Western Weather Service installer unsure whether NEC Code requires Panel, need help

[Installer]

I install Weather Equipment, often in the middle of nowhere out here in the West.
Usually at our Weather sites, the Service Feed comes from a small 208/ 120V 100A transformer the local Utility has installed on a Pad along with a Meter and we take it from there at the Meter Base.

Usually we put in a 100A Fused Disconnect Switch, a 100 A NEMA 4R Panel with 20 circuit breakers and a TVSS and feed 5 to7 Weather sensors (Wind, Visibility, Cloud, Freezing Rain,….) from that .Its all in accordance with the NEC Code


I’m now at a site where all we have is One Wind Sensor and a LED navigation Light.
The Service is actually one 20A breaker on a 100A panel 600 feet away at a small school building. The conductors run through an old underground conduit and are 8AWG.
The conduit is pretty long and old. I don’t think I have the tools to pull new conductors. Even if I pulled new ones, it wouldn’t do much good since I only have one 20A breaker upstream.


At the site, I would put in a a 40A DoubleTapped Disconnect Switch fused at 20A, since we have 8AWG conductors and a TVSS, but what do I do for a Panel?
I can’t find one that small meets our standards
Can I substitute two individual 20A molded case Circuit breakers and not use a Panel and still meet NEC Code? (The load on each of the breakers is only 5 or 6A, but we can’t use breakers that small.)
Each of the 2 Individual Molded Case breakers would come from the 40A Double tapped disconnect
That meets requirements We just need to feed the Wind Sensor electronics and a LED Light.

I’m worried that somehow I might not meet the NEC Code. because I’m using two individual molded case breakers instead of a Panel.

Is my proposal okay?

 

[zbang]

What's the actual load? Sounds like it's under 10A, so why not consider the 20A run from the school building a branch circuit and call it done? No need for a separate panel/breakers at all. Or, just install the same panel as usual but feed it with only 20A; a bit expensive, and quite overkill, but it would work. (There must be a smaller 4R panel available, but I haven't checked.)

My bigger concern is whether there is a good grounding conductor; are there three usable conductors or did the original install depend on the conduit as the EGC?

Interesting stuff.

 

[Installer]

Perhaps technically it is a Branch Circuit.
Unfortunately, because of the long 600' run from the School to the Wind sensor, there is a requirement for a Local Disconnect.
The Local Disconnect is required because the School Building is not in use and is locked and we can't get access to the upstream Panel at all times.
I don't understand the NEC Code well enough to see how it rules when the Service is other than a Utility.
Because the equipment is outdoors in a Lightning Zone, we have to install a TVSS at the Disconnect.
I'm guessing that the Local Disconnect and TVSS and the 600' run might cause interpretation of this as a Service.

As for grounding , I appreciate your feedback. We have one Ground Rod out there, but we'll put in three more and set up a Counterpoise.

 

[Installer]

The 600' underground run in the conduit might cause interpretation as a Service.

 

[wwhitney]

If there's the a breaker in the school building that protects this circuit, it is definitely a branch circuit. The length of 600' and the use of underground conduit are immaterial, it is not a service.

For a disconnect on a 20 amp branch circuit, you can use a simple 20 amp snap switch.

The concern about the grounding conductor has nothing whatsoever to do with ground rods. Ground rods are not required at the load end of a branch circuit, and installing a counterpoise (I assume an arrangement of multiple ground rods) is useless for electrical safety. Having an intact grounding (bonding) conductor is important for electrical safety.

So the question is whether your existing conduit run has a separate grounding conductor wire? I.e. a green wire? If it doesn't, then the original install relied on the metal conduit run to provide the proper bonding, and it is reasonable to question whether that buried metal conduit is still in good condition.

Cheers, Wayne

 

[Installer]

Thanks! There is no green grounding conductor! The conduit is old and it could have rusted out. We may have to check it with a Resistance Tester. If its failed, then I have to write it up.