Temporary Power

[lookingforhelp]

Good morning everyone, I need some help for folks much smarter than myself.

I am working on planning a project at an industrial facility and was asked to evaluate their temp. power needs. They have set 10 blast resistant buildings they will need power supplied to. What I have a available is (2) temp power racks, each one has a 75 kva transformer and a distribution panel with a 225A main.
Any thoughts on if this is sufficient?

Thank you

 

[lookingforhelp]

Good morning everyone, I need some help for folks much smarter than myself.

I am working on planning a project at an industrial facility and was asked to evaluate their temp. power needs. They have set 10 blast resistant buildings they will need power supplied to. What I have a available is (2) temp power racks, each one has a 75 kva transformer and a distribution panel with a 225A main.
Any thoughts on if this is sufficient?

Thank you

I apologize, I didn't mention each building has a 150 A main breaker in the distribution panel

 

[zbang]

Size of the main doesn't matter much, what's the actual load for each building? If the total load of all buildings is only 40KVA, you're golden; if it's 200, you're not .

There are a lot of other considerations, of course- voltage and voltage drop, how the temp feed is going to connect in, distances, etc. (Is everything 3-phase?)

 

[petersonra]

As mentioned by another poster, you will need to first get an idea of how much power each of the buildings will need during the temporary phase. You are only allowed to use temporary power during the construction phase for the most part, so it may be that all you have to power is some lights, power tools, and maybe an air compressor.

But you may also have to contend with the need for a large amount of electric heat, which could seriously skew the amount of power needed.

 

[lookingforhelp]

The only equipment with the buildings are the AC units. As far as total loads it will be a best guess. 3 or 4 computers, coffee makers, refrigerator etc. in each building.

 

[zbang]

While those other things could be only 1-2kva, the AC units could be 1 or 20kva. Do these buildings already have power? That's not clear.

If you can assume that the total load per building is less than 15kva, then that'll work on the two 75kva transformers. Assuming the buildings have their own panels, you could probably feed each with a 2- or 3- 30amp breaker and be well within both demand and capacity. Only knowing the actual load will tell.

As mentioned above, there are certain rules for temporary power (article 590) that are somewhat relaxed from the regular wiring rules, but they're also time-limited and may not be appropriate for the environment- "blast resistant" implies an explosion or fire hazard, and may drive the acceptable wiring methods.