Conduit connections to equipment

[rlqdot]

I normally see the final conduit connection to "moving" equipment (like motors or transformers) made with some form of flexible wiring methods. is there a code section that REQUIRES flex or are those final flex sections of conduit the result of project specifications? I have a client that wants to extend EMT to vehicle hoists and other automobile service equipment and i am recommending against it, proposing to use flexible cord drops or other flexible methods. power will drop from roof above - sometimes as much as 15 feet from J-box above to top of equipment. can i use the vehicle lift posts as a point to secure EMT? if i have more than 10 feet from roof J-box to top of lift post, do i need to install strut to support the EMT?

 

[infinity]

Except for passing an expansion joint the NEC is pretty much silent on when a flexible raceway is required.

 

[augie47]

Any conduit method must be supported be the NEC. There are provisions for installing GRS conduit unsupported (344.30).
Cord drops to lifts are not uncommon, often with a twist lock at the equipment.

 

[don_resqcapt19]

While some type of flexible connection is common, there is little in the way of equipment that actually moves or vibrates enough to require a flexible connection. I think typically the flexible connection is used because the cost of the materials and the labor to install, is less than the labor and material required to hard pipe. In addition, the conduit is often run and wire pulled prior to the equipment being set in place.

Yes, I know that the code, in 300.18(A), requires a complete raceway system before pulling wire, but it has always been a common practice to pull the wire prior to the final equipment connection around here.

 

[rlqdot]

thank you to all of you for your input. i am suspecting that the final piece of flex may be a result of project spec requirements and / or what Don stated with respect to the equipment not being set at the time wire is pulled. and, i guess you could argue that the raceway is complete with the exception of the final connection to the equipment that is not yet in place.

thanks again. learn something new every day! somehow i had convinced myself that NEC required the flex connection.

 

[tom baker]

And we often use flex as it makes the connection easier, eg to a motor that doesn’t move

 

[Little Bill]

Any conduit method must be supported be the NEC. There are provisions for installing GRS conduit unsupported (344.30).
Cord drops to lifts are not uncommon, often with a twist lock at the equipment.

Do you mean stacking up a bunch of NEC books for the conduit to rest on, or an actual member of the CMP for the NEC has to physically come in to hold up the conduit?

 

[Chamuit]

Except for passing an expansion joint the NEC is pretty much silent on when a flexible raceway is required.

I would look to the manufacturer's instructions, too.