Sleeves

[Alwayslearningelec]

Have many 4" pvc duct bank conduits that transition to RGS elbows through slab into bottom of gear. New slab on grade. Any reason you'd need to put sleeves in before the pour or could you just install your elbows/conduit that rise up through the slab before they pour? Thanks

 

[Eddie702]

No sleeves needed with RGS unless the engineer specs it.

 

[infinity]

Is the conduit being installed before the pour? Remember you're only allowed 3" of conduit above the slab or concrete pad.

 

[Alwayslearningelec]

Is the conduit being installed before the pour? Remember you're only allowed 3" of conduit above the slab or concrete pad.

Really? That's seems odd? So when turning up into bottom of gear as I described it's only 3" of conduit past the slab into the gear? You've done that before? What code section?

 

[infinity]

Really? That's seems odd? So when turning up into bottom of gear as I described it's only 3" of conduit past the slab into the gear? You've done that before? What code section?

408.5. I even wrote a proposal to have it changed to 6" but it was rejected. 3" is stupid as was the response from the CMP.

 

[Alwayslearningelec]

Wow. So That's how it's done, 3" is left?

 

[infinity]

Wow. So That's how it's done, 3" is left?

You cannot have more than 3" even if you have 3' of space. Don't worry no one ever checks.

 

[augie47]

It's enforced here. I've had to install a bottom auxiliary gutter to satisfy the AHJ.(That works but you have to keep 404.8, the 6'7" rule in mind)

 

[infinity]

It's enforced here. I've had to install a bottom auxiliary gutter to satisfy the AHJ.(That works but you have to keep 404.8, the 6'7" rule in mind)

Stupid rule because the 3" is completely arbitrary. If a large space exists above the raceways why limit the length to 3"?

 

[ModbusMan]

Probably to keep people from tripping completely, rather than just stumbling. At any rate, during construction I've seen them sticking two or even three feet out. Then after the pour, someone comes in with a sawz-all and lops them to spec.

 

[don_resqcapt19]

Probably to keep people from tripping completely, rather than just stumbling. At any rate, during construction I've seen them sticking two or even three feet out. Then after the pour, someone comes in with a sawz-all and lops them to spec.

This is only for the conduits that stub up into the bottom of open bottom equipment

While in most cases, Rob, is correct that 3" is overly restrictive, but I have installed switchgear where the bottom connections were around 9" above the floor. With those, if you have more than 3" in the bottom of the gear, you can run into problems with the bending space that is required by 312.6(B).

 

[infinity]

This is only for the conduits that stub up into the bottom of open bottom equipment

While in most cases, Rob, is correct that 3" is overly restrictive, but I have installed switchgear where the bottom connections were around 9" above the floor. With those, if you have more than 3" in the bottom of the gear, you can run into problems with the bending space that is required by 312.6(B).

That was my point in the proposal there are already minimum required spacing distances so why 3"? As long as the other requirements like the aforementioned bending space are met the 3" can be irrelevant.

 

[don_resqcapt19]

That was my point in the proposal there are already minimum required spacing distances so why 3"? As long as the other requirements like the aforementioned bending space are met the 3" can be irrelevant.

If the product standard permits the termination points to be 9" above the bottom, the 3" rule is required. Not sure what that product standard says.

 

[Fred B]

Don't see anything of 408.5 indicating a 3" requirement related to the concrete pour level, it is only in relation to entry of the bus enclosure, and as mentioned by Don. It also serves to limit the length of the "unsupported" conduit. There is also in that section a minimum spacing for the bus from the bottom of the enclosure Table 408.5
408.5 ..... The conduit or raceways, including their end fittings, shall not rise more than 75 mm (3 in.) above the bottom of the enclosure.

Now if there is going to be a pad mount xfer or a floor mount enclosure the final height of the conduit would obviously be limited to allow for wire bending space, that is what 408 is about. Seen many that are much longer in pre-pour state to both allow for pour to happen without getting concrete into the conduit and allow for visibility and reduce tripping hazard. They do have sleeves that are capped to allow the conduit to be installed post-pour but that is obviously for multi-level where there will be access from below.
Even if the Conduit is installed higher I would cap off the conduit to prevent foreign material entering during construction. Have yet to see a concrete guy that doesn't get the pumped grout all over the place.