Need Help Figuring out Site Temp Power

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KD4315

Member
Hello All,
I'm bidding a project that has 3 buildings. A Maintenance Building, Laboratory, and Office Building. I need to figure out what to put in for temp site power. I've never had to figure this out before. Where should I start?
 

John120/240

Senior Member
Location
Olathe, Kansas
How close are they to each other ? What direction is the POCO distribution ? Will you have one main gear in the first building then

feed the other two ? Others will chime in
 

iwire

Moderator
Staff member
Location
Massachusetts
To add to Johns questions

How big are the buildings

Is the schedule aggressive with large crews or laid back with few workers?


You really want to plan ahead so that you do not have to keep relocating the equipment.
 

KD4315

Member
How close are they to each other ? What direction is the POCO distribution ? Will you have one main gear in the first building then

feed the other two ? Others will chime in

The buildings are laid out in a sort of triangle and are 100-500' away depending on where you measure from. There will be a 3000A Substation and then each building has is own distribution board. The Maintenance Bldg is 1600A the Lab is 1200A and I think the office is 800A. I can't remember off the top of my head. I'm not sure what you mean by what direction is the POCO distribution.
 

KD4315

Member
To add to Johns questions

How big are the buildings

Is the schedule aggressive with large crews or laid back with few workers?


You really want to plan ahead so that you do not have to keep relocating the equipment.

I guess you can call it an aggressive schedule. All 3 buildings will be constructed at the same time so we will have to provide temp power to all 3 simultaneously. The buildings are big. The Maintenance Building is 40K square feet. 2 floors @ 20K each. The Lab is 10K sq feet and the office is around 30K sqft. 3 floors @ 10K sqft.
 

cadpoint

Senior Member
Location
Durham, NC
Some things to consider.

What size is each building, I'm sure there is various ceiling heights, and possible multi floors. Metal halide might be considered. Their light about one every thirty feet at 15' covers a lot of ground. Just count up the amps required per light and built a circuit with 125% in mind.

Hopefully you have the minimum of 208/120 to site, set the lights with multi-tap ballast and use the highest available. Even consider 277V and 120 with different strings of circuits. This might cause transformers for each building, well maybe.

You have to supply lights for any interior stairs, during construction. I'd do this with a CFI cork screws lamps in bird cages.

Centralize the power source and disruption. Your main could be the up to six throws, send correct branch out to each building. Set up another common distribution point inside each building. The opposite of each building might need a 120V power board. You might even consider set up the temp. to each building underground to central point and abandon later.

Frankly, you need an accounting of amps on all the lights to be used. Then consider using 2 to 4 circuits for 120V utilization at each power board(a circuit GFCI protected device can protect two quads of receptacles.) Voltage drop might be a problem to consider for both light stings and branch circuit. Hopefully you will not have to require 120/240 plugs for the floor guy or the welder.

Be sure to spot place lights out of the way or pipe racks(Labs) and duct work everywhere else.

Count it all up and address the service needs. :)

What the power out on the street ?
 

cdslotz

Senior Member
Pretty much what cadpoint said.
Come up with a load calc to determine the main service size with feeders and distribution to the buildings. Distribute panels/tranformers up the core of the multi-floor buildings. I usually do a rough estimate on the distribution and feeders (not getting quotes. Price panels, switches myself), using pvc/alum feeders. We have a stock of TP pedestals, spider boxes, transformers, etc that we cost out at a discount for large jobs.
Once I get the distribution done I usually sq/ft price the building for temp lighting, etc.
Don't forget construction trailers. Will there be a tower crane(s) on the job?

Also, I ALWAYS quote the temporary power as an allowance and I ALWAYS present this number "below the line" and not included in my base bid. That way, temp power has some negotiating wiggle room with the GC. If the GC thinks it's too high, then he can be more specific of what he requires. The same if he thinks it's too low.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
Hello All,
I'm bidding a project that has 3 buildings. A Maintenance Building, Laboratory, and Office Building. I need to figure out what to put in for temp site power. I've never had to figure this out before. Where should I start?

last time i did one of these, it was a 30 acre industrial park build on spec,
and we put two 60 amp stringers with spider boxes per building. there were
ten buildings.

it was tilt up.... we put in 2" pvc from a portable distribution board to
a column in the center of each building, and put a 12x12 nema 3 box
with a couple 60 amp pigtails there for stringers. pulled aluminum wire,
and hypressed on lugs. cut it off flush and buried it after the job.

no power cables between buildings.

you'll need power for job trailers, usually 30 amps 240 is all that is
needed for a job trailer with a window shaker A/C and some minimal
loads.

if there is structural steel, you may need power for a welder bank.

usually 208~230 3 phase, 100 amps will be enough, unless you have
a bank of 8 or 12 welders, then 200 amps.
 
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