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Question for guys with floating docks


ckhokiehi

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My parents recently finished building on Norris in Tennessee, where the dock may raise or lower with the water 15-20ft.  For those of you who have floating docks that float in or out, how are you running electricity out to the dock?   We've been keeping it pretty ghetto, running an extension cord from the box on the shore out to the dock.  Clearly that's not sustainable to run the lift, water pump, fridge, stereo, etc..

I'd like to keep an install pretty clean, and not have a wire hanging in the air out to the dock. 

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Only pic I have of dock in question, which is a little old.  Prefer to not have anything attached to roof

IMG_2437-1_zpskuufelec.jpg

 

Edited by ckhokiehi
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First thing to do is ditch the extension cord before somebody gets killed.  Next call a qualified electrician that can run cable rated for underwater use.

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I ran everything in outdoor conduit under the walkway. I used a flexible hose in the areas that move. Only ran a couple of gfi outlets for lights and the lift. No issues in the past 13 years

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13 minutes ago, SkiingPT said:

First thing to do is ditch the extension cord before somebody gets killed.  Next call a qualified electrician that can run cable rated for underwater use.

Clearly the extension cord is a temporary thing, but the box down by the water has it's own breaker built in (aside from the breaker at the house panel), which trips even if it starts sprinkling.

To your second point, an underwater cable is fine as long as we don't have 10s of feet of cable sitting on the ground when the water is down

Edited by ckhokiehi
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* Edited to add detail since this topic seemed to generate interest *

My buddy has a place @ norris.  For his new dock we installed a 2000W/400W peak inverter, house battery and a solar panel and charger.  Runs the lift, LED lights, stereo, etc.  Awesome and no cords to electrocute swimmers and costs less than an electrician and wiring.  The issue with Norris as the OP mentioned is the huge swing in lake levels during the year.  It's a job to keep the winches set to keep the docks in the right place.  Adding power makes the job that much more of a challenge.

A Rubbermaid plastic storage cabinet was used to hold the gear, as well as other stuff for the dock.  We mounted this solar panel to the side of the storage cabinet that faces the most sunlight - we added spacers at the bottom mounts to tilt it slightly skyward.  He didn't want to drill holes in the new roof of his big $$ dock either:

http://www.harborfreight.com/15-watt-12-volt-solar-panel-96418.html

We used this voltage regulator:

http://www.harborfreight.com/7-amp-solar-charge-regulator-96728.html

We used this inverter:

http://www.harborfreight.com/2000-watt-continuous4000-watt-peak-power-inverter-60432.html

He's using this lift to hold his Supra Launch 22V:

http://www.boatlifts-floatair.com/item/1031

The key for performance is a beefy battery.  Harbor freight sells a little sealed 12V battery for cheap.  We tried this at first and when we fired up the boat lift air pump, the inverter alarm went off after about 30 seconds.  The lift pump only consumes 7A at start-up (less after start) so the inverter has more than enough to power it.  But the battery was the issue.  Switching to a big marine battery (like you use to power a trolling motor for hours at a time) worked perfectly.

The other advantage of this set-up is you can use affordable 12V stuff.  Landscape lighting for dock lights, for example.  And you can use marine stereo parts for dock tunes if you want.  You can add batteries or go to a larger panel if you need more capacity.

Good luck!

 

Edited by EchelonMike
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1 hour ago, ckhokiehi said:

Only pic I have of dock in question, which is a little old.  Prefer to not have anything attached to roof

IMG_2437-1_zpskuufelec.jpg

 

I envy that dock... even without power.......

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Do not cut corners with dock electrical.

This is a family down the road from me. My brother in law was one of her poll bearers at the funeral.

http://www.today.com/health/after-tragedy-parents-raise-awareness-about-electric-shock-drowning-t93761

 

That said, it's really easy to stay safe as long as everything is done properly. Everything in conduit and plastic outlet boxes. Wire should never contact the metal dock frame. Everything has to be gfi. You need to run at least two gfis in series for every leg. Three will probably give you false trips I'm told but we rarely had false trips running two. I used a gfis breaker at the main panel and again at the sub panel. Even if it's wired correctly I'm told you can get residual current. Supposedly the fix to that is to have a "blocker" installed at the transformer by the power company. I've never had to do that so I'm not up on that portion.

I recommend a cutoff on the dock with easy access as well.

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1 hour ago, chris4x4gill2 said:

Do not cut corners with dock electrical.

This is a family down the road from me. My brother in law was one of her poll bearers at the funeral.

http://www.today.com/health/after-tragedy-parents-raise-awareness-about-electric-shock-drowning-t93761

 

That said, it's really easy to stay safe as long as everything is done properly. Everything in conduit and plastic outlet boxes. Wire should never contact the metal dock frame. Everything has to be gfi. You need to run at least two gfis in series for every leg. Three will probably give you false trips I'm told but we rarely had false trips running two. I used a gfis breaker at the main panel and again at the sub panel. Even if it's wired correctly I'm told you can get residual current. Supposedly the fix to that is to have a "blocker" installed at the transformer by the power company. I've never had to do that so I'm not up on that portion.

I recommend a cutoff on the dock with easy access as well.

Agree. Two GFCI in series. One on main panel in the house and then one for each circuit on the dock if there is a panel on the dock.  If no panel on the dock then one in the house and one at the shore end of the dock which can double as your disconnect. UF rolmex inside schedule 80 PVC conduit, and plastic flex conduit where needed. Not really expensive.  Recommend you not run 220 V with common.  Better to run two separate 110 V circuits.  If you use extension cords anywhere route them carefully to prevent abrasion and replace them every year.

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Here is some info from my notes.

