2020 NEC 555.5

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The intent is to limit the voltage of the conductors that are on the pier. The second part is a lot like the "supervised industrial location" rule that are scatter throughout the code. It permits higher voltages on the piers under the specified conditions.
555.5 Maximum Voltage. Pier power distribution systems shall not exceed 250 volts phase to phase. Pier power distribution
systems, where qualified personnel service the equipment under engineering supervision, shall be permitted to exceed 250 volts but these systems shall not exceed 600 volts.
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The substantiation for the change was:
This PI is the work of an independent working group comprised of the following members: Thomas Domitrovich, Keith Lofland, Ken Bush, Donny Cook, Alan Manche, Larry Ayer, Jim Dollard, Alan Wyant, Paul Seff, Cliff Norton, Erik Gouhl, Tom Lichtenstein, Doug Lee, Dean Hunter, Wesley Wheeler, This working group was not commissioned by a code making panel nor the correlating committee. This public input limits the voltage on a pier to a maximum of 250V line to line unless the pier is under engineering supervision. This PI also limits the maximum voltage to 600V instead of 1000V. Marinas are not using 1000V and nor should these locations exceed 600V. Due to the increased hazards when in a marina environment, limiting the voltage of equipment on these structures where engineering supervision is not present is important from a safety perspective as these higher voltages carry with them special equipment and other challenges
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So with marinas it is very common To have a 480 Volt service on shore to feed Step down transformers and Distribution panels at 208 Volts to provide shore power to boats or floating buildings.

Has this went away? If so that is a huge change. A very expensive change.
 
210.19(B)(2) Supervised Installations.
For supervised installations, branch-circuit conductor sizing shall be permitted to be determined by qualified persons under engineering supervision. Supervised installations are defined as those portions of a facility where both of the following conditions are met:
  1. (1)
    Conditions of design and installation are provided under engineering supervision.
  2. (2)
    Qualified persons with documented training and experience in over 600-volt systems provide maintenance, monitoring, and servicing of the system.
 
In my opinion, it would be a very rare marina that meets the supervised installation rule. To my that means qualified electrical people on site 24/7.
 
Yes this is a big change indeed.
I would go to to 220Y/127 or 225Y/130.
Why?
  • All the loads are single phase
  • Voltage drop is usually high on the 30A 120 cords.
  • Since there are no vessels designed for 208 shore power and coast guard specs frown on powering a 240V system with 208 (yes I know its probably fine).
  • They also allow 30A 115V to be between 110 and 130V.
 
riverman said:
So with marinas it is very common To have a 480 Volt service on shore to feed Step down transformers and Distribution panels at 208 Volts to provide shore power to boats or floating buildings.

Has this went away? If so that is a huge change. A very expensive change.
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Just keep the 480 volts away from the piers. If you have long distances and/or higher capacity loads that make 480 volts favorable, run main distribution to your 208 volt transformers located close to but not on the pier or group of piers it serves.
 
If you supply a fancy yacht (or even a large RV) 120/208 clearly label the receptacles and be prepared to be blamed for anything and everything, they tend to expect '110/220'.
Also keep in mind there is a common device they use merge the two 30A receptacles when there is not '220':
dock-recept.jpeg
 
tortuga said:
If you supply a fancy yacht (or even a large RV) 120/208 clearly label the receptacles and be prepared to be blamed for anything and everything, they tend to expect '110/220'.
Also keep in mind there is a common device they use merge the two 30A receptacles when there is not '220':
View attachment 2551609
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Can't speak much about marinas as I haven't really done electrical work on any. I have never seen an RV with anything that is 240 volt (that wasn't some DIY add on anyway) If it has a 50 amp supply plug it just has more loads but they are all still 120 volt loads.
 
kwired said:
Can't speak much about marinas as I haven't really done electrical work on any. I have never seen an RV with anything that is 240 volt (that wasn't some DIY add on anyway) If it has a 50 amp supply plug it just has more loads but they are all still 120 volt loads.
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Interesting that makes sense, I see these mega RV's with washers/dryers and minisplits and have to wonder if its all 120V.
 
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