On Tue,2/3/2015 8:37 AM, N3AE wrote:
Interesting side note: 2011 NEC Article 810 says you have to have a "listed antenna discharge
unit" unless the coax shield is grounded. As far as I can tell, none of the common 50 Ohm coax
transient suppressors (Polyphaser, Alfa/Delta, I.C.E) are "listed." I've not seen a U.L.
sticker on any of them. Guess if you had a really finicky inspector he might get you on that. But
the Code gives you a way out by grounding the coax shield, which is good practice anyway.
Proper installation of a Polyphaser or other similar transient
suppressor REQUIRES that the suppressor be bonded to ground, which, of
course, ground the coax shield at that point. The proper installation
point for a suppressor is as close as practical to both ground and the
equipment that it protects. If the suppressor were installed, for
example, in an aircraft, the bonding point would be to the
chassis/shielding enclosure.
With a tower, good engineering practice calls for the coax shield to be
bonded to the tower at both top and bottom.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|