Temporary power

[Halvor]

I need to setup temp power at a Industrial site for a 3 week shut down, I just need power for barge lights that have to be on 24/7 and a receptacle so we have power for temp lighting/tools, no more than 20Amps worth.

The existing transformer that feeds the panel for the barge lights is 45KVA 480v Delta to 208Y/120v, now my question is; If I ran 50A SO cord 500' with a 20A OCPD because of Voltage drop, will the Transformer still function properly and give me the 208Y/120v? or will I be running into issues like the OCPD tripping due to heat over load/ In rush current from trying to draw in 45KVA?

Thank you for all answers and insight you have to offer.

 

[petersonra]

I need to setup temp power at a Industrial site for a 3 week shut down, I just need power for barge lights that have to be on 24/7 and a receptacle so we have power for temp lighting/tools, no more than 20Amps worth.

The existing transformer that feeds the panel for the barge lights is 45KVA 480v Delta to 208Y/120v, now my question is; If I ran 50A SO cord 500' with a 20A OCPD because of Voltage drop, will the Transformer still function properly and give me the 208Y/120v? or will I be running into issues like the OCPD tripping due to heat over load/ In rush current from trying to draw in 45KVA?

Thank you for all answers and insight you have to offer.

Is the cord and 20 A OCPD on the primary or secondary side? If on the secondary side it does not matter.

On the primary side it is possible you could get nuisance tripping.

There is no SO cord listed in table 400.5(A)(1) that has an ampacity of 50 A. The closest I see is 52 A which is #5 conductors. I have never seen #5 conductors, so let's call it #4 which is 60A. A 60 A breaker can be used to protect the primary of the transformer. 45 kVA is about 54 amps at 480 V. I would feel a lot more comfortable with a larger breaker and cord, but 60 A is better than 20 A.

Incidentally, SO cord is only listed for 300 V, IIRC.

 

[zbang]

Disassociated thoughts-

I'm a little confused by the description, is the actual draw only 20amp at 120v? Do you need 3-phase at the barge?
You might be able to use 6/4 SOW (or equivalent) if you only need two hot legs, otherwise you need 5-wire and that's less common (and more expensive).
Buying or renting the cable? A call to the rental house for what they have on the shelf would be useful in designing something, Assume there will be connectors or a j-box involved if using flexible cable.
Is there a panel on the barge and you're running a feeder?
Do any marine regulations apply?

Type S is usually rated for 600v, SJ is only 300v.

 

[hillbilly1]

The 20 will probably not set, once you get it set, you probably won’t have a problem. That being said, using a 50 amp breaker would not be a problem, as you have already limited your load for the temporary power, so voltage drop shouldn’t be an issues.

 

[hillbilly1]

Disassociated thoughts-

I'm a little confused by the description, is the actual draw only 20amp at 120v? Do you need 3-phase at the barge?
You might be able to use 6/4 SOW (or equivalent) if you only need two hot legs, otherwise you need 5-wire and that's less common (and more expensive).
Buying or renting the cable? A call to the rental house for what they have on the shelf would be useful in designing something, Assume there will be connectors or a j-box involved if using flexible cable.
Is there a panel on the barge and you're running a feeder?
Do any marine regulations apply?

Type S is usually rated for 600v, SJ is only 300v.

I take it, the op is feeding a 45 kva transformer at the barge? So it will be 480 three phase, and he will only need a four wire cord.