TRANSFORMER INSTALL 112.5 KVA 480 to 208Y/120

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I am willing to bet if you pull the lugs off the terminals you will find they are marked.


However, if this is a 480-208Y/120 transformer XO will be the larger terminal that is electrically connected to all three coils. (I would say the second large terminal from the left.)

The three remaining larger terminals will be the remaining Xs

As far as which one is 1 2 or 3, that is pretty much up to you.
 
If I was tasked with wiring this one up I would change the lugs, the ones on it are two long and just make it hard to get the wires formed neatly. Also the clearance between XO and X2 is closer than I would be comfortable with.

Lastly because of the bonding jumper and GEC that needs to go to XO I would need at least a 3 conductor lug.
 
iwire said:
If I was tasked with wiring this one up I would change the lugs, the ones on it are two long and just make it hard to get the wires formed neatly. Also the clearance between XO and X2 is closer than I would be comfortable with.
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I agree.

Lastly because of the bonding jumper and GEC that needs to go to XO I would need at least a 3 conductor lug.
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Do you bond the XO in the transformer most of the time or all of the time?

In my area it is typically bonded at the disconnect. I am curious if we are out of the mainstream with this practice.
 
I prefer to do it in the transformer, IMO it keeps the panel neater but of course it is just a personal preference and one is no better or worse than the other.
 
I agree that one is a good as the next.

For a long time we had only one inspector and he preferred it in the panel, so that was the way everybody did it/learned to do it. I talk to guys all the time that have moved here from other places and they claim to have never seen it done that way.
 
iwire said:
If I was tasked with wiring this one up I would change the lugs, the ones on it are two long and just make it hard to get the wires formed neatly. Also the clearance between XO and X2 is closer than I would be comfortable with.

Lastly because of the bonding jumper and GEC that needs to go to XO I would need at least a 3 conductor lug.
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I agree with the long lugs but if you look at the bottom right you will see that the X0 is already bonded with a strap going to the X0 buss that runs behind the other lugs, and find the terminal connected to this buss and you have your X0 which again I agree with Bob it the second double barrel lug from the left the small single lugs are H1-3 primary.

Also along with shorter lugs I would change to over and under lugs where one barrel is stacked over the other barrel as they are much narrower and you don't risk the X0 and X2 coming together as easy as it is now if the bolt was to come loose.

My guess (been awhile since I been in one of these) is:

From left to right:
X1, H1, X0, X2, H2, H3, X3
Taps I believe are + 2%x4 -2%x2 where at now is center 100% 4 above the center tap is plus + and two below center is minus -
 
Hey Hurk, I agree with your assesment of the lugs, with one exception. Since the windings sit on rubber pads to help keep the transformer quiet, the bonding strap on the right is there to connect the metal that supports the coils to the transformer can.

The XO would still remain isolated until a bond is made to the can, like Iwire would, or at the panel like I would.
 
ActionDave said:
Hey Hurk, I agree with your assesment of the lugs, with one exception. Since the windings sit on rubber pads to help keep the transformer quiet, the bonding strap on the right is there to connect the metal that supports the coils to the transformer can.

The XO would still remain isolated until a bond is made to the can, like Iwire would, or at the panel like I would.
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Absolutely, the strap is just bonding the coils frame and not XO.
 
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