Water is plastic and it's not worth the hassle to get at the rebar in the footing. Walls are block up to 24" above grade. So I'll be going copper rod at the power entrance.
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You are correct. Bear in mind, this is electrically speaking regarding a separate grounding conductor. The disconnecting means may be a primary switch box, or the subpanel with breakers and so forth. That is where they (grounding at separate building and introduced power) become all part of the buildings electrical system. I only count one grounding rod in this scenario. I don't know where others are coming up with another as well to be added.
You may be interested to know that UL says they test 15 amp receptacles for 20 amps feedthrough. The information is unfortunately missing from the UL directory I found on line, but see UL's response at the bottom of this thread:
Anytime a grounding rod is your only grounding electrode, unless you can prove that the resistance to ground is less than 25 ohms, you need to install a second ground rod. Since doing a proper ground resistance measurement is alot harder than driving a second ground rod, the only practical solution is to use two ground rods.
In my opinion, this "25 ohms" requirement is a bit of historical fluff without a rational basis, so the requirement should be rewritten to simply require two ground rods.
You can do lights in 12/2, it is just a little more trouble. Since you say the breakers you already have are 20 amps, it would save you the trouble of getting 15 amp breakers.
"Push-in" connectors on receptacles are only approved for #14 wire. I prefer spec grade receptacles with back-wire, screw-tightened pressure plates. As for pigtailing, I don't bother except where required (the EGC, and the neutral conductor on MWBCs).
Wayne Whitney wrote in news: snipped-for-privacy@silence.private:
If you do use 15A outlets on a 20A circuit, remember to pigtail them in. In other words, DO NOT place the 15A outlet so that it interrupts the circuit. Use short pieces of 12ga wire to pigtail the outlet across the uninterrupted 20A line. I believe any other way of wiring would be a code violation, just as if you wired part of the circuit with 14ga wire. In either case, you are putting something rated for less than breakered capacity into the circuit, and are asking for trouble. The design philosophy is that everything downstream of the breaker must be rated to at least the capacity of the breaker, if not higher. You are allowed to put a 15A outlet in with a pigtail, because you cannot draw more than 15A through it unless you've been mucking with the plugs. If you wire a 15A outlet into a 20A circuit using the standard 'screw in - screw out', then you have placed a 15A rated device into a 20A current path, which means that now that outlet is the least rated device in the circuit, and not the circuit breaker. Not a good idea.
*Thanks for posting that Wayne. That's the first official statement that I have seen that indicates that 15 amp receptacles have been tested for 20 amp circuits. Judging by all of the posts there has been a lot of confusion over this. It would be nice if the manufacturers just stated the approval on the packaging.
Got a bunch of lights to do as well so I'll need some 14/2 anyway. But the box I got was one of those "value packages" that came with 5
20 amp breakers so I might as well run 12/2 for all the outlets. You pigtail instead of using the push in connection to carry on? I can see that since I'm often finding poor connections using the push in.
"Ever just not cut the wire, instead strip a section and loop it on the screw terminals?"
*Yes I have done that and it would be considered a tap so it is acceptable. Stay away from using the spring loaded push-in terminals. Use a better grade of receptacle. Use GFI receptacles in the bathroom, garage, kitchenette and outdoors. By pigtailing, the full load of the circuit will not be passing through the receptacles which tends to make the first receptacle in line the weakest link.
So, let me get this straight. You're driving a solid 8' copper rod into the earth. It may be straight down, it may be at an angle or even approaching sideways. If any part of the earth is greater than 25 ohms, you have to use
2 grounding rods, not one. Y/N?
What about air voids in the driving rods scenario, are they a factor in the scenario of 2 grounding rods? If not, why not?
Are alll the other previous single grounding rod requirements from the former NEC grandfathered, or do I have to go out there and do another grounding rod for each one currently provided? If grandfathered, other than convenience sake, why?
Nevermind, you're just citing code without NEC code designation.
Saw nothing on "grandfathering" or air voids in the earth.
In one forum, I noticed some inspectors are making the declaration that 2 grounding rods are required, unless the installer can prove the less than 25 ohm requirement on one grounding rod. Not vice versa, that is, the inspector testing one and sole grounding rod and finding greater than 25 ohms megged, and then making the declaration that 2 grounding rods are required.
Since the earth is cumulatively resistant over distance/depth and varies with soil type, various stratas with that soil, and water content, I don't see how megging is of any way of any bearing. This is a farce, just make the 2 rod requirement and be done with it. Stupid code.
