Do xfmrs need flexible pipe connections, where stated in NEC

[Curt Zierke]

I was always under the assumption that you could not pipe rigid into a dry type xfmr due to vibration. A co-worker asked where it was stated in the code book, and I could not find it.
Example: 2" EMT from a 480v Main Panel to a step down dry type xfmr hung from a red- iron structure, feeding a 208v sub panel below. Assume all wire sizes and equipment grounds and bonding is correct.

Question: Can I pipe directly into and out of the xfmr with the EMT.

 

[tshea]

Yes.

 

[petersonra]

Re: Do xfmrs need flexible pipe connections, where stated in

Re: Do xfmrs need flexible pipe connections, where stated in

I was always under the assumption that you could not pipe rigid into a dry type xfmr due to vibration. A co-worker asked where it was stated in the code book, and I could not find it.
Example: 2" EMT from a 480v Main Panel to a step down dry type xfmr hung from a red- iron structure, feeding a 208v sub panel below. Assume all wire sizes and equipment grounds and bonding is correct.

Question: Can I pipe directly into and out of the xfmr with the EMT.

the code allows the use of flexible connections where necessary due to vibration issues but does not require it.

 

[tom baker]

It mostly done with flex to make the job easier. Perhaps to reduce noise from hummmm

 

[georgeswe]

I have done this many ways from Pipe , LBs , gutter , flex , sealtight If you read the install directions on your XFMR the metal frame that you are connecting to is stationary and the "guts" that are on vibration dampers. With most of the instructions i have seen the bots holding the Guts to the frame need to be loosened after delivery, if you dont do this you will have excessive vibration.



The flex looks like my 3 yr old did it , and probably looks that way.