Conduit termination required?

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wrobotronic

wrobotronic

Senior Member
Location
Colorado
Hello All,
i have a situation where a contractor is telling me to free air conductors that are feeding a huge generator. The main run is PVC from the ATS and pops up inside the generator enclosure. Then flex from there to the OCPD cabinet.

basically, the UG 3 1/2” pvc needs to transition to 3 1/2” flex to get in the bottom of cabinet.
He wants me to cut off the PVC at the ground and eliminate the flex, thus free air about 2 to 3 feet.

I was was under the impression that the raceway needs to be completed from start to finish.
While he says it’s allowed because the inside of the generator is only accessible by authorized personnel.

is there a code section requiring the conduit run to terminate/ be completed. Or is he right (if so is there an article that covers his method)?
 
wrobotronic said:
Hello All,
i have a situation where a contractor is telling me to free air conductors that are feeding a huge generator. The main run is PVC from the ATS and pops up inside the generator enclosure. Then flex from there to the OCPD cabinet.

basically, the UG 3 1/2” pvc needs to transition to 3 1/2” flex to get in the bottom of cabinet.
He wants me to cut off the PVC at the ground and eliminate the flex, thus free air about 2 to 3 feet.

I was was under the impression that the raceway needs to be completed from start to finish.
While he says it’s allowed because the inside of the generator is only accessible by authorized personnel.

is there a code section requiring the conduit run to terminate/ be completed. Or is he right (if so is there an article that covers his method)?
Click to expand...


I don't understand how you have conductors "Feeding" a generator. The Main run should be "From" the generator "To" the transfer switch.

Regardless,

If the Overcurrent protection device of the Generator is located inside the generator housing, as long as proper bonding is in place, I don't see how this would be any different then conduits turning up into the open bottoms of Pad Mount Transformers and Distribution Panelboards seen on a daily basis.

JAP>
 
jap said:
I don't understand how you have conductors "Feeding" a generator. The Main run should be "From" the generator "To" the transfer switch.

Regardless,

If the Overcurrent protection device of the Generator is located inside the generator housing, as long as proper bonding is in place, I don't see how this would be any different then conduits turning up into the open bottoms of Pad Mount Transformers and Distribution Panelboards seen on a daily basis.

JAP>
Click to expand...

Touché. My words were not used properly. My apologies. The conductors “from” the Generator “to” the ATS are the ones in question.
 
I'm still trying to figure out why someone would suggest to cut it off at the ground instead of flexing from it to the OCPD Enclosure inside the Gen Set.

Something's telling me there's more to this story.


JAP>
 
There would be no reason for him to want to eliminate the Flex if it was already installed, or, you had planned on installing 2 or 3 feet for a neater installation.

I don't get it.


JAP>
 
look at it this way- as long as the stubs were properly layed out- it is nice having a raceway from the ats to the gen cabinet... then you dont have to fly the gen out to re-pull or whatever...with that being said, i sure see alot of facility generators with flying splices. pull them, through on some liquid tight then drop the gen on it.

ok, flying conductors, not splices... oops.
 
jap said:
I'm still trying to figure out why someone would suggest to cut it off at the ground instead of flexing from it to the OCPD Enclosure inside the Gen Set.

Something's telling me there's more to this story.


JAP>
Click to expand...
Suggesting cutting at the ground was clearly a poor choice. That's why I come here, to make sure I get it right and get different angles. Have things pointed out to me and bring me down a peg when I get my head in the clouds...

The problem we are having with flexing from the PVC to the OCPD enclosure is the flex would go to several different spots on said enclosure. We have 4x 3 1/2" raceways... so I guess the question is one of aesthetics. The bossman thinks free air(ing) the conductors will make for a better looking installation.

Sent from my SM-G965U using Tapatalk
 
wrobotronic said:
Hello All,
i have a situation where a contractor is telling me to free air conductors that are feeding a huge generator. The main run is PVC from the ATS and pops up inside the generator enclosure. Then flex from there to the OCPD cabinet.

basically, the UG 3 1/2” pvc needs to transition to 3 1/2” flex to get in the bottom of cabinet.
He wants me to cut off the PVC at the ground and eliminate the flex, thus free air about 2 to 3 feet.
...
Click to expand...