 

 

 

From our Electrical Engineer here at work:

- a GFI breaker at the panel box at the house

- GFI breakers at the boat dock's panel box

- a GFI receptacle at the beginning of each series of receptacles

- PVC conduit (not galvanized).

 

 

 

 

From National Electrical Code:

Electrical Installation Requirements for Private Boat Docks 

For use by owner or resident of single family dwelling

Contact your local AHJ (Authority Having Jurisdiction) for an inspection prior to supplying power to the dock
Electrical Installation:
All electrical installations shall be in compliance with 2008 National Electric Code and as amended by AHJ

All conductors shall be insulated copper conductors approved for the conditions of use

Each docking facility requiring electricity shall be supplied by only one (1) set of feeder conductors from the residential house panel. One (1) single branch circuit can serve as a feeder conductor if it is connected to a feed through module GFI disconnecting means.

Overcurrent device(s) or disconnecting means designed to disconnect all electrical power supplying the docking facility shall be located onshore and within six (6) feet of the docking facility ramp it serves

The bottom height of the Overcurrent device(s) or disconnecting means shall be 42” above the dock walkway at the shore connection

A grounding electrode (in compliance with NEC) shall be installed the onshore overcurrent device(s) or disconnecting means.

An insulated grounding electrode conductor(sized in accordance with NEC, but not smaller than #6 AWG) shall be installed connecting the grounding electrode to the equipment grounding terminal at each onshore sub panel or disconnecting means enclosure(s).

An insulated equipment grounding conductor (sized in accordance with NEC, but not smaller than #12 AWG) shall be installed inside all conduit systems with the circuit conductors.

All conductors (Feeder & Branch Circuit) shall be sized for the overcurrent device protecting the conductors and shall be sized to not allow more than 3% voltage drop as recommended in NEC.

Conduits, boxes and fittings approved for the condition of use, shall protect all feeder and branch circuit conductors

All underground conduit systems shall be approved for the condition of use and shall comply with NEC.

All conduits shall be sized in accordance with NEC

Liquidtight Flexible Metal conduit(with grounding bushings) or Liquidtight Flexible Nonmetallic conduit with approved fittings shall be permitted where flexibility is required in a conduit system such as hinge points of ramps and floating structures subject to elevation changes due to changes in water levels.

All non-current carrying metal parts of docking facility such as metal piping, metal equipment enclosures, metal frames of the structure and ramps, ,metal swim ladders and other metals in contact with the water or may become electrically energized shall be electrically bonded to the equipment grounding system

A bonding jumper with a loop (Sized in compliance with NEC, but not smaller than #6AWG) shall be installed around all hinge points of metal ramps, floating structures and docks subject to elevation changes due to changes in water levels

All non current carrying metallic parts of the electrical system shall be bonded to the equipment grounding system (Panels enclosures, gutters, junction boxes, switch boxes, receptacle boxes, etc.)

All receptacle outlets shall be GFCI protected for personnel unless the outlet is for a dedicated purpose and installed in an enclosed area of the structure protected from the weather. All receptacle outlets shall be installed at least 36” above the finish dock surface or as approved by local AHJ.

All “Marine Shore Power outlets” shall be GFCI protected for personnel with a disconnecting means within 30 inches

All large metallic enclosures, such as panels, cabinets, cut out boxes, etc. installed in wet location areas, shall be installed with a minimum of ¼” air space between enclosures and supporting surface they are mounted on.

All electrical equipment installed within 8 feet vertically from the dock finish surface or exposed to the weather shall be suitable for wet locations and shall have weep holes

All electrical equipment installed below roofed open areas, protected from weather and installed above 8 feet from the dock finish surface shall be suitable for damp locations

All general use receptacle outlets shall be installed in weatherproof enclosures with ”In Use Type” weatherproof attachment plug covers

All general use switches shall be installed in weatherproof enclosures with weatherproof switch covers

All luminaries (lighting fixtures) installed exposed to the weather shall be suitable for use in wet locations. All luminaries (lighting fixtures) installed where protected from the weather shall be suitable for use in damp locations

All electrical equipment such as receptacle outlets, switches, junction boxes, lighting fixtures, etc. shall not be installed within 6 feet of any ladders attached to the docking facility

All metal ladders permanently attached to the docking facility shall be bonded to the equipment grounding system.

All metal ladders not permanently attached to the docking facility shall have means for bonding to the equipment grounding system

All conductors from the shore to the docking facility shall be protected from physical damage. Conduits shall be approved for the condions of use ( Weatherproof, Sunlight resistance, etc.)


Dock Wiring Inspection Checklist


Feeder from the main panel to sub panel shall be 4 wire for 240 volt system or 3 wire for 120 volt system and sized for the load. 
2. Conduit that is buried from the building to the sub-panel shall be schedule 40 PVC for underground use. 
3. Junction box on the outside of the building serving the dock shall be weatherproof. 
4. The feeder from the sub-panel to the dock shall be schedule 40 PVC (sunlight resistant) and must be liquid tight flexible conduit at all pivot points. 
5. The conduit from the J-box to the dock sub-panel or disconnect shall be sized for the conductors. 
6. The sub-panel shall be at the seawall next to the dock ramp and shall have a disconnecting means. 
7. All grounding conductors shall have continuous outer finish that is green including all bonding wires. 
8. The grounding conductors shall be connected to the grounding bus in the sub-panel and to the ground rod. Grounding Bus and Grounded Bus must be separated. 
9. A grounding electrode shall be in place. (At least 8 feet long and trade size of ½ inch). 
10. The grounding conductor shall be sized correctly for the circuit (minimum #6) and attached with a separate clamp directly to the grounding electrode. 
11. #6 grounding wire from the ground rod to