southman
Member
- Location
- jacksonville, fl
I have 16 temp office trailers coming in. They each have two (2) 125 amp panels with 120/240 single phase service. What size 3-phase transformer should I spec out?
Transformer Sizing
- Thread starter southman
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You need to know the approximate load on each panel.
Do you mean 120/208V single phase service to each trailer instead of 120/240V?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Good question, that would be my guess.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Load calc! We don’t need no stinkin’ load calc!
Just total it all up. It only comes out to ~1.5 MW. :blink:
No problem.
Demand factors and all that stuff is too much trouble.
Just total it all up. It only comes out to ~1.5 MW. :blink:
No problem.
Demand factors and all that stuff is too much trouble.
southman
Member
- Location
- jacksonville, fl
The trailer spec provided has "120/240 single phase", but you're right it has to be 120/208. The HVAC is 6.0 ton unit with 20kw heat strip.
JFletcher
Senior Member
- Location
- Williamsburg, VA
Welcome to the forum!
is that HVAC per unit or one serving all trailers, and is that 20kW rating at 240V or 208V? single phase?
is that HVAC per unit or one serving all trailers, and is that 20kW rating at 240V or 208V? single phase?
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Unless you want to spec an insanely large service like I joked about earlier, you need a load calc for each trailer before you can even think about what service size is need.
HVAC, receptacles, lights, various equipment, kitchens if applicable, and such.
Load calc! We don’t need no stinkin’ load calc!
Just total it all up. It only comes out to ~1.5 MW. :blink:
No problem.
Demand factors and all that stuff is too much trouble.
Yep. That could suffice.
Maybe, a 1,000 kVA could perhaps do it also (full-load amps = 2,775A, maximum amps per phase for 16 trailers @250A is 2,600A).
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Randomly guessing, barely paying attention, and cheating like all get out I get something somewhere like maybe a 300 kVA tranny and 800A main gear.
Haphazard calculation at best when flying blind.
Haphazard calculation at best when flying blind.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
But 300 kVA is a standard size.
I am gonna need you to be a little more “creative”.
run it hot and hope for the best
junkhound
Senior Member
- Location
- Renton, WA
- Occupation
- EE, power electronics specialty
Typically the POCO will size the number and size of the trannies.
Depending on how spread out the trailers are, I'm guessing they will just put in 3 separate 120/240 1 phase, 25 kVA and call it good unless you fry one of them soon.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
run it hot and hope for the best
Or maybe do what I kinda did and figure 2 trailers wind up as basically storage units and very little loads. No HVAC or other stuff, just a few lights.:angel:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
OP has not said whose tranny he is specing for.
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