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555.3

3225 Views 6 Replies 4 Participants Last post by  hardworkingstiff
Helo,
I'm a residential electrician bidding on a small 8 slip marina. Reading the short chapter on marinas


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555.3
Ground-Fault Protection
The main overcurrent protective device that feeds the marina shall have ground fault protection not exceeding 100 mA. Ground-fault protection of
each individual branch or feeder circuit shall be permitted as a
suitable alternative.

This seems quit clear all feeders shall be gfci protected but knowing all marinas and boats have some voltage leak issues it seems as though "nuisance" trips going to be a recurring issue. All the marina in the area have no such protection however the article is new to the 2013 nec. Any help would be greatly advised before I order a 200 amp 3 phase gfci breaker
F Arnold MI. license 61-13412
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GFCI is normally considered personnel protection and has a trip threshold of about 5 ma. GFP is considered equipment protection and has a higher threshold.

IMO, you would be making a mistake to install a 5 ma main protection device in a marina because of the nuisance tripping you mentioned.

Since you are installing a 3-phase service, I'm going to assume all of your receptacles for shore power will be no more than 30A. In that case, IMO you are better off using the exception and installing individual circuits to each slip (you could use a GFCI breaker). That way an offending boat will not cut off the whole marina and you will know where the offending boat is. Remember though, there are limits to the length of conductors for some GFCI breakers (I think 200 - 250' comes to mind).
 

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Discussion Starter · #4 ·
Thanks to all

I found a product called marina gaurd. The fault current is user programmable so I can set it at the code required 100ma. It utilizes current tap transformers to trip relays so each pedestal can be placed on its own "relay". Correct on the typo 2011 is correct apologies about that. I have also spoke to other harbor masters that stated low volt 3 phase creates problems with a lot of boats power management systems, many complaints about "low voltage" alarms. So I'm bidding it as a single phase service. Thanks to all that replied. Nice to know there is help when you need it.
 

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I found a product called marina gaurd.
I like that product, but have never installed it. If this is a competitive bid with no specs, you will have to sell your price.

To use that product, you will have to order shunt trip breakers for every branch feeder. My guess on the cost per feeder for for CTs and shunt trip options is a few hundred dollars. You also have the problem that if the control power is lost for the shunt trips your system will not function properly.

What size receptacles are being called for on the slips, 30, 50?

The marina manager is correct, if you feed a 50A receptacle from 2 phases of a wye service the boats will not like it, it is also a code violation (555.19(3) ).

Good luck with this job, I love wiring marinas. Come back with any new questions.

What wiring method are you using?

Are these floating docks?
 

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The Power Post I used in a marina had 50 and 30 on same post . Could have a 20 also .




Pete
I'm doing the electrical work for a marina that is re-configuring their slips. Some of their existing pedestals have 100-amp single-phase power and 50-amp receptacles on the same pedestal. It's pretty common to have a 50 and 30 on the same pedestal if the slip size will accommodate boats right in the range where they go from needing a 30A to a 50A (that's probably in the 40-45 foot slip range).

They also had 3-phase power available for the 100' slips. I remember when this project was being done in 2006, the GC told them they would never use the 3-phase power, and he was right, they maybe used it once in 8 years.
 
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