Step down xfmr feeder

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thumper_tx

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A consultant where I work wants to install an A/C unit (480 v 70 amp load) in a 480/277 panel that is primarily used for lighting and is moderately loaded.
The problem is that the panel is on the 2nd floor and the proposed a/c unit is on the first floor. This is not a good idea in several ways, but they want a specific reference in the code that prohibits this.
Is it acceptable if labeled properly?

Thanks,


Ron in Texas
 
It is acceptable - period (if load calc OK), but not a great idea for a lighting panel, especially for a load that size.
 
Sorry for the delay.

The xfmr is for a cooling unit in a lab. I do not like putting the load on a lighting panel. It is a 60 amp breaker with a true running load of 40 amps or so.
The lighting panel is lightly loaded.

Thanks.
 
You did not mention the occupancy situation but you might want to make sure to take 240.24(B) into consideration.
 
thumper_tx said:
A consultant where I work wants to install an A/C unit (480 v 70 amp load) in a 480/277 panel that is primarily used for lighting and is moderately loaded.
The problem is that the panel is on the 2nd floor and the proposed a/c unit is on the first floor. This is not a good idea in several ways, but they want a specific reference in the code that prohibits this.
Is it acceptable if labeled properly?

Thanks,


Ron in Texas
Click to expand...

There is no code violation and I see no reason that is is a bad design assuming the load calculations are OK.
 
Thank you all for the input.
It has been determined that the installation is OK as long as the location for the disconnecting is clearly marked.

Ron
 
thumper_tx said:
Thank you all for the input.
It has been determined that the installation is OK as long as the location for the disconnecting is clearly marked.

Ron
Click to expand...
Take a look at 440.14.

No one said you could use the CB on another floor as the sole means of disconnection.

No problem with feeding it from there.
 
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