NEC "Tug Test"?

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This Occurred in Mckinney. Apologies for the late reply. Been crazy busy like the rest of us!
I wonder if that is the same guy in McKinney who failed us and made us add a ground rod to a roof mounted PV system in order to comply with the now removed and widely maligned Article 690.47(D). In all the jurisdictions we dealt with when it was still in the NEC, he was the only inspector who made us do that.
 
We recently completed a Generator installation, and the inspector was pulling on the Generator Feeders wires at the Automatic Transfer Switch until they broke loose. My onsite electrician told me that he tugged on them with both hands at the Transfer Switch until it broke loose at the terminal. He then failed the inspection stating that the wire lugs were too loose for the inspection. The inspector pulled on a Metallic Seal Tight Connection in a similar manner until that broke loose as well and then stated that the seal tight connection was also loose.
I've been thinking about this. I would consider this to be vandalism, and would sue for repair costs.

If the inspector is granted immunity by his department, then they would be next in line.

Try for an all-inclusive suit, where you get compensated, and let the defendants sort it out.

I wouldn't just let this go. I'm not made that way.
 
That is pretty nuts and out-of-line for McKinney. Irving seems to the one we are hearing and dealing with.

McKinney has been a little nuts on the submittals / plans docs for a while -- last year or so.

But there are so many bad planning / engineer drawing sets coming from (who knows) other parts of the world that are just mindless cut-and-paste it is a little bit understandable.

Actually glad your experience was not Irving. I have three projects there I need to sort out.

Only one open in McKinney, and they had a legit grounding issue with us. We moved the Main Disconnect outside, and needed to get the Grounds and Neutrals clear and clean downstream.
 
I wonder if that is the same guy in McKinney who failed us and made us add a ground rod to a roof mounted PV system in order to comply with the now removed and widely maligned Article 690.47(D). In all the jurisdictions we dealt with when it was still in the NEC, he was the only inspector who made us do that.
Grounds have become chaos with so many folks now doing combos and mixes of Existing + Solar + Batteries + Generators.

Mike Holt could a whole new cartoon series for just that.

"How to re-work a mess, without it becoming a bigger mess." (or some such)
 
There is a web site, boktscience.com, that goes over this in depth. Also the NASA fastener technical manual is quite good. Among other things it explains why you will find “helical spring washers” in a Grainger catalog but not “lock washers” (there is no such thing).
The standard way to provide a constant tension in a threaded fastener is the Bellville (cupped) washer. Used within their rating, they are quite robust and perdictable. There is no way to abuse them to destroy that force capabilty, but you can scrunch them down to provide higher than desired tension.
 
Grounds have become chaos with so many folks now doing combos and mixes of Existing + Solar + Batteries + Generators.

Mike Holt could a whole new cartoon series for just that.

"How to re-work a mess, without it becoming a bigger mess." (or some such)
Big Facts and some jurisdictions are requiring two earth rod grounds to be interconnected going back to the main disconnect. I spoke to another electrician a few months back and he told me that was actually nothing new under the sun but Im not finding that anywhere in the code book that requires two earth rod grounds for a home? I was always taught for a "super long" Grounding Conductor run that as long as your resistance was less than 25 Ohms an extra ground is not needed.
 
Big Facts and some jurisdictions are requiring two earth rod grounds to be interconnected going back to the main disconnect. I spoke to another electrician a few months back and he told me that was actually nothing new under the sun but Im not finding that anywhere in the code book that requires two earth rod grounds for a home? I was always taught for a "super long" Grounding Conductor run that as long as your resistance was less than 25 Ohms an extra ground is not needed.
The trick is proving 25 ohms or less. Generally cheaper and easier to just drive two rods.
 
I wonder if that is the same guy in McKinney who failed us and made us add a ground rod to a roof mounted PV system in order to comply with the now removed and widely maligned Article 690.47(D). In all the jurisdictions we dealt with when it was still in the NEC, he was the only inspector who made us do t

We were given a new inspector for the follow-up visit who was very pleasant to work with and very knowledgeable. He noted that we needed some more signage on the Meter Base, Inside Panel, and ATS. Basic signage that usually ships with certain Generator Brands that unfortunately wasn't shipped with this one. Ordering more signage stickers, placing them in the locations as requested by Inspector and he said we would be Green Tagged after signage additions. So Im happy that fiasco is done :)
 
If I checked Ground resistance from Earth Rod to Disconnect...Do you think that would be proof enough for an inspection?
You will need the right tester, a three or four point fall of potential set or a clamp type. By the time you tested it correctly you could have been done driving the second rod and been on your way home. The only time we bothered testing was if there was a performance issue or specification
 
If I checked Ground resistance from Earth Rod to Disconnect...Do you think that would be proof enough for an inspection?

Nope. That is not the Earth to rod resistance.

There are two meters on the market. The 3 wire fall of potential test is the cheapest meter but it takes about 15 minutes to do a test if you are experienced and has to be done without power.

There are really 4 tests with one meter. There is a two wire test that makes assumptions. Don’t do this…the three wire test is just as much time. There is the three wire test. And there is the four wire test that tells you ground rod resistance AND soil resistance.



The other one is a clamp on meter that takes a couple seconds. The downside is it does not work on a single isolated ground rod. In that situation I just use a temporary stake about about 50 feet of wire which takes a minute. The meter is fairly expensive but they are half of what they used to cost.


