[TowerTalk] Cadweld vs clamps

[Bryan Fields]

On 10/23/14, 11:38 PM, Bill Turner wrote:
> On Thu, 23 Oct 2014 17:51:16 -0700, Jim Lux wrote:
> 
>> >
>> >And from a electrical code standpoint.. a low-medium voltage feeder at 
>> >4kV falling on your antenna or tower will probably be held off by the 
>> >corrosion, or the wrap of tape, or whatever, and the whole thing will be 
>> >live.
> REPLY:
> 
> If the above were true, the NEC would mandate exothermic bonding
> instead of clamps. They don't. Clamps work. 
> 
> A lot of old wives' tales floating around here. 

>From TIA-607-B, Generic Telecommunications Bonding and Grounding (Earthing)
for Customer Premises


B.2.3 Bonding connections
Bonding connections are made by means of exothermic welding or Listed
irreversible compression connectors or mechanical connectors.

Exothermic welding is a method of making permanent welded electrical
connections without external power, such as electricity or gas. It is an
exothermic chemical reaction (exothermic means to release heat). The
temperature of the molten metal created during the reaction is sufficient to
fuse the metal of the conductors, resulting in a welded molecular bond.
Exothermic welding can be used to produce welded connections of copper to
copper and copper to steel. The advantage of exothermic connections over
compression and mechanical connections is that exothermic connections produce
a molecular bond with all the strands of the conductors, while compression or
mechanical connectors do not. All underground connections are made following
manufacturer recommendations with the exothermic welding process that use the
proper mold and weld metal materials.

A Listed irreversible compression connection is made by using specific
fittings and a high tonnage compression tool. These connections are considered
maintenance free; however they are not when used underground. When making a
Listed irreversible compression connection, all surfaces must be
properly cleaned and the components properly sized for the conductors being
bonded.

Mechanical connections are only to be used above ground and in areas where it
is impractical to use either an exothermic or irreversible high compression
connection. When making a mechanical connection, all surfaces must be properly
cleaned and the components tighten to the correct torque rating of the
hardware. Additionally, the correct material is used so as not to form a
galvanic couple.

-- 
Bryan Fields

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