[TowerTalk] UL listed protector for ladder line

[Jim Lux]

Just checked the Polyphaser page - none of their antenna products are listed.  They *could* make one for you and get it certified. (as someone in the thread noted, this would be expensive).

I've not looked at this recently, but as I recall, the code requirement for an "antenna discharge unit" doesn't apply if the antenna conductors are completely contained within a metallic shield.  And Coax does that.  So you could run two parallel coaxes. With 75 ohm coax, that would give you a 150 ohm balanced line.  There's 92 ohm coax out there, too, which gets you 184 ohms.

You probably could find a listed 300 ohm balanced ADU - back in twinlead days - Channel Master made one - someone's selling it on eBay The model 9050 says UL listed right on it.

https://www.ebay.com/itm/264269502441

Is ChannelMaster even in business?

Or, you just transition from balanced line to coax at the point of entry. Typically, you want balanced line so that it's low loss with a large mismatch or the antenna is intrinsically high Z - if the coax run is short, maybe this isn't an issue.
 


On Fri, 13 Jun 2025 11:59:06 -0400, "Jim Lux" <jim at luxfamily.com> wrote:

UL listed coax protectors are none-to-common either (well, for cable TV, they're pretty common).

It depends on why Martin needs this.  Typically the requirement (e.g. from the county building dept) is "nationally recognized test lab" (of which UL is one) or "signed off by a licensed Professional Engineer". 

if they're being VERY persnickety, using two listed coax devices might not work, because "use as specified by mfr" is almost always part of the rules.  So you're back to finding a PE to design and sign off on an assembly.

Also is it "overvoltage protection" or "grounding" that is the concern - for satellite TV and Cable TV, it's "grounding of the shield" that's the concern.
 
What frequencies? 
What Z?
What specifically is sought by the AHJ here? Overvoltage and/or transient? 

On Fri, 13 Jun 2025 13:29:21 +0000, john simmons  wrote:

Would it fly to use two UL-listed coaxial lightning protectors? I doubt you'll find what you are looking for.

-John
On 6/13/2025 5:54 AM, Martin A Flynn wrote:

Have a situation where a UL listed protector is required on a ladder line feeder.

I’m striking out in my search

Any suggestions?

73 Martin

W2RWJ
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