Yes, we need to see this through.
Dave D
On 1/18/2019 09:02, Brian McFarland wrote:
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
