Estimating XFMRS

[horsegoer]

When I put in a xfmr, I guess I need to put in a flex connection. I have never done this and others I work with might tell me it's in the install unit. I always put in whips for motors. Does a xfrmr require a flex connections by code? It is a vibrating piece of equipment.

Thanks.

[iwire]

No a transformer is not required to have a flexible connection.

It is good practice if noise is a factor.

BTW, where does the NEC require a flexible raceway for vibrating equipment? ;)

[ceb58]

No flex is not requried but the person who has to change it out one day will thank you for doing it. Or cuss you for not doing it:smile:

[Rockyd]

Hey Bob, don't have my code book handy (got left at work) but, have always hooked up transformers with flex, just as a faster, professional install.

Could a case be built around wire planning in the future(90.5 if I recall)?

[cadpoint]

Hey Bob, don't have my code book handy (got left at work) but, have always hooked up transformers with flex, just as a faster, professional install.

Could a case be built around wire planning in the future(90.5 if I recall)?

90.8 wiring planning
(A) Future Expansion and Convienience

Is what you might be thinking...

[iwire]

Hey Bob, don't have my code book handy (got left at work) but, have always hooked up transformers with flex, just as a faster, professional install.

Could a case be built around wire planning in the future(90.5 if I recall)?

90.8 is a suggestion not a requirement, I see no 'shall' in 90.8. :)

I have wired transformers with most all methods, flex, EMT, Wireway, PVC.

[cadpoint]

90.8 is a suggestion not a requirement, I see no 'shall' in 90.8. :)

I have wired transformers with most all methods, flex, EMT, Wireway, PVC.
Lets go with, it's the introduction. The Code 2008 doesn't say that its not part of Code, if it does please feel free to state otherwise.

[tyha]

I always thought it was done because of the exception to the securing flex within 12" of the box or enclosure. It can be moved to 3' in situations with vibrating equipment.

[tyha]

also, inside of our x-fmr assembly is 10' of whatever size flex. we always do it. oftentimes it is in the project specifications. as a matter of fact we had to adjust ours one time about a year ago because we were bidding a high school comming out of the ground and the specs for the x-fmr terminations called for liquid tight and not just flex. have absolutely no idea why but they did.

[chris kennedy]

No flex is not requried but the person who has to change it out one day will thank you for doing it. Or cuss you for not doing it:smile:
Motors sure, how many transformers have you seen go south?

Is there a huge time difference removing conduit connectors and couplings with large wire compared to FMC?

[horsegoer]

Tyha, yes that is where I saw it the other day......the spec. It called for flex for all vibrating connections and listed xfrmrs as one.

[electricalperson]

most transformers i install i use flex for. ive also used non flexible wiring methods for them too. it makes it a little easier just to flex it in

[iwire]

WOW. :grin:

The NEC does not require flex to a transformer or a motor.

Specifications may and sometimes common sense mandates flex.

[jmsbrush]

Do you need a labor unit, What size transformer?

[ceb58]

Motors sure, how many transformers have you seen go south?

Is there a huge time difference removing conduit connectors and couplings with large wire compared to FMC?

Saw one this weekend. 30 kw I installed about 1 1/2 years ago mounted about 12 foot off the floor. Remove the flex, four bolts and set it off the rack with forklift, set new one bolt down, reconnect in about 2 hrs. Do not know what happened to old transformer lost one leg on the secondary. Will know later on this week from the factory tec. department