I think we still don't have enough information. You have a 'cabinet' inside an 'enclosure'? Normally the NEC allows conductors to be run individually inside 'enclosures', and that's not the same as 'in free air'. What is it about this enclosure that makes you feel differently? Just it's size, or anything else? Maybe a pic of this 'enclosure' would help.
 
jaggedben said:
I think we still don't have enough information. You have a 'cabinet' inside an 'enclosure'? Normally the NEC allows conductors to be run individually inside 'enclosures', and that's not the same as 'in free air'. What is it about this enclosure that makes you feel differently? Just it's size, or anything else? Maybe a pic of this 'enclosure' would help.
Click to expand...
I cant for the life of me get a picture uploaded... I'm quite frustrated with it.. not sure wtf I'm doing wrong... sorry

Sent from my SM-G965U using Tapatalk
 
wrobotronic said:
I cant for the life of me get a picture uploaded... I'm quite frustrated with it.. not sure wtf I'm doing wrong... sorry
Click to expand...
No apologies necessary. :) Image on your computer?

Click on 'insert image' icon above the response window (second row, square frame icon next to the icon with the red X), click on 'from computer', click on 'choose file', navigate to your image, click on it then on 'open', then click on 'upload file(s).
 
wrobotronic said:
Hello All,
i have a situation where a contractor is telling me to free air conductors that are feeding a huge generator. The main run is PVC from the ATS and pops up inside the generator enclosure. Then flex from there to the OCPD cabinet.

basically, the UG 3 1/2” pvc needs to transition to 3 1/2” flex to get in the bottom of cabinet.
He wants me to cut off the PVC at the ground and eliminate the flex, thus free air about 2 to 3 feet.

I was was under the impression that the raceway needs to be completed from start to finish.
While he says it’s allowed because the inside of the generator is only accessible by authorized personnel.

is there a code section requiring the conduit run to terminate/ be completed. Or is he right (if so is there an article that covers his method)?
Click to expand...

I've seen this a number of times. It is my opinion that it is not code compliant as the genset weather housing is not an electrical enclosure, rather a generator set enclosure. I've heard the argument that this is no different than open bottom switchgear but I don't agree.
I've most often seen it done where not enough thought and study of the genset and enclosure was put into the roughing stage of the conduits in the slab and they end up with a situation where there is no way to gracefully flex to the breaker enclosure. Sometimes the stub up is even beneath an obstruction and you can't even get a fitting on it , let alone a piece of flex.
 
texie said:
I've seen this a number of times. It is my opinion that it is not code compliant as the genset weather housing is not an electrical enclosure, rather a generator set enclosure. I've heard the argument that this is no different than open bottom switchgear but I don't agree.
I've most often seen it done where not enough thought and study of the genset and enclosure was put into the roughing stage of the conduits in the slab and they end up with a situation where there is no way to gracefully flex to the breaker enclosure. Sometimes the stub up is even beneath an obstruction and you can't even get a fitting on it , let alone a piece of flex.
Click to expand...
Thank you for that. I think at this point I am going to let the AHJ make the call... I will use the 300.12ex2 as my case, and hope he agrees.

I don't wanna get to far in the weeds and argue semantics, but the exception just says "open bottom equipment", and doesn't mention the need for it to be an "electrical enclosure".

That said, my gut agrees with you. I will install and NOT cut the PVC at the pad, but keep it above to allow for flex attachment should the AHJ make that call...

I am very grateful for the help I receive here..

Sent from my SM-G965U using Tapatalk
 
texie said:
I've seen this a number of times. It is my opinion that it is not code compliant as the genset weather housing is not an electrical enclosure, rather a generator set enclosure. I've heard the argument that this is no different than open bottom switchgear but I don't agree.
I've most often seen it done where not enough thought and study of the genset and enclosure was put into the roughing stage of the conduits in the slab and they end up with a situation where there is no way to gracefully flex to the breaker enclosure. Sometimes the stub up is even beneath an obstruction and you can't even get a fitting on it , let alone a piece of flex.
Click to expand...

+1
 
wrobotronic said:
Thank you for that. I think at this point I am going to let the AHJ make the call... I will use the 300.12ex2 as my case, and hope he agrees.

I don't wanna get to far in the weeds and argue semantics, but the exception just says "open bottom equipment", and doesn't mention the need for it to be an "electrical enclosure".

That said, my gut agrees with you. I will install and NOT cut the PVC at the pad, but keep it above to allow for flex attachment should the AHJ make that call...

I am very grateful for the help I receive here..

Sent from my SM-G965U using Tapatalk
Click to expand...

All this time I thought you were describing an existing installation.

Seems as though you are still in the rough in stage.

Regardless of whether or not the conductors are allowed to be free aired or need to be flexed inside of the generator, as others have suggested, the most common thing to do is to keep the stub ups high enough above the slab to do something with.

At least leave enough to glue a TA and Bushing onto the stubup, if it comes to that.

JAP>
 
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