Marina Calculation- 555.12

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220wire

Member
I dont quite understand why 555.12 is in the code. I saw mweaver had a great post on demand factor for a marina.
So I have a marina that has 9 individualy metered peds with 120v/30a plugs per 100a circuit. The furthest peds are about 480-600ft from the MDP. The drawings show 4/0 for the first 250' then 1/0 for the remainder. How could this be anywhere close to an NEC calculation?
 
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hardworkingstiff

Senior Member
Location
Wilmington, NC
A little more info would be nice. I read you have 9 pedestals, but I'm not sure if you have 1 30-amp receptacle per pedestal or 2. If you have 2 per pedestal, then I'd say you are correct and it's not NEC compliant. If you had 1 per pedestal and the MWB feeder was divided to 5 receptacles on A-phase and 4 receptacles on B-phase, then if you put a 150-amp breaker in for OCP on the feeder I believe you would be NEC compliant.

What do you have?
 
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hardworkingstiff

Senior Member
Location
Wilmington, NC
One more tip, it often works out less expensive in materials if you use smaller feeder sizes and more circuits. Seems you get more amps/pound of copper in smaller cables. Labor is more because of more home runs, but it takes a little bit more labor to handle larger wire.
 
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220wire

Member
2- 30a/125v receps per pedestal and about 9 peds per 100a circuit. On one dock there are 17 peds with 50/30a fed with 4/0's then reduced to 2/0's all on one 100a breaker. I just dont see how any calculation could come up with that number. Granted the summers here are mild, but I have seen a 45' boat burn up a 50a 250/125v plug because of the 2 ice makers, water heater, electric heaters, etc. that were running.
 
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hardworkingstiff

Senior Member
Location
Wilmington, NC
220wire said:
2- 30a/125v receps per pedestal and about 9 peds per 100a circuit. On one dock there are 17 peds with 50/30a fed with 4/0's then reduced to 2/0's all on one 100a breaker. I just dont see how any calculation could come up with that number. Granted the summers here are mild, but I have seen a 45' boat burn up a 50a 250/125v plug because of the 2 ice makers, water heater, electric heaters, etc. that were running.
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I agree with you. :)
 
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