guest

What is a "check-in shack"?

Assumptions.

1] The shack is already setup to be connected to a 3 phase supply.

2] I will also assume that "less than 25kVA" means close to but not exceeding 25kVA.

3] The existing 3 phase supply comes from a normal power distribution grid.

If you want to feed this shack (based on my assumptions) with a 1 phase supply, add the 3 lots of 25kVA together & this will be the required capacity of the 1 phase supply (75kVA).

If your existing 3 phase supply is capable of delivering 75kVA per phase, simply use one of these phases & a neutral.

Unless you provide more detailed info, I can't be of further help.

1. The shack is running off 3 phase right now, but that line will be terminated and the closest active line is 3 phase.

2. You are correct it does not exceed 25kVA.

3. Yes

I have no idea why three phase was even used to supply a shack with a small refrigerated hvac unit and some lighting.

First check if you actually HAVE any three phase loads in the check-in shack, as a three-phase supply may have just been conveniently available at the time. If you don't (and are not expecting any three phase loads in the future), then you can use a single phase supply.

Assuming that the current configuration is a wye-connected feed, all loads are single-phase, and the single-phase loads are connected between the neutral and one of the three phases (or between two phases with neutral / ground - possibly the case for an air conditioner as in a US 240VAC connection), then you would disconnect the bus bar at the panel that corresponds to the phase being removed. That bus bar could be connected to another phase bus bar provided that it isn't one of the feeds for a load between two phases, or its breakers and loads transferred to the remaining two buses. In the "two-phase" load connection case, the dual breaker would have to be powered from the remaining buses.

Moving the breakers to the two remaining bus bars may be a bit more work, but it would be cheaper than trying to jumper buses together and more likely to meet the approval of the electrical inspector. You may be required to replace the three phase main breaker with a two pole unit, but I think you could argue that if the input feed is disconnected and nothing is connected to the output of the abandoned phase, replacement would not be necessary. The first question is whether the remaining two phase panel and feed wires can handle the 25 kVA load.