Electrical notes

I thought the distance was closer to 1900 feet; but, maybe not.

Moving the transformer closer to the theatre is feasible. I would also suggest that we make its pad big enough to place the Porta-Potty. (Maybe even with a drainage grate in front of its door.)

The service entrance size sound right.

(We currently have a 100 amp panel in the Hen House. It is fed though with a 60 amp breaker, at Toutle.)

We also need to be aware of easements. We would be crossing Foundation property.

I do not think that the sound system needs its own dedicated service.

I have a couple of other ideas.

We could have PSE place a pole and transformer near the trailhead. (Maybe make the pad big enough for that Porta-Potty.)

This scheme would also require the same transformer, in the same location, at the theatre.

We could utilize the spare (~ 700 foot) conduit that already runs from Toutle.

My second idea is to use the existing wire by using our own transformers (Yes, we would need to buy them.) to step the voltage up from 240 to 480 at the trailhead and back down to 120/240 at the theatre.

This may not give us the full 200 amp service capability; but, the theatre transformer will fix the problem with the neutral wire.

Our current problem, at the theatre, is that the voltage fluctuates with the load, due to the voltage drop in the neutral wire. We have sufficient ‘ampacity’.

-Greg Brown

Just another idea. I hear from the set people that they do not like to use their air compressors, at the theatre. This is due to the neutral problem. The heavy start-up load causes the motors to overheat and possibly burnout. Since air tools are commonly being used, maybe we should include an air compressor in this project.

If we specify that it be wired for 240 volt operation, it would by-pass the ‘neutral problem’.

-GB

The neutral problem is that when one side of the incoming power is heavily loaded (compressor, hair dryers, etc.) the voltage, on the other side changes; because of the drop in the neutral wire.

The transformer at the theatre solves that problem by locating the neutral closer to the theatre.(Shorter run, less voltage drop.) And yes, some of the problem is related to the length of the run. The transformer steps the voltage up at the trailhead so that the voltage drop becomes a smaller percentage of the losses in the run.

If you multiply the amps times the volts, you get VoltAmps (watts). Example 2000 VA @ 240 volts is 8.33 Amps. @ 600 Volts it is 3.33 Amps. The voltage drop, in the wire, is equal to the amps x the resistance. (If the resistance is, say, 2 ohms (for the trailhead run) then 2 x 6.3 Amp = 12.6 volts. (At 600 volts it would be 6.66 volts.) This is showing up in the neutral wire. (The run from Hansen’s would have similar losses. Because the run is approximately double, use 4 ohms in the above formulas.) (Note, the ohm values are just guesses, for illustrative purposes.) (Note also that as far as the electrons are concerned, the run is twice as long. 700 feet = 1400 feet, 1900 feet = 3800 feet.)

Whether we go from the trailhead or the Hansen’s, we would have a transformer at the theatre. The advantage of the trailhead is that the run is shorter; therefore, less voltage drop.

It just occurred to me that we may not need a transformer at the trailhead. The Hansen’s transformer is fed from a ’tap’ (2400 volt to 600 volt) on a pole mounted transformer. The voltage would come from the street to the pole at 2400 volts. The PSE transformer would step it down to 600 volts. That line would go to our conduit. -GB