# 208 to 480V 3 phase Step-Up



## RandyJ

I have a power supply used for charching batteries in our facility. The input to the power supply is 480V 3 phase (no neutral, just 3 phases and 1 ground). I want to use this in our facility but we only have 208 3 phase. Short of having a major change to our facility power, I thought of this. I want to get a small step-up transformer (about 9KVA) and wire it to plug in to one of our 208 3 phase 30 Amp receptacles. The output of the transformer would have a 480V 3 phase receptacle (no neutral, just 3 phases and a ground). So here is the question: Is this possible and would it violate any electric code?


----------



## Pete m.

I would suggest looking at article 450 in conjunction with 240.21.

At first glance it seems you are missing secondary overcurrent protection if you plan to terminate the secondary conductors directly to a receptacle.

Also keep in mind that 250.30 will also be applicable.

Pete


----------



## erics37

You can:

- Run it corner-grounded
- Get a delta-wye transformer and derive a neutral, bond it etc. and simply not utilize it (probably easiest)
- Run ungrounded (there's a list of qualifications you have to meet if you do it this way, not likely you'll meet them)

As mentioned, you'll probably need to consider secondary protection and/or disconnecting means.


----------



## wildleg

since you aren't an electrician, you will need to have one do this for you.

as the others said, it would probably be best to have one wired to a branch ckt, with primary protection, but yes it should be a simple install.


----------



## Introyble

Im lost again :laughing: I love playing Cletis.

So, the OP states he has 3 phase 208. Ok, where did that come from?

Are we to assume he got three phases from a single phase primary?


----------



## BBQ

If this battery charger is like most 480 volt battery chargers I have worked with it can be reconfigured for use at 208 as well. I would look into that before buying any transformer. 

Also keep in mind if the unit required 20 amps at 480 it will need close to 50 amps at 208. 

Get an electrcian involved, as the others have pointed out your plan is not going to meet code and I doubt it would work anyway.


----------



## bobelectric

I agree. Read the installation book and it maybe changed to 208 3ø And you save the the facility money and look like a star.​


----------

