Rods

[kwired]

90.4 Enforcement. This Code is intended to be suitable
for mandatory application by governmental bodies that exercise
legal jurisdiction over electrical installations, including
signaling and communications systems, and for use by
insurance inspectors. The authority having jurisdiction for
enforcement of the Code has the responsibility for making
interpretations of the rules, for deciding on the approval of
equipment and materials, and for granting the special permission
contemplated in a number of the rules.

And generally the AHJ is not the inspector, the inspector is usually a representative of the AHJ, but there are some that seem to develop a God complex, and sometimes we need to go to supervisors to set them straight.

 

[iwire]

IMHO testing after the installation is the inspectors job.

That is some funny stuff.

90.4 Enforcement. This Code is intended to be suitable
for mandatory application by governmental bodies that exercise
legal jurisdiction over electrical installations, including
signaling and communications systems, and for use by
insurance inspectors. The authority having jurisdiction for
enforcement of the Code has the responsibility for making
interpretations of the rules, for deciding on the approval of
equipment and materials, and for granting the special permission
contemplated in a number of the rules.

What does a random section of the NEC have to do with who is responsible for performing the test? :?

 

[kwired]

I was not aware that proof was require in the code only that the contractor was to use the requirement.

IMHO testing after the installation is the inspectors job. Exactly why when guys came from KY where the inspector MADE them install two, they would as me how many that I wanted. After letting them know that it was not the code according to Mike, I explained that I had no way to test it so I would pass one or two properly installed rods. Same if they wanted to make the #6 continuous to the 2nd rod.

As I mentioned in earlier post, I think the main reason for the wording change a couple cycles ago was because the way it was written it kind of did make the inspector either have to test the electrode or trust the installer if he said it was 25 ohms or less. The way it is worded now the installer has to install a second rod unless he can prove the first rod is 25 ohms or less - the inspector doesn't need to test it, but can ask for documentation of the testing or ask to witness the testing.

 

[iwire]

As I mentioned in earlier post, I think the main reason for the wording change a couple cycles ago was because the way it was written it kind of did make the inspector either have to test the electrode or trust the installer if he said it was 25 ohms or less.

I am lost on this, here is the 2002 NEC, the oldest I have on pdf.

250.56 Resistance of Rod, Pipe, and Plate Electrodes. A
single electrode consisting of a rod, pipe, or plate that does
not have a resistance to ground of 25 ohms or less shall be
augmented by one additional electrode of any of the types
specified by 250.52(A)(2) through (A)(7). Where multiple
rod, pipe, or plate electrodes are installed to meet the requirements
of this section, they shall not be less than 1.8 m
(6 ft) apart.

What part of that makes it the inspectors job to test it?

 

[kwired]

I am lost on this, here is the 2002 NEC, the oldest I have on pdf.



What part of that makes it the inspectors job to test it?

I didn't say the inspector had to test it, I said he either had to test it or trust the installers word that it was compliant.

The way it was written before if an inspector wanted to tell you to drive a second rod you could challenge him and ask him to prove the first was over 25 ohms, now he may still find a way to make you drive that second rod including citing 90.4, but the way it is written now he doesn't have those extra hurdles, he can ask you to prove the single rod is 25 ohms or less or you will install a second rod.

 

[jxofaltrds]

I am lost on this, here is the 2002 NEC, the oldest I have on pdf.



What part of that makes it the inspectors job to test it?

My installation is my 'proof' that I claim that it is installed to code.

The inspector is allowed to inspect my work.

All I have to do is make the installation available (provide ladders, etc.) to him, show him an approved print (if applicable) and any/all manufactures installation paperwork.

His job to inspect. 110.3 Examination, Identification, Installation, and Use
of Equipment.

How do I 'prove' that I properly torqued a lug?

 

[kwired]

My installation is my 'proof' that I claim that it is installed to code.

The inspector is allowed to inspect my work.

All I have to do is make the installation available (provide ladders, etc.) to him, show him an approved print (if applicable) and any/all manufactures installation paperwork.

His job to inspect. 110.3 Examination, Identification, Installation, and Use
of Equipment.

How do I 'prove' that I properly torqued a lug?

I suppose you could video record the torquing - but we can then argue over whether the video is genuine video of the particular installation:roll:

Some areas there needs to be some trust or else the inspector needs to be there to witness the installation, and that is not funny, as there are some things (not necessarily electrical) where that is what is done for specific tasks. I remember a long time ago when wiring a gas station, the fire marshal division that inspects the tank and piping system had to be on site and witness something as it was done with their piping - been so long I don't remember exactly what it was though, I do remember it was a fiberglass piping system.

 

[iwire]

My installation is my 'proof' that I claim that it is installed to code.

No ones instillation proves the resistance of a rod.

How do I 'prove' that I properly torqued a lug?

Easy, the inspection department could require that they be there while you do the torquing.

Do you think it is also the inspectors job to do the performance testing in 230.95(C)?

 

[Canton]

And generally the AHJ is not the inspector, the inspector is usually a representative of the AHJ, but there are some that seem to develop a God complex, and sometimes we need to go to supervisors to set them straight.

