remove the jumper also.
Are there any requirements on how long the jumper needs to be, either mandatory or guidelines?