Rooftop mount of wireless anemometer without grounding?

[ejfudd]

I am looking to install my wireless transmitter/anemometer on my roof.  This will be the center of a peaked roof.  I would like to stay away from metal as much as possible as I do not see full compliant grounding as an option due to homeowner association rules and the ugly grounding wire.  :^)  So are there any fiberglass rooftop tripods out there?  Any code gurus care to criticize/comment on this possible setup?  Other materials are welcome as well...

Another possibility would be a metal tripod with a PVC mast...  Would the metal on this need to be grounded if it is ~ the same height as my hvac vent?

[Bushman]

Fiberglass/composite won't help you in a lightning strike.

[ejfudd]

Fiberglass/composite won't help you in a lightning strike.

Why not?  Isn't fiberglass simply glass fibers (insulator) within a resin (insulator) over a dry wood (insulator) base?  What part of fiberglass would conduct?

[dalecoy]

Often, when there is a lightning strike, it's raining and everything is wet.

What is your local requirement for

... full compliant grounding ...

[ejfudd]

Often, when there is a lightning strike, it's raining and everything is wet.

What is your local requirement for

... full compliant grounding ...

same as NEC.  But does this apply in the case of non-metallic rooftop items without wires going into/around the structure?  (wooden roof w/ asphalt shingles) I am unfamiliar with local building code, so would not know if there is anything saying the top most point must be grounded...

[dalecoy]

same as NEC.  But does this apply in the case of non-metallic rooftop items without wires going into/around the structure?  (wooden roof w/ asphalt shingles) I am unfamiliar with local building code, so would not know if there is anything saying the top most point must be grounded...

The NEC does not require lightning protection.

http://www.lightning.org/faq/what-does-national-electric-code-nec-say-about-lightning-protection-buildingsnbsp-it-only-requir

You haven't said where your "local" is, but most local codes do not require lightning protection for residential structures.

[Bushman]

Fiberglass/composite won't help you in a lightning strike.

Why not?  Isn't fiberglass simply glass fibers (insulator) within a resin (insulator) over a dry wood (insulator) base?  What part of fiberglass would conduct?

Fiberglass whip antenna on boats are hit regularly.  Who knows what lightning is thinking??  Regardless, the current will travel to the nearest metal; the glass conduit  is merely a vector.

[SLOweather]

And rain, dew and dust make the fiberglass conductive on the skin. We live across the canyon from some high voltage transmission lines. We can hear the crackle of the arcs across the big ceramic insulators, and sometimes, see them at night.

At lightning voltages, dang near everything will conduct, at least on the surface.

[d_l]

Grounding for an anemometer pole on your roof would be primarily to dissipate possible static charge build up which could travel down your anemometer wire to the Davis electronics (ISS or anemometer transmitter) if it isn't discharged.

[SlowModem]

And rain, dew and dust make the fiberglass conductive on the skin. We live across the canyon from some high voltage transmission lines. We can hear the crackle of the arcs across the big ceramic insulators, and sometimes, see them at night.

At lightning voltages, dang near everything will conduct, at least on the surface.

I have a 500kv line that runs across my property.  It crackles and pops all the time.  It is said that if you go out on a humid, damp, or foggy night and hold up a fluorescent light, that it will light up.  I've never tried it, though.

There's a big metal tower in my yard (you can see the base of it in my avatar).  I call it a monument to my employer, since I operate a powerhouse. 

[C5250]

The NEC does not require lightning protection.

True, NFPA has pretty much eliminated any mention of traditional structure lightning protection systems. But there are still some requirements, such as the grounding conductor of communications cables must be tied to the structure ground. Somewhat related to the OP's question is 810.15(2002). Which states "The antenna mast that supports radio, HAM, television and satellite receiving antennas must be grounded". It is debatable, if this would apply to a wireless transmitter, but I wouldn't want to put up a lightning attractor without proper grounding.

Note to OP, "same as NEC" is meaningless without stating which code cycle your AJU is using.

[dalecoy]

You can't "attract" lightning.

[Bushman]

You can't "attract" lightning.

Then what are lightning rods for?

[C5250]

Lightning rods don't "attract" lightning, they drain the static charge buildup that might attract lightning.

[SlowModem]

You can't "attract" lightning.

Tell that to Ben Franklin!   

[DanS]

And rain, dew and dust make the fiberglass conductive on the skin. We live across the canyon from some high voltage transmission lines. We can hear the crackle of the arcs across the big ceramic insulators, and sometimes, see them at night.

At lightning voltages, dang near everything will conduct, at least on the surface.

millions of volts aren't all that selective with what they strike. You "hit the nail on the head" with that explanation.

[dalecoy]

You can't "attract" lightning.

Tell that to Ben Franklin!   

Ben didn't attract lightning. 

[Aardvark]

you don't need to ground it , however, if it will take a load off your shoulders, let you sleep at night in a storm, then by all means do it.

A direct hit, nothing is going to save it and a nearby hit, will screw the transmitter a bit.    IF  I were to ground it, use a thick copper non insulated wire with a good set of stand off insulators and a six foot grounding rod .

I would recommend going either to a HAM radio center or to an electrical company for the parts.