Floating Docks

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Simpsonelectric

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Greetings all, I am getting ready to wire a large floating concrete dock on a large project I have in Key West. The dock has arrived and has been installed. It consists of many 12ft long X 10ft wide sections. The top being pored concrete with man holes in each section and the remaining is foam. The dock has cast in place (20) 2 1/2 inch conduits that each goes to an individual large boat slip pedistal. This is large power. I have (4) 800 amp, 1phase panels feeding these 20 pedistals. My problem is that the floating dock is in these 12 ft sections. They are all bonded together from the sides so that the dock is one piece and no one section can float higher or lower than the other. From the top the concrete finish between the sections just looks like an expansion joint. One foot down, after the concrete pour, the foam begins and there is a 5 inch gap between the sections. All the 20 conduits line right up end to end but 5 inches apart. The dock manufacturer is claiming that on 99% of their docks the electricians use THWN and just bridge the 5 inch gap with the wire. It is unseen and not subject to damage. I have already run this by the inspector and he frowning at the idea. Now I have to sell him on it. "G" cable is out of the question because the outside diameter of the large cable is 2.39 an will not go in the 2 1/2 inch conduits. I can find nothing in the code. I would certaintly appreciate any feed back I can get.

Thanks
Steve Simpson
Simpson Electric LLC
 
Simpsonelectric said:
The dock manufacturer is claiming that on 99% of their docks the electricians use THWN and just bridge the 5 inch gap with the wire.
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310.13 Conductor Constructions and Applications.
Insulated conductors shall comply with the applicable provisions of one or more of the following: Table 310.13, Table 310.61, Table 310.62, Table 310.63, and Table 310.64.

These conductors shall be permitted for use in any of the wiring methods recognized in Chapter 3 and as specified in their respective tables.
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Basiclly that is saying THWN has to be in a raceway.


300.12 Mechanical Continuity ? Raceways and Cables.
Metal or nonmetallic raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets.
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ultramegabob said:
what type of conduit did they use? is it in embedded in concrete or foam?
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Thank you all for your replies. It is schedual 40 white plumbing pipe that is just below the concrete. You should see this mess. You open the man hole and you see 20 conduits stacked 10 and ten on top of each other that run clean through. The man hole is not big enough and there are conduits that are just barely visable on each side. You have to take a saw and cut the conduits off on each side ( I was making the cuts so I can at least put male adapters and bushing on each side for the feed through of the wire) of the man hole and dig in the foam to access the buried conduits and the conduit that 90's out and up to the pedistal.

Steve Simpson
 
kkwong said:
what about short sections of LTFMC or LTFNC?

Edit to add: Between the docks.
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I thought about putting a diver in the water but there is no way to get you hand up 2 ft into that 5 inch gap much less do any work. I'm going to have to use sections of 1/2 inch PVC as a fish tape.

Steve Simpson
 
augie47 said:
wrestled with dock wring more than once. ususally ended up with type W cable and often with some circuits along side and not in the "provided" conduits.
Here are two previous threads which may shed some light on your subject:

http://forums.mikeholt.com/search.php?searchid=774154

http://forums.mikeholt.com/showthread.php?t=87545&highlight=docks
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I have a call into the wire manufacturer to get the OSD of the W cable. But still what chance do I have to put a cable in a 2 1/2 conduit that has (3) 250 MCM and the ground and all that outside jacket.

Thanks
Steve Simpson
 
Simpsonelectric said:
I thought about putting a diver in the water but there is no way to get you hand up 2 ft into that 5 inch gap much less do any work. I'm going to have to use sections of 1/2 inch PVC as a fish tape.

Steve Simpson
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Are the floating sections just bolted together? Maybe you can unbolt a section, put in some sealtite, bolt it back together?

White PVC? Will electrical connectors fit white PVC? Is that even rated for use as a raceway? (I'm not being harsh, I really don't know. I thought it was only for plumbing but again what do I know!?)
 
jerm said:
Are the floating sections just bolted together? Maybe you can unbolt a section, put in some sealtite, bolt it back together?

White PVC? Will electrical connectors fit white PVC? Is that even rated for use as a raceway? (I'm not being harsh, I really don't know. I thought it was only for plumbing but again what do I know!?)
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Well you know alot my friend. Last time I checked plumbing conduit is not electrical conduit. The connectors would fit Schedual 40 and not thin wall. I'm going to use all of you professional posts as a case to the GC and the developer, that already agree with me, that they got sold a 600K POS. I'm just waiting for the electrical inspector to speak the words " UL Rated Assembly"

Thanks
Steve Simpson
 
Steve,
it's been a number of years so this is fuzzy.
I recall some multiconductor W being installed on hanger alongside the underside of the dock.
Also, it might be worth your while to look at W feeder cable (individual)
check diameter and ampacity. I beleive you may find one possible answer is to use that and marine pedestal units that you can "feed thru" similar to a RV park. IMHO, Art 555 will allow you to use W cable thru the white PVC (see 555.13(B)(4)

Its somewhat of an engineering nightmare taking into account ampacities, voltage drop, demand factors. The few with which I was involved were almost not worth the time spent planning.
 
For what its worth i did similar install about 13 years ago in Naples FL.Not sure why it passed but had same white pvc and we used thwn.Love KW wish i was there,do you need help ?As far as legal that is gonna be between the ahj and you.Is this dock being done by Bellingham ?
 
ultramegabob said:
could you post some pictures, I would love to see what your dealing with.
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I'll bring my camera down next week and post the pictures so you can all see the horror and scratch that smart spot:) This is really a great site. I'm glad I joined up.

Steve Simpson
 
Simpsonelectric said:
I'll bring my camera down next week and post the pictures so you can all see the horror and scratch that smart spot:) This is really a great site. I'm glad I joined up.

Steve Simpson
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I look forward to your pictures Steve. I'm glad you joined too, welcome!
 
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