A fellow electrician called me to ask about an installation he did. I will do my best to describe it...
From a POCO transformer he ran 1 - 3" raceway to a 200amp underground meter cabinet (single phase). From the meter cabinet he ran another 3" raceway to the building. This installation is at a cell site which requires the meter to be mounted seperate from the building.
The prints called out the POCO transformer was 240v when in actuality it is 480V. This mistake required the addition of a 480-240/120v transformer at the building. The inspector requested a means of disconnect be installed prior to the second transformer. The electrician nippled out the back of the meter cabinet into a disconnect. He then installed the 3/0 wire in the following manner:
1) The 3 - 3/0 coming from the POCO transformer enter the bottom of the meter cabinet, travel thru a nipple from the meter cabinet into the disconnect and terminate on the line side of the disconnect.
2) 3 - 3/0 come off the load side of the disconnect, travel thru another nipple back into the meter cabinet and terminate on the line side of the meter.
3) 3 - 3/0 come off the load side of the meter and enter the 3" raceway located in the bottom of the meter cabinet and travel to the transformer.
The POCO will not accept the installation due to the fact that the wires from their transformer terminate on the disconnect, not the meter.
The inspector does not like the installation but says there is nothing in the Code against it.
Before I got to the end I was thinking that Com Ed would not like that. Not much you can do to avoid changing it if the utility does not like it.
What type of meter and cabinet are you talking about? A pedistal or CT cabinet. For 200 amp you could just get a self contained meter with 200 amp OCP. I don't know if you have a CT meter but I don't believe it's needed.
I was thinking he could just change it so it went thru the meter 1st then the disco. I thought that would be a violation because it would be a feeder going back thru the meter again. Can't find anything about it.
You have a single phase 3 wire 480v?
Just be happy it's not your problem.
Re: Need opinions on this installation#60898 01/13/0607:40 AM01/13/0607:40 AM
the first question is this 480 off of a three phase service nearby ? or is this just a single phase 240/480 secondary transformer?if the later is true why couldn't they just change the transformer to a 120/240 unit? usualy the power company will supply what ya need.also a 480 volt form 2s meters are made,i have one of these weird things,the guy that i got it from said it was for interstate lighting.
Re: Need opinions on this installation#60901 01/13/0609:45 PM01/13/0609:45 PM
The reason for the disconnect being added is due to the second transformer being needed after it was discovered that the POCO transformer was 480v, not 240v as called out in the drawings.
I agree the best remedy is to relocate the 3" raceway that feeds the 480v-240/120v tranformer from the meter pedestal to the disconnect. I am guessing this would require substantial work.
I believe the POCO transformer is 3phase 480volt.
Now, if the disconnect was equipped with locking tabs that the POCO could install their own lock on, would that satisfy the worry of having someone tamper with the feed before it hits the meter ?
The G.C. probably told the E.C. to correct the problem the cheapest way possible because he (G.C.) doesn't want to go back to the cell company with a change order for the additional work. The E.C. should have insisted the 3" raceway be relocated to the disconnect.