[TowerTalk] [Tower Talk] Ground wire

[Jim Lux]

Ken Young wrote:
> Article 310.4 does apply to the grounding conductor.  What website did
> you see that said different?  You wouldn't stand a chance at persuading
> the inspectors differently here.  They are "by the book, no exceptions".
> 
> 73, Kenny, AB4GG
> 

Several places.. see for instance

http://wwww.iaei.org/subscriber/magazine/07_a/johnston.html

or google "parallel grounding conductor 310" and you'll get a bunch of hits.

For instance, maybe you've got parallel conduit(raceway) runs, and 
you're using the conduit as the grounding conductor.

Table 250.122 gives the minimum sizing, based on the overcurrent 
protection.

Whether 250.122(f) is applicable to the bonding conductors we're talking 
about is another question, but at least it's an example of legal 
parallel conductors smaller than 1/0.


There's also the whole issue of a conductor being used to provide 
grounding (viz Art 800) for, e.g. an antenna mast, as opposed to the 
electrical safety ground for a piece of equipment or a receptacle (Art 
250 stuff).  In the latter case, the conductor has to be sized to carry 
the max fault current in the event of a line/case short.  In the former 
case, that's not necessarily the motivation (in fact, given that they 
allow AWG 17(!) copper clad steel, I suspect that ANY conductor with 
sufficient mechanical strength is what they're shooting for)


it's an interesting question.