Design input - Revised

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horsegoer said:
Ok a little potential change.

Say I wanted to eliminate the 225A panel( with the 125A, and (2) 60A branch breakers) and use (3) disconnect switches instead could I doo that.
I'd think so but then how would I feed (3) disconnects from a transformer. Run one feed from transformer to a trough, splice, then feed the discos?

Would the disconnects have to be fused? Also 2P3W disconnects?
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The disconnects would need to be fused.
You could run a separate feed from the transformer to each disconnect as long as each met the 240.21(C) transformer secondary rules.
 
horsegoer said:
Ok a little potential change.

Say I wanted to eliminate the 225A panel( with the 125A, and (2) 60A branch breakers) and use (3) disconnect switches instead could I doo that.
I'd think so but then how would I feed (3) disconnects from a transformer. Run one feed from transformer to a trough, splice, then feed the discos?

Would the disconnects have to be fused? Also 2P3W disconnects?
Click to expand...
If I remember correctly the secondary conductors must terminate on an OCPD so the wireway is not an option.
 
I gave my breakdown/one line to someone in my office and he responded with below?

P=E x I x 1.73

45000= 208v x I x 1.73

45000/360=I=125 amp 3 ph for trailers with AC & Heat?

I don't follow his logic/calc exactly. I questioned what he meant by 3P for trailers.
 
horsegoer said:
I gave my breakdown/one line to someone in my office and he responded with below?

P=E x I x 1.73

45000= 208v x I x 1.73

45000/360=I=125 amp 3 ph for trailers with AC & Heat?

I don't follow his logic/calc exactly. I questioned what he meant by 3P for trailers.
Click to expand...
That is the output of a 3Ø, 45 kva transformer.
 
Ok so with the new scheme of feeding 2P disconnects switches from a 3 phase xfrmr instead of feeding a 3P 4W panel, what would the make up of the cable/wires be from the secondary to the disconnects? 2 phase conductors or 3 phase conductors. Its weird because the xfrm is 3P but the disconnects are 2 pole.
 
horsegoer said:
Ok so with the new scheme of feeding 2P disconnects switches from a 3 phase xfrmr instead of feeding a 3P 4W panel, what would the make up of the cable/wires be from the secondary to the disconnects? 2 phase conductors or 3 phase conductors. Its weird because the xfrm is 3P but the disconnects are 2 pole.
Click to expand...
The disconnects in those sizes are probably 3 pole but you'll only need to use two poles.
 
#1 disconnect to X1-X2 & Neutral XO
#2 disconnect to X2-X3 & XO
#3 disconnect to X1-X3 & X0
all + SSBJ
 
horsegoer said:
Geniuses ...lol. Thank you. It was just a weird concept to me to have a 3P xfrm but coming off it with only 2 phase conductors.
Click to expand...

Right, but keep in mind that you are using all three phases.

You have 3 separate loads, and each of these loads only uses 2 phase conductors.

But you distribute these 3 loads to use all 3 phases.

Jon
 
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