[RFI] DirecTV to ground or not to ground

[Jim Brown]

On Wed, 24 Dec 2008 21:04:26 -0600, jvpoll at dallas.net wrote:

>b) History, practice and more importantly, mistakes in 
>practice (accidents) have made important contributions 
>to the NEC than simple theory would or  could predict;
>take for iinstance grounding practices. What _is_ the 
>rationale for grounding the secondary circuit (the 
>service to the home) of a power transformer for instance? 

>This isn't strictly neccessary for that service to 
>function. (I am asking this for the purposes of bringing 
>forth an example; I can cite cases where, in practice, this 
>has saved property and/or life, but that is different than 
>a statement or the treatment a textbook might give.)

>Could you cite a textbook wherein that rationale is brought 
>to light? 

One reference is the tutorial cited below. While it's written 
for sound and video contractors, the fundamentals apply to 
hams. 

http://audiosystemsgroup.com/SurgeXPowerGround.pdf

It all comes down to safety. The secondary is bonded to provide 
both lightning safety and, with the equipment (safety) ground 
conductor (green wire) provide a solid path to blow a fuse or 
breaker if a fault develops that could shock someone or start a 
fire. The lightning protection comes from because the bond to 
earth limits the potential that can exist in the event of a 
strike. The concept behind lightning protection is to have the 
whole building rise in potential by the same amount.

NEC can be purchased in annotated form -- that is, with 
explanations and commentaries interspersed with each paragraph.  

73,

Jim Brown K9YC