I am preparing schematic engineering for a rather large floating marina. Based on NEC load calcs and distances (1000 foot long piers)15 kV distribution fits.Docks are concrete with conduits inside. All pad mount equipment is suitable for pedestrian contact. Looks just right from a power standpoint but was wondering has anyone seen this done before in a floating marine application.Utilazation voltage is mainly 120/240 single phase with some 480/277.Next post topic will be special bounding, grounding(not earthing)as related to safety and corrosion.
15 KV Distribution for Floating Marina
- Thread starter bbb
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oliver100
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Re: 15 KV Distribution for Floating Marina
Salt and moisture are the enemy, provided that the marina is not on a lake. Stainless steel enclosures NEMA 4 and PVC coated steel conduits are the standard specifications for the high span bridges of NYC. Cathodic protection must be addressed. But I think it should be of concern to the structural guys.
Marine grade equipment should be the norm. Lighting, wiring devices etc. IEEE and ABS (American Bureau of Shipping) have developed standards and specifications.
Should the HV distribution be grounded? I would use delta/Y transformers with ground fault alarm on the high voltage side. On the secondary side follow the NEC. I do not know if the installation would require the local inspector to show up.
Salt and moisture are the enemy, provided that the marina is not on a lake. Stainless steel enclosures NEMA 4 and PVC coated steel conduits are the standard specifications for the high span bridges of NYC. Cathodic protection must be addressed. But I think it should be of concern to the structural guys.
Marine grade equipment should be the norm. Lighting, wiring devices etc. IEEE and ABS (American Bureau of Shipping) have developed standards and specifications.
Should the HV distribution be grounded? I would use delta/Y transformers with ground fault alarm on the high voltage side. On the secondary side follow the NEC. I do not know if the installation would require the local inspector to show up.
rcwilson
Senior Member
- Location
- Redmond, WA
Re: 15 KV Distribution for Floating Marina
Any concerns about oil-filled pad-mount transformers over the water? Using dry-type or cast resin transformers would solve that.
Any concerns about oil-filled pad-mount transformers over the water? Using dry-type or cast resin transformers would solve that.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Re: 15 KV Distribution for Floating Marina
FYI,
NFPA 303, 2000 Edition reads:
3.4.2 Primary power of 600 volts maximum shall be carried to piers where design considerations require more than 250 volts maximum due to load requirements .........
3.4.3 Primary power, when introduced in excess of 250 volts phase to phase, shall be transformed to reduce the marina or boatyard system to be not in excess of 250 volts phase to phase.
Exception: 600 volts maximum shall be permitted to be used for a yards' distribution system where the use of the system has been approved by the authority having jurisdiction.
FYI,
NFPA 303, 2000 Edition reads:
3.4.2 Primary power of 600 volts maximum shall be carried to piers where design considerations require more than 250 volts maximum due to load requirements .........
3.4.3 Primary power, when introduced in excess of 250 volts phase to phase, shall be transformed to reduce the marina or boatyard system to be not in excess of 250 volts phase to phase.
Exception: 600 volts maximum shall be permitted to be used for a yards' distribution system where the use of the system has been approved by the authority having jurisdiction.
Re: 15 KV Distribution for Floating Marina
NEC 2002 Article 555.4 has similar max voltage for Distribution.
The demand calc for one pier is 1508kva or 1815 amps at 480 3ph.on a 1000 ft long pier.
If distribution is 120/240 can feeder voltage and feeders be above 600 volt. I think it must in this case.
NEC 2002 Article 555.4 has similar max voltage for Distribution.
The demand calc for one pier is 1508kva or 1815 amps at 480 3ph.on a 1000 ft long pier.
If distribution is 120/240 can feeder voltage and feeders be above 600 volt. I think it must in this case.
Re: 15 KV Distribution for Floating Marina
I got no clue if there is an EPA law or restriction to it. Some form of oil containment would be needed I'm guessing. I would say that a regular dry-type would be a no-no even with the proper enclosure, especially if on salt water. The cast resin would be a much better choice, it will last longer. Maybe a TENV transformer might be an overkill but ultimately the best choice.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Re: 15 KV Distribution for Floating Marina
Another thing I'd be curious about is how are you going to make the transition from underground on shore wiring to the floating dock wiring. You need have a cable capable of withstanding the continuous tidal movement (the transition cabling is often submerged twice per day so the cable needs to have a "wet" rating). I don't think they make a 15kv cable rated for this (maybe they do). The NEC recognizes type W cable which works very well on floating docks and has a 2,000 volt rating.
Around here, the AHJ has taken note of NEC 555.13(B)(4)(b) to mean you must have a J-box at one end of the ramp. A real pain in the A$$.
I sure would like to know how you wind up designing this. I have issues with this type of stuff all the time.
I don't think you can design this way and stay in compliance with the NEC or NFPA guidelines.
Another thing I'd be curious about is how are you going to make the transition from underground on shore wiring to the floating dock wiring. You need have a cable capable of withstanding the continuous tidal movement (the transition cabling is often submerged twice per day so the cable needs to have a "wet" rating). I don't think they make a 15kv cable rated for this (maybe they do). The NEC recognizes type W cable which works very well on floating docks and has a 2,000 volt rating.
Around here, the AHJ has taken note of NEC 555.13(B)(4)(b) to mean you must have a J-box at one end of the ramp. A real pain in the A$$.
I sure would like to know how you wind up designing this. I have issues with this type of stuff all the time.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: 15 KV Distribution for Floating Marina
I don?t think you can get past this requirement, and I don?t think you should try. Not all of the 1815 amps will have to travel all of the 1000 foot distance. Set the system up with 480V ? 120/240V, single phase transformers, in sets of three (i.e., to balance the phases). Put one third of the 1815 amps through three transformers at the 100, 200, and 300 foot distances from the head of the pier. Put a second third of the 1815 amps through three transformers at the 400, 500, and 600 foot distances from the head of the pier. Put the final third of the 1815 amps through three transformers at the 700, 800, and 900 foot distances from the head of the pier. A pier that needs that much amps will certainly have enough room within the concrete pier structure to allow you to run that much copper.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Re: 15 KV Distribution for Floating Marina
If you can get the power company to deliver a 600 volt service, you can get an extra 25% of power with the same copper. Most of them tell me they won't deliver that voltage because it is a special voltage.
If these are the docks I'm thinking of, they are not very "wiring" friendly (other than providing a raceway).
If you can get the power company to deliver a 600 volt service, you can get an extra 25% of power with the same copper. Most of them tell me they won't deliver that voltage because it is a special voltage.
If these are the docks I'm thinking of, they are not very "wiring" friendly (other than providing a raceway).
Re: 15 KV Distribution for Floating Marina
I worked on a couple jobs similar to what you are doing. ~800ft docks. Used Type W cable, 480V Delta and stepped down where we needed it. I left the co. after the design and before the construction so I can't tell you how it worked out. Fun job to work on though. Best of luck.
I worked on a couple jobs similar to what you are doing. ~800ft docks. Used Type W cable, 480V Delta and stepped down where we needed it. I left the co. after the design and before the construction so I can't tell you how it worked out. Fun job to work on though. Best of luck.
Re: 15 KV Distribution for Floating Marina
Thanks for the input.
Oil definitely must be addressed.
Small quantity of seed oil typically easy to address large quantities different story
Cooper Power Systems has good info posted on their website with EPA references.
Also 550.30 has well written definition of Distribution System.
Thanks for the input.
Oil definitely must be addressed.
Small quantity of seed oil typically easy to address large quantities different story
Cooper Power Systems has good info posted on their website with EPA references.
Also 550.30 has well written definition of Distribution System.
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