XFMR Disconnect

[4fun]

I am hoping someone can help with this question. I have a customer who wants to install a primary disconnect onto an existing pad mounting 480 - 208/120 volt XFMR. They would like to mount it onto the side of the XFMR itself and simply use nipples in and out of the primary compartment. The XFMR is fed with a 3 phase 70 amp breaker located in a remote panelboard. I cannot find where this would be prohibited in the NEC. The alternative would be to breakup the concrete and relocate the conduit.

Any thoughts would be appreciated.
Rich

 

[don_resqcapt19]

I don't see an issue as long as something other than the conduit nipples is used to support the disconnect.

 

[ron]

Is the proposition to actually bolt the disconnect directly to the transformer or to channel that is mounted to the floor?

 

[Smart $]

While not prohibited by Code, you may run into issues if the intent for the disconnect is to perform servicing where access to the compartment is required. Under a bona fide safety program, the compartment will still have energized conductors when the disconnect is opened, unless the remote breaker is also off... then the opened breaker will have to comply with LOTO. Not impossible, but it leaves me wondering what the intent for the disconnect is.

 

[iwire]

Energized conductors are not an issue are they?

No exposed live parts and we are good to go right?

Just like factory installed disconnects in roof top units and countless other machinery.

 

[don_resqcapt19]

Is the proposition to actually bolt the disconnect directly to the transformer or to channel that is mounted to the floor?

I would not have a problem with it bolted to the transformer enclosure as long at the location does not interfere with the access to the connections.

 

[Smart $]

Energized conductors are not an issue are they?

No exposed live parts and we are good to go right?

Just like factory installed disconnects in roof top units and countless other machinery.

Possibly, now that you bring it up. What is OSHA's position?

The places I work nowadays require everything above 50V be de-energized related to the piece of equipment to be worked on (when practicable)... otherwise hot PPE. Insulated and touch-safe do not qualify.

 

[4fun]

Thanks for the replies. I couldn't find a reason why it would not meet code but I guess I just needed a little reassurance. It will be mounted properly and is just for an easy method of shutting down the equipment.

Sent from my DROID RAZR using Tapatalk

 

[rhovee]

I would only mount the disconnect in the "buffer" zone. You could get nailed for not following the manufactures installation instructions on the transformer if you go above the line which is usually above the coils.