There are concerns that the clamp on is less accurate. The biggest problem I’ve seen with BOTH tests is user error. An idiot can screw either one up easily. With fall of potential you need the stakes in good soil and check your readings more than once as per instructions. With the clamp on make sure the clamp is fully closed and if you get an unusually high reading use a stake and jumper to check/verify that you have two grounds (the rod and enough bonding to provide a reference) if you get a screwy high reading, and be sure you are reading to the rod itself with unusually low readings.
 
You CANNOT INSPECT for torque after the fact, period. Once you torque TO SPEC that’s it. After that point the metal rapidly relaxes. 50-70% of loading us lost over the next couple weeks and a lot of it is lost in the first few minutes after you tighten. Haven’t you noticed that if you tighten everything first then go over it again it is still “loose”?

At best you can test calibration in the torque wrench. They are supposed to be checked every 1000 uses or so anyway.

There are dozens of ASME specs on this, and the NASA fastener technical manual.

NETA ATS (acceptance test standard) recommends torque testing (which is really an installation standard, not inspection), micro-ohm readings, or IR inspection. IR requires at least 25% load and energized. Micro-ohm varies by manufacturer but as a general rule all connections should be well under 1 milliohm. Unfortunately micro ohm meters cost thousands.

If it’s critical mechanical lugs should not be used. Use crimp lugs with dies that leave a mark. So the inspector can just look at the cable size, the die size, the crimp itself, number of crimps, the inspection hole if it has one to ensure it was fully inserted, and again torque but this time it’s a nut on a stud or bolt. This is the most reliable connection.
Now we need to put some kind of counter on the torque wrenches to tell us when to calibrate them?

Then comes the question of whether the counter needs calibrated periodically?

If the conductors were pulled on like in OP I'd say the termination likely does need re-torqueing after being subject to that even if it was torqued properly at install.
 
I can't believe not one person has commented that the inspector should go tug on himself instead of those conductors. LMAO Maybe it is just me with a warped mind.

Any "tug" by a human is subjective and therefore to me completely invalid. We do "pull tests" here at work on crimped terminals to validate our crimp tools and dies. It requires a crimped terminal to be placed into a machine and the wire to be connected to a head. The head will pull straight and constant until the crimp fails or the wire breaks. Force is recorded and there are min/max for pass/fail. This just grab it and jerk on it is nothing shy of ridiculous to me. Seems to me that re-torquing in front of the inspector and putting torque marks on it would be more valid.
About the only time I do a "pull test" is after using twist on connectors (wire nuts) to assure all the conductors were engaged in the connection.
 
I did a tug test today. Obvious overheating on a starter lug. Couldn't loosen it enough to get fresh conductor and barely tighten enough to make it work for awhile. Maybe. Sure could use those spare parts I got rid of 3 months ago.
Question is how long would you need to look through the spare parts to find what you needed?
 
Most jurisdictions give electrical inspectors full exemption from liability law suits, so the idea of suing the individual is out the window. At least in my state that is how it is. Not allowed to sue inspectors for liability. You probably can sue them for defamation or civil rights issues though if they violate those rights.
There can be exemptions for gross negligence that would allow you to directly sue the individual, otherwise as a general rule you go after the employer.

Liability exemption mostly so you can't sue them for passing something that did end up having issues, if they come on site and damage something that isn't what was intended with these exemptions, still might be something the legal system needs to sort out though and isn't exactly an automatic ruling.
 
What we really want is the compression force on the joint. Most of the “torque” we apply is just overcoming friction in the threads. Only 10-15% of the torque is applied to the joint. Plus torque wrenches are not as accurate as believed, And we can get into arguments about lubrication, surface roughness, corrosion, and so on but the fact is that tension accuracy just isn’t very good.

In electrical contacts the metal is not totally flat and it is covered in oxide. Squishing the joint cracks the oxide layer at the high spots forcing metal on metal contact called alpha spots. Further force smears the aloha spots so they grow in size as well as forming new ones but it’s a “diminishing returns” issue. The aloha spots are literally cold welds. So as force is removed we don’t uniformly lose contact…there is hysteresis. Less than 10% of the area if contact with bus bars actually makes contact.

One thing that this makes clear though is that if you aren’t mushing the copper so hard that it is highly distorted out of shape it’s not tight enough. Many times it bird nests so bad in the ends you have to cut it off and strip a fresh area to land it again.

Mechanically there is something called “dislocation theory” that shows that even though the metal crystals are solid at room temperature they will naturally relax and stress relieve themselves, permanentjy stretching the fastener. Just check for YouTube videos. The surface can also smear a little, allowing some loosening and what is called “fretting”.

Sure metallurgy plays a part, too. The stress/strain relations are different depending on the alloys but really we don’t care what is in the joint. We are torquing and stretching the bolt/screw/box. This puts tension in the electrical contact. The torque is on the steel or aluminum threads, not the copper. That is what the steel washers are for…keep the steel from digging in.

Fortunately this is all known. Electrical joints as far as I can tell are seriously over-rated and we know that because failures are not very often.

There is a web site, boktscience.com, that goes over this in depth. Also the NASA fastener technical manual is quite good. Among other things it explains why you will find “helical spring washers” in a Grainger catalog but not “lock washers” (there is no such thing).
is the website you referenced https://www.boltscience.com/ ?
because there doesn't seem to be a boktscience.com . . .
 
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