Sizing an auxilliary gutter

[george969]

1) I have a 1200A 208V 3p 4w fused disconnect and meter for a restaurant in the electrical room in the basement of a shopping center.
2) I have 4ea 4"PVC conduits leaving the disconnect carrying 4ea 500MCM + 1ea 250MCM traveling approximately 60' to the restaurants electrical closet. For a total of 16ea 500MCM and 4ea 250MCM conductors.
3) These conduits and conductors go thru the floor into the bottom of gutter that is 16"X16"X48". The conduits are entering in a straight line at the back of the gutter on one end. The conductors will be terminated under 5 splice blocks staggered along the 48" gutter.
4) The tenant will install 4ea 400A MB panelboards and will connect those to the gutter with his own conduits all within about 15' of the gutter. The conductors will tap onto the parallel service at the tap blocks.
or
The tenant will set a 1200A MDP on top of the gutter and feed it thru 4 conduits of his and his conductors.

What sized do I need to change the 16"X16"X48" gutter to for it to meet code?

 

[RUWired]

George, if your going to install the disconnect directly over the top of the wireway, you'll need a box rated 8 times the largest conduit entering or leaving the box. If its 4", then a 32" tall box would be required. (314.28(A)1). If you offset the entry and exit conduits, you'll need a wireway 72" long to maintain distance between raceways.(314.28(A)2.

You also need to look at the installation instructions of the power distribution block you are going to use for the minimum recommended size wireway as well. If your using a multi conductor tap lug, then you need to make sure it and the conductors combined doesn't exceed the 75 percent fill of the wireway at any cross section. if it's the ilsco pct-8-600 lug, it won't exceed the limit.
Rick

 

[george969]

So we need a 32" tall by 72" long gutter? What depth? The tenant is actually planning on sitting a MDP on top of the gutter and feeding from the opposite end of the gutter that we installed to terminate the landlords service.

We have a 14" X 14" X 96" long gutter in the elect room supplied by an overhead service into the top of the service gutter. It's 4 sets of copper in 4" pipe terminated with Ilsco blocks. A 1200A disconnect is bottom fed from the gutetr via 4ea 4" nipples to the tenant space. There are also 3ea 200A disconnects on the 14X14X96 gutter. That gutter was approved as OK in size. Was that size also incorrect?

 

[RUWired]

So we need a 32" tall by 72" long gutter? What depth? The tenant is actually planning on sitting a MDP on top of the gutter and feeding from the opposite end of the gutter that we installed to terminate the landlords service.

A sketch would be helpfull, your description sound different from original post.

The 32" tall box was required if the conduits were coming in the bottom and going out the top into the bottom of the MDP. The width and depth is dependant on the requirement from the power blocks. If you also planning to tap additional feeders from the power blocks with the MDP feeders then more info is needed.

Keep in mind, the parallel feeders have to be the same length. Using tap blocks directly under the MDP in a 32" box will be a bear to keep the same length.The Power blocks will have a minimum installation requirement as well. If this was a listed wireway a 16" minimum requirement would be required from the end of the lug to the opposite wall of the block on both sides.(Table 312.6B).

Rick

 

[RUWired]

We have a 14" X 14" X 96" long gutter in the elect room supplied by an overhead service into the top of the service gutter. It's 4 sets of copper in 4" pipe terminated with Ilsco blocks. A 1200A disconnect is bottom fed from the gutetr via 4ea 4" nipples to the tenant space. There are also 3ea 200A disconnects on the 14X14X96 gutter. That gutter was approved as OK in size. Was that size also incorrect?

A wireway with 4 parallel 500 kcmil conductors using splice blocks requires a minimum 16" bending radius per article 376.56(B)3 and table 312.6(B). I say it should have been a 16" wireway. As for the length the 2" conduits would have to meet the 6 x rule from the incoming 4".


Rick