Exothermic welding vs listed pressure connectors

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xoxota

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Electrical plan check for a particular city requires that underground grounding taps be made using the exothermic welding process exclusively.
The 2002 NEC, article 250.8 and 250.70 both states that the exothermic welding process is one of many ways in which to connect ground conductors and bonding jumpers. Our usuall method of connecting ground wires is to use a Burndy type YGHC-C Hytap connector (UL listed for for direct burial and concrete application).
The AHJ says that after 10 years or so, when the contaminated ground (petroleum refinery environment) has had a chance to work on corrosion of the bare copper ground wire, the pressure connectors will loosen causing a bad connection in the grounding system.
Any thought? .

What recource does an engineer have to argue the point with the preferences of the AHJ???

Thanks
 
Weighing one connection against the other, my guess is that melting something into a homogeneous mass is better than a pressure connector. Having said that, I don't think can the AHJ decide what type of connection is used based in his personal preference. He has to enforce the code as written and adopted by his jurisdiction.
 
Quote:
Originally Posted by xoxota
...The AHJ says that after 10 years or so, when the contaminated ground (petroleum refinery environment) has had a chance to work on corrosion of the bare copper ground wire, the pressure connectors will loosen causing a bad connection in the grounding system.
Any thought?
...

The technical term for that is scata taurus. If there is a written local policy adopted by the AHJ there's not much you can do about it but comply. If it is only an inspector's preference, there is probably an appeal process.
__________________
 
xoxota said:
Electrical plan check for a particular city requires that underground grounding taps be made using the exothermic welding process exclusively.
Click to expand...

I think that says it all. I will only use exothermic in my projects, but I work in telecom and it is a standard for all direct buried and concrete encased connections
 
I have worked with exothemic welding ( Cadwelding ) on some decent sized projects, I don't have a problem with using them versus pressure connections but I could only guess the the price per connection would "cost many times" more than a pressure connection would just by the materials , molds , proper training and good working conditions to have the connections worth anything.
Are all your connections tested ??
 
Does that 5 ohm really happen ??
Don't soil conditions play a big part in that .

I have worked under them same requirements and the 5 ohms was impossible to achieve.
 
For the initial installation, we always achieve the 5 ohms. The water table is not too deep. Sometimes we have to install 3 to 4 ground rods deep.
 
Are you doing your own testing?

I have never done the testing , just been on the install end.

Soil conditions play a big part in this does it not ?

You keep pounding grounding rods in till you get the reading you want ?

I have seen them put in 50ft and still the 5 ohms would not happen.
 
drg said:
Does that 5 ohm really happen ??
Don't soil conditions play a big part in that .

I have worked under them same requirements and the 5 ohms was impossible to achieve.
Click to expand...

I've achieved it many times. A #2 ground ring with 3/4" X 10' copper clad ground rods every 8-10 feet with the ring encased in bentonite. Or just install an XIT? ground rod. Those usually pulled the close ones in compliance easily.
 
I would guess that my last question does not matter .

You used this bentonite to achieve your requirements because soil conditions do play a big part in the results of the readings.

Thanks
 
drg said:
I would guess that my last question does not matter .

You used this bentonite to achieve your requirements because soil conditions do play a big part in the results of the readings.

Thanks
Click to expand...

Yes the soil conditions do make a difference. The bentonite holds the water in and also allows better conductivity to the soil.
 
xoxota said:
DRG
All connections are tested. Resistance to ground shall not exceed 5 ohms.
Click to expand...
That is not a connection test. A connection test would be done with a DLRO and a spec would be shall be less than 15-microhms.

5-ohms per connection would be awful. The 5-ohms is an overall impedance of the GES to earth.
 
On the job where we first used this equipment none of us had any training , the molds were junk and we wound up tearing out every connection we made, there were well over a hundred of them , maybe even hundreds I am not sure anymores.
Like I said we were not involved in the testing but I now on the re-do of the disater every connection was tested and "tagged OK" before we could bury again.
I will agree that this testing was different from the other ground testing and was only required because the original welds were so bad they did not trust us.
After recieving minimal training and brand new molds the welds really went together real good, at the time we were just put in a spot and handed a project where someone thought they could get away with something, nothing was gotten away though and they paided in spades for the rework.
 
Gentlemen
I have compiled several documents relating to this predicament. Some of the documents included are:
Burndy?s test report done for the specific connector we intend to use
An independent report done by Ontario Hydro Technologies on IEEE 837 test series
IEEE 837, Standard for Qualifying Permanent Connections Used in Substation Grounding
A copy of this thread
With this information I feel very good about the task at hand. I will keep you informed about the results.
Thank you for all your inputs.
Rod
 
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