[TowerTalk] Cadweld vs clamps

[Jim Lux]

On 10/23/14, 11:34 AM, Bill Turner wrote:
> ------------ ORIGINAL MESSAGE ------------(may be snipped)
>
> On Wed, 22 Oct 2014 21:19:50 -0700, David Gilbert wrote:
>
>>
>> What is it you want to know that hasn't already been explained for
>> you?   You either buy the technical explanations or you don't, and if
>> you don't accept them, why would you expect any other comment to change
>> your mind?  Anything else is just going to be conjecture.
>>
>> Dave   AB7E
>
> REPLY:
>
> Good question. The answer is that if Cadweld is so superior, why is in
> not mandatory in the NEC? Why are ground clamps allowed at all?  They
> are a very conservative organization and surely would err on the side
> of safety.



Listed compression fittings are allowed
Wedge locked fittings are allowed
(generically, "connectors listed as grounding and bonding equipment")

Clamps are allowed, with periodic inspection to insure that they are 
still tight.

250.68 A All mechanical elements used to terminate a grounding electrode 
conductor or bonding jumper to a grounding electrode shall be accessible.
Exception No. 1: An encased or buried connection to a concrete-encased, 
driven, or buried grounding electrode shall not be required to be 
accessible.

Exception No. 2: Exothermic or irreversible compression connections used 
at terminations, together with the mechanical means used to attach such 
terminations to fireproofed structural metal whether or not the 
mechanical means is reversible, shall not be required to be accessible.

250.70 Methods of Grounding and Bonding Conductor Connection to Electrodes.
The grounding or bonding conductor shall be connected to the grounding 
electrode by exothermic welding, listed lugs, listed pressure 
connectors, listed clamps, or other listed means. Connections depending 
on solder shall not be used. Ground clamps shall be listed for the 
materials of the grounding electrode and the grounding electrode 
conductor and, where used on pipe, rod, or other buried electrodes, 
shall also be listed for direct soil burial or concrete encasement. Not 
more than one conductor shall be connected to the grounding electrode by 
a single clamp or fitting unless the clamp or fitting is listed for 
multiple conductors. One of the following methods shall be used:

     A pipe fitting, pipe plug, or other approved device screwed into a 
pipe or pipe fitting

     A listed bolted clamp of cast bronze or brass, or plain or 
malleable iron

     For indoor communications purposes only, a listed sheet metal 
strap-type ground clamp having a rigid metal base that seats on the 
electrode and having a strap of such material and dimensions that it is 
not likely to stretch during or after installation

     An equally substantial approved means



I don't believe clamps are allowed in a buried application (you'd need 
inspection wells, and then the clamp isn't actually buried).