As you know, I’ve been working with Allen Ruckle on the power upgrade to the
observatory area power panel. This panel supplies power to the Lipp and Cruzan
observatories, as well as all the private observatories.
Allen succeeded in obtaining the permit for the job, but we do have a challenge:
There was a change made to the code a few years back that would require we
install large enough cable or triple the number of conductors to keep the
voltage drop of that 750’ feeder run so that the voltage drop did not exceed 3%
of the breaker rating the cable is connected to. Based upon the 60 amp fuses
in the existing disconnect the existing 3/0 aluminum wire run could not be more
than 420 ft, or the over current device (Fuse or Breaker) at the main meter
location could not be more than 30 amps.
Allen spent about a half an hour describing how, over the past 45 years, the
number of people using the their observatories at once has been nowhere near
the rated capacity of the 60 amp 240v capacity of the disconnect. The
inspector decided to allow an exemption from that requirement as long as we
reduced the size of the Fuse or Breaker at the meter service location to 60 amp
2 pole 240v.
While discussing the possible remedies for the voltage drop with the Planning
department, he suggested we could reduce the voltage drop at the Observatory
area by installation of a 240 to 480v 15kva single phase step up transformer
and another one to step down the voltage at the service location. This would
cut the voltage drop in half. He said if we wanted to do that it would not
require a separate permit, but could be done under this permit.
This seems to be our best option. Before we do this, we need to run an
insulation test on that long 750 ft run from the main box the observatory
subpanel. If it’s not what it should be then we need to re-evaluate our
options, and those aren’t pretty. The cheapest would be to set another 100a
service at the North West corner of the observatory area and tie into the
existing observatory underground feeder that runs along the south side that all
the observatories are tied into.
Anyway, for the stepup/stepdown transformer upgrade we’re looking at the
following:
1. We will need a base to install these on. It could be a poured concrete
pad about 24” x 30” x 4” thick or a pre-cast concrete or high density plastic
equipment pad. I would guess the cost would vary depending on what we did.
Possibly a budget of 300.00 each.
2. 2 or 4 3’ flex conduit with wire and connectors.
3. 6 electrical lugs each for the connection to the transformers.
4. Quote for the transformers is $1,100.00 each for a total net price of $
2,200.00. Adding sales tax to the amount brings the total to $2,370.00. Lead
time is 30 to 45 days.
Just a reasonable guess for the above list I would guess it could run as much
as $ 3,000.00 for the transformers, pads and electrical materials.
Recommend the Board approve an increase to the amount we set aside for the
Cruzan electrical/subpanel upgrade by $4K just to be on the safe side. I’m
expecting it to come in a little less than that. All labor is free. Allen will
design and do much of the connections and whatnot, and I’ll do the heavy stuff
(digging, whatever).
Can we resolve this with an online vote? I’d like to get this moving.
Thanks!
Brian