*I'm in NJ and it is currently accepted that there is no place in the state that you will find less than 25 ohms to earth with one ground rod. Consequently the two rods are installed.
Here it is up to the installer to provide the proof that something is acceptable. That's why I always save some labels and packaging until after a job is finalized. If an inspector questions me on something I have the documentation that the item is approved for the use.
You're right that the two rod requirement is a bit of joke. No one seems to know the origins of the 25 ohms. Ask an expert or call up the NFPA and ask them.
I don't recall ever seeing the NEC mentioning grandfathering. If that were so that could mean that every house would need to be upgraded every three years. The NEC is only a guide that can be adopted by states, counties and towns. Some jurisdictions adopt it as is. Others such as NJ adopt most of it, but leave exceptions to certain requirements. During the last code cycle we were not required to install arc fault circuit breakers and as far as I know they still are not required. It would be up to your local jurisdiction to require the upgrading of ground rods.
Regarding air voids in the earth. I have never heard any reference to this and I am not sure how you would determine that your rod passes through one. However an air void would affect the ohms to earth since there would be less earth contact. Another reason to have two rods.
Copper clad ground rods have a rated life of 40 years. Galvanized is much less. If your rod is old I would suggest that you put some new ones in.
I would bet the only time you will need to add the second ground rod, is if you pull another permit. You would then be required to be up to the current code.
No, the house and detached garage were finished at beginning of 2005. Detached garage, its electrical installation, its entireity, were built by myself. It was within NEC code at the time with one grounding rod. The only enforced building regulations here are for new septic installations. These regulations are county oriented and county enforced.
The air void thing is a question as my area has a lot of fractured limestone. The majority of which begins at the surface, no topsoil to speak of in some cases. In rock barring and digging this up for fence posts, I did find some air voids if I carefully dug without upsetting what's underneath.
Just curious. How does one connect a standard 2 cable megger, with spin handle for current, for testing resistivity for a grounding bar regarding the maximum 25 ohm requirement? How many samples have to be taken to establish the actual maximum resistivity for the NEC regulation?
That depends on the NEC code in force at the time it was built. The current NEC requires using the foundation rebar as a grounding electrode in new construction. I believe that requirement began with the 2005 NEC. Of course, your garage may have no rebar in its foundation.
You can't. If you use two ground rods far apart, and measure the resistance between them, you are getting the sum of the resistance to earth of the two rods. So for measuring resistance to earth on a single ground rod you typically use a special three point tester, which provides enough information to isolate out the resistance of each of the ground probes. Since the tester is fairly expensive, and the test fairly complicated, it is much simpler just to drive two ground rods and skip any measurements.
*My you have a lot of questions. Quite frankly I don't know. The ground testers that I have used were of the three point type and the clamp on type and were battery operated.
Many years ago I was a foreman on a shopping center being built in Burbank, Ca. The power company had very strict requirements for their transformer pad. They wanted less than 25 ohms and the soil was sandy. We had already installed two ground rods prior to the arrival of the tester from the power company, but I had a few more handy with clamps. When the guy did his first measurement he said it was no good. We drove a third rod and it was still no good. After the fourth rod he said it was close enough.
Try doing a search on the internet for instructions on using the meggar. Maybe try the manufacturer directly.
Incidentally the two rod requirement was in the 2005 code.
I had an extra ground rod concern (had one, needed an additional one) a while back. The inspector suggested use of a single ground plate (approx. 15" x 20") instead of the ground rod array. The plate was only 30" deep. This was in northern Ontario. I didn't see plates mentioned up-thread.
I had an extra ground rod concern (had one, needed an additional one) a while back. The inspector suggested use of a single ground plate (approx. 15" x 20") instead of the ground rod array. The plate was only 30" deep. This was in northern Ontario. I didn't see plates mentioned up-thread.
*The plate is certainly a viable and approved option.
The garage slab and driveway were constructed, poured, and finished by a company that normally does commercial slabs and county road needs. The garage has the standard rebar beam perimeter, remainder has bags with fill overlaid with rebar. I don't know the gauge of the rebar. The rebar was thicker in the beams than the remainder. The rebar in the remainder was thicker than that used in the driveway. They also went out of their way to put a miniature beams (not rebar reinforced vertically) on the driveway perimeter.
I went by the NEC available and approved at the time in the late 2004 era. As did the house builder. Both the house and detached garage have their own single grounding 8' bar (copper), #4 copper bare wire and copper crimp clamp.
Which explains why the inspector don't do such tests... They just enforce code, not establish if something meets code with testing. The 2 grounding bar is his out.
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