GFCI to a boat dock

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wmeek

Senior Member
Location
Texas
Occupation
Electrician
A customer has a 10/3 uf cable from house to boat dock on a lake that has 2-20A 1p circuits. Can you use a
2p20A Gfci breaker for these two circuits for protection to the boat dock.
 

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
by a 10/3 UF cable do you mean 3 conductors and a ground? or 2 conductors and a ground?
10/3 would mean 2 conductors and a ground in rubber cord. For some reason rubber cord is labeled that way while nm, uf, etc all ignore the equipment grounding conductor when labelling
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
Not really sure if its UF are not i do know it has black, Red, white , and green . Thats why i was wanting to see if i could i use a 2p 20A Gfci breaker to protect the two circuits.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Not really sure if its UF are not i do know it has black, Red, white , and green . Thats why i was wanting to see if i could i use a 2p 20A Gfci breaker to protect the two circuits.

I think you are OK as far as the GFCI itself goes.

However, I would point out that if the cable goes a long way it may well have enough leakage that the GFCI could potentially trip more easily than you might like.
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
Is a GFCI required from panel to dock. If not i could install gfci at dock to protect circuits
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I would be cautious here. Not sure why you are installing a gfci on the feeder unless this dock qualifies under art. 553. If you use a standard gfci my guess if that you may have issues with it tripping-- depending on what you are feeding. I have a customer that has a boat that will not run on a 4-6ma nor a 30 ma gfci. He needs a 100 ma gfci which will cost a $1000 or so. If you are just feeding lights and a receptacle you may be fine
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
Its not a floating building so my guess it woud not fall under Art. 553. This is on a residential property. If im not required to install gfci on the branch circuit to dock , i would then just install two gfci for each circuit at dock. Each circuit will have a 3/4 hp 120v Boat motor. The motors came with gfci on end of plug. They have been running fine
 

GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
I would be cautious here. Not sure why you are installing a gfci on the feeder unless this dock qualifies under art. 553. If you use a standard gfci my guess if that you may have issues with it tripping-- depending on what you are feeding. I have a customer that has a boat that will not run on a 4-6ma nor a 30 ma gfci. He needs a 100 ma gfci which will cost a $1000 or so. If you are just feeding lights and a receptacle you may be fine
Would an isolation transformer or galvanic isolator on the boat work and cost less,?
 

Dennis Alwon

Moderator
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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Would an isolation transformer or galvanic isolator on the boat work and cost less,?


He actually has a $3000 isolation transformer but is hoping for a cheaper alternative :thumbsup: I believe there is a 50 amp feeder down to the marina slip--- I have not been there as others have been dealing with it. He said he replaced his stove, heaters, refrig, etc and nothing helped. The ec bought a 30 ma gfci and that didn't help either-

Manufacturers told him he needed a 100 ma or it would not work. They may have also suggested an isolation transformer to him because he said he has one
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Is 10/3 UF anything other than flat, grey cable? Serious question as I dont think Ive ever seen smaller gauge UF any other way.

That is the only way I have seen it but it could be white also.

BTW, in my other post the isolation trany has to be Marine rated hence the extra cost.
 

domnic

Senior Member
Occupation
Electrical Contractor
Gfci

Gfci

I would be cautious here. Not sure why you are installing a gfci on the feeder unless this dock qualifies under art. 553. If you use a standard gfci my guess if that you may have issues with it tripping-- depending on what you are feeding. I have a customer that has a boat that will not run on a 4-6ma nor a 30 ma gfci. He needs a 100 ma gfci which will cost a $1000 or so. If you are just feeding lights and a receptacle you may be fine

why would a gfci a issue on a feeder ? a 100ma gfci to protect what ?
 

fmtjfw

Senior Member
why would a gfci a issue on a feeder ? a 100ma gfci to protect what ?

To protect the cable and anything on the line side of the on-dock GFCI's. Water and electricity don't mix, especially if someone is going to swim, or fall in, the water when there is leakage from the electrical system. It kills people every year.

And the electricity doesn't know if the water falls under 555 or is around a residential dock.
 
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