[TowerTalk] Obstruction Lighting

[Jim Lux]

A
> > The next decision isn't quite as easy to make. I can use a standard 110
> > VAC
> > light that costs about $120 or a 12 VDC light that costs $223 (Dialight
> > model 860-1R03-001 from www.unimar.com). Either option only requires a
> > couple of amps.
>
>Even with a couple of amps at 12 volts you wouldn't want to go far.
>
> >
> > I will have mast mounted preamps for 6m, 2m, and 70cm mounted at the top
> > of
> > the tower, so I need 12 VDC there anyway. I could run 110 VAC to a NEMA
> > box
>
>You are probably going to want the 12 volt supply up there any way which
>means running the 110VAC  up there as well.

Just because it's low voltage doesn't necessarily mean you don't need 
permits etc.  The low voltage thing in the code is for energy limited 
systems (doorbells, garden lights, etc.) that have current limited 
transformers.  The voltage is limited to <50 V (shock hazard), but the 
energy is also limited (no fires possible).  You'll see this described as 
"Class II" wiring.

I would imagine that running 100 Amps at 12V would raise the local 
electrical inspector's eyebrows.

Something else to consider is that if you run both 110V and 12V, they'll 
have to be in separate raceways (conduits), except in certain circumstances.

What you might contemplate is not wiring your tower as an electrical 
system.  That is, have the electrical service terminate at a GFI receptacle 
with appropriate overcurrent protection at the base.  Then, everything else 
on the tower (12V power supplies, lighting supplies, etc.) is "installed 
equipment" all connected with a flexible cord and plug.  I'm not sure 
exactly how you'd want to present this, and it may be fundamentally 
incompatible with the FAA's need to have reliable obstruction lighting.