LOL....I love declaring war on an inspector who wishes to write in a new code article as he inspects my work....:happyno:

 

[jxofaltrds]

No ones instillation proves the resistance of a rod.



Easy, the inspection department could require that they be there while you do the torquing.

Do you think it is also the inspectors job to do the performance testing in 230.95(C)?

Resistance doesn't required proof as does your 230.95(C) example.


Absolutely correct here:

(C) Performance Testing. The ground-fault protection
system shall be performance tested when first installed on
site. The test shall be conducted in accordance with instructions
that shall be provided with the equipment. A written
record of this test shall be made and shall be available to
the authority having jurisdiction.

Guess we could add 225.56 Inspections and Tests.

 

[mwm1752]

If you watch Mike Holt's Ground Resistance Testing(real world experiment) alot can be deduced -- The area is around his office and the soil conditions appear sandy/clay -- with 20' of 5/8" rod in the ground his current was .4 amps @ 120v = 300 ohms -- this is pretty decent soil conditions -- the best would be IMO wet sandy salty beach. There is plenty of information to conclude that lesser soil condition with rocky, dry soils will not achieve 25 ohms with a single driven rod - most residential use 1/2" & 8'. If a EC wants to prove me wrong and not install a 2nd rod then I will be more than cooperative to let him test.

 

[zog]

Originally Posted by winnie

However if that single ground rod is not 'good enough' by a fairly arbitrary and difficult to properly test metric, then a second ground rod is required.

They should add that to the code section. :thumbsup:
.

Yep, that is about the best wording I have seen yet on this topic. Well done Winnie!

 

[kwired]

If you watch Mike Holt's Ground Resistance Testing(real world experiment) alot can be deduced -- The area is around his office and the soil conditions appear sandy/clay -- with 20' of 5/8" rod in the ground his current was .4 amps @ 120v = 300 ohms -- this is pretty decent soil conditions -- the best would be IMO wet sandy salty beach. There is plenty of information to conclude that lesser soil condition with rocky, dry soils will not achieve 25 ohms with a single driven rod - most residential use 1/2" & 8'. If a EC wants to prove me wrong and not install a 2nd rod then I will be more than cooperative to let him test.

what kind of moisture levels in the soil? I would expect lower resistance then that in most instances, however if applying 120 volts would expect the soil around the rod to dry out some and then resistance would increase and current would drop.

 

[mwm1752]

what kind of moisture levels in the soil? I would expect lower resistance then that in most instances, however if applying 120 volts would expect the soil around the rod to dry out some and then resistance would increase and current would drop.

The testing done is simple in nature. Obviously, moisture, drainage, and density of soils are conditional. A wet rainy day mosy likely would decrease the resistance which is good as lighting often occurs. Testing with voltage to measure current flow for a short period(15 seconds) most likely would not change the resistance significantly. Now if his test had shown say 50 ohms at a single rod there might be a possibility of compliance to code in rain conditions. There's an experiment I may do at my residence -- test the rod that has been there for 35 years then soak the area overnight & retest.

 

[Dennis Alwon]

Of course it's true. Let's say you're actually able to get 25 ohms with two rods - still not even close to tripping a breaker. One rod at, say, 40 ohms is going to give you the same relative performance - that is, still not enough to trip a breaker.

Whether every house has one ground rod or two - won't matter much for doing what they're really for - giving utility and lightning lots of points for reference.

The one ground rod vs. two may arguably be the most arbitrary and meaningless requirement in the entire Code.

Tripping a breaker is not the function of a grounding electrode...

 

[jxofaltrds]

Tripping a breaker is not the function of a grounding electrode...

Do we have a top 10 of electrical misconceptions here?

This has to be #1 or 2.

 

[zog]

Tripping a breaker is not the function of a grounding electrode...

Not in low voltage systems anyways....

 

[Pharon]

Tripping a breaker is not the function of a grounding electrode...

I never said it was. In fact, I specifically stated its intended purpose in my second paragraph.

I only said that to emphasize that its true purpose is relatively meaningless with respect to whether you use one or two ground rods. In other words, the functionality is not meaningfully improved by adding a second rod.

I thought I made that abundantly clear in my several posts in this thread, but evidently I did not.

 

[Dennis Alwon]

I never said it was. In fact, I specifically stated its intended purpose in my second paragraph.

I only said that to emphasize that its true purpose is relatively meaningless with respect to whether you use one or two ground rods. In other words, the functionality is not meaningfully improved by adding a second rod.

I thought I made that abundantly clear in my several posts in this thread, but evidently I did not.

You did qualify your statement but it seemed mis leading with that statement in there so I wanted to clarify that was not the purpose. I assumed you knew that

 

[Randel Sink]

Ground Rod Installation - vertical or at an angle

Ground Rod Installation - vertical or at an angle

Is there any guidance on the installation of a ground rod? Should it be vertical (plumb) or can it be driven at an angle? If at an angle, what is appropriate? If there is solid rock say 3 or 4 feet below ground level, can the rod be driven at an angle to be completely buried in the dirt before contacting the solid rock... say at an angle some where between 30 and 60 degrees?