Boat lift question

Tbizzelmd

Member
Location
Crofton,md
I am running power from a sub panel to the end of a pier. The run is 125'. How far away does a disconnect have to be from the motor? The motor is 240 and 20 amp breaker. I'm running 4 #10 THHN in a 3/4 PVC. What would the best disconnect to use?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Thanks or the quick response! What disconect would you use for this application. Would a 240v switch be against code?
2 things to watch. If you are upsizing the ungrounded conductors to #4 then you must run a #4 equipment grounding conductor. Not sure what the amp of the motor is but as long as the switch is rated 115% of the fla then you are fine. In many cases a dp switch is just fine.
 

edward

Senior Member
2 things to watch. If you are upsizing the ungrounded conductors to #4 then you must run a #4 equipment grounding conductor. Not sure what the amp of the motor is but as long as the switch is rated 115% of the fla then you are fine. In many cases a dp switch is just fine.
He is using 4 #10s.

But if he was #4 then the EGC has to be #4 as well.
 

Tbizzelmd

Member
Location
Crofton,md
Thank you guys, your a big help. Going to go through this code book and find articles so I can know for the next time. Why can't they make uf with an insulated ground?! Be a lot easier than having to run pipe all underneath the pier.
 

GoldDigger

Moderator
Staff member
Kwired.. In order for the boat lift to be gfi protected wouldn't u need that neutral?
A GFI for an L1-to-L2-only load does not have to have either a neutral or a ground to operate. Whether the neutral wire needs to be run to the equipment (or at least to a disconnect) can be considered separately from that.
 

kwired

Electron manager
Location
NE Nebraska
Kwired.. In order for the boat lift to be gfi protected wouldn't u need that neutral?
Depends on the location of the GFCI. You don't need a neutral conductor on the load side of a GFCI if there is no load that will utilize that conductor, but you will need one run with supply conductors to the GFCI as the GFCI device typically needs the "incoming" neutral to function properly.

That said I don't see any requirement for "class A" GFCI protection for personnel. Only place that is mentioned is for 15 and 20 amp 125 volt receptacles, otherwise 555.3 requires ground fault protection not exceeding 100mA. Now it may be popular choice to use a class A GFCI for such installs anyway and they would still be code compliant.

Now 555.3 is not all that clear about if the ground fault protection needs to be on the shore or if it can be on docks, piers, etc.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
If the 10 wire is run to a sub panel then a neutral will be needed for the 120V gfci's that may be at the boat dock area. Am I assuming correct that you will have a panel?
 

kwired

Electron manager
Location
NE Nebraska
Cause that is how they are made?

Some looking around and I don't know for certain if they would work without a neutral, but instructions say they must be connected to a neutral.

According to information from Square D on their GFCI breakers (GFCI info starts on page 9) you must connect the neutral pigtail on the 2 pole units. The basic schematic they show in this document suggests that it possibly may still work without a neutral but the test button would not complete the test without a neutral.
 

GoldDigger

Moderator
Staff member
Cause that is how they are made?

Some looking around and I don't know for certain if they would work without a neutral, but instructions say they must be connected to a neutral.

According to information from Square D on their GFCI breakers (GFCI info starts on page 9) you must connect the neutral pigtail on the 2 pole units. The basic schematic they show in this document suggests that it possibly may still work without a neutral but the test button would not complete the test without a neutral.
They chose to place the test current resistor from neutral to one phase so that they could use the same button and resistor value that they use for the single pole units. There is no reason they could not have used a resistor with twice the ohm value and twice the power rating and connected it between L1 and L2. But they did what they did. So it is a manufacturers' decision rather than a physical law that requires the neutral pigtail connection.
And of course if there is a current carrying neutral to the load, it must pass through the current coil in the GFCI. That part is a physical law.
I cannot find any fault in your use of "typically" since it is hard to get more typical than SquareD. :)
 

mgookin

Senior Member
Location
Fort Myers, FL
Strongly suggest putting a GFCI breaker in the panel on shore before those conductors go over water. Kids & adults get killed very often by dock wiring when they're in the water. Just putting GFCI receptacles at the lift does not eliminate the hazard.
 

Tbizzelmd

Member
Location
Crofton,md
I have a 100 amp main lug sub panel at end of pier fused @ 50 amps from the house. I was planning on the boat lift and rec on the pier will have gfi breaker. I have a 10/3 uf pulled to the boat lift now so if I switch it over to 240 and it does not need the neutral I should be good. I will tape up the red green. And install a 240 v switch. it Is a private pier btw
 
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