Boat dock motor tripping GFCI outlet

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JFjesse

Member
I have shore power with 120 volt GFCI breakers feeding 4 seperate 120 volt 12 amp boat lifts. I am getting speratic tripping on the breakers. I have recently replaced the wiring, breakers etc. I have hipot tested the wiring and motors. All motors megged out at 220 MOhms and the wiring is good. Any advice?

Jesse
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
is each lift on a sperate circuit? what is the load when a boat is being lifted?
 

JFjesse

Member
I have shore power with 120 volt GFCI breakers feeding 4 seperate 120 volt 12 amp boat lifts. I am getting speratic tripping on the breakers. I have recently replaced the wiring, breakers etc. I have hipot tested the wiring and motors. All motors megged out at 220 MOhms and the wiring is good. Any advice?

Jesse

Each motor is on a dedicated circuit back to the shore panel with dedicated neutrals. The load is 12 amps under load @ 120 volts.

The distance from shore power to the motor outlet is 300 feet. I have heard that it is possible that the GFCI breaker is getting a different voltage on the hot going out versus the neutral return and that could be the problem. Anyone care to comment please....
 
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Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Each motor is on a dedicated circuit back to the shore panel with dedicated neutrals. The load is 12 amps under load @ 120 volts.

The distance from shore power to the motor outlet is 300 feet. I have heard that it is possible that the GFCI breaker is getting a different voltage on the hot going out versus the neutral return and that could be the problem. Anyone care to comment please....

Welcome to the forum.

I think you need to protect the electical circut as per your installation so gfci outlets are probably not an option. You could do this as a test. Some breakers brands will let you know if the trip is a ground fault or overcurrent.
What is the current draw under load?
 

JFjesse

Member
Welcome to the forum.

I think you need to protect the electical circut as per your installation so gfci outlets are probably not an option. You could do this as a test. Some breakers brands will let you know if the trip is a ground fault or overcurrent.
What is the current draw under load?

The amperage under load is 12 Amps @ 120 volts. I am getting 2 motors tripping one tiome and the other two motors will trip the next time. All neutrals have been verified to be matched with the circuit conductor.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
just thinking - do you have a true RMS meter? You may want to try to check the nuetral and the ground for current when under load. Do you have another load you can try on the circuit?
 
Location
Virginia
I would be curious to know what wire size you ran 300' to the motors with? Is it possible we are seeing a voltage drop issue due to a large resistance both to the motors and back to the panel GFCI breakers?

My Father-in-Law had a similar set up. Instead of running circuits off of GFCI breakers at the panel directly to the motors, we ran to disconnects that fed GFCI receptacles at the dock for the lift motors.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
I have heard that it is possible that the GFCI breaker is getting a different voltage on the hot going out versus the neutral return and that could be the problem.
That is not the issue here. There is always a difference in voltage between the hot and neutral. A GFCI device only looks at current. A difference in current between the "hot going out" and the neutral return will trip the GFCI.

The distance from shore power to the motor outlet is 300 feet.
That may be your problem. You didn't say, and I don't know if you could tell anyway, whether the breaker tripped because of a detected ground fault or because of an overload. But I suspect it is an overload. I calculated a voltage drop of 12%. With the voltage being that low, the motor will draw a current that is much higher than normal. That could cause the occasional trip. It would be a random event that would depend on many factors, including weather conditions. A motor might trip one day and not another day.


My suggestion is that you look into options for refeeding the circuit. I calculated that you would have to go with #6 wire, to get the voltage drop below 3%.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Voltage drop I would think would think would need to be over 30% for the breaker to trip from overcurrent. I still would check voltage with a true RMS amp meter under load in order to rule this out.

I would do a check as stated earlier with a regular breaker and local GFCI. You could also resort to a EPD style GFCI and be dedicated to the motor only no other outlets duplex or otherwise if its a gfi issue.
 

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
had a similar issue once.



the hoist bearings were low on grease. it was putting a strain on the motor.
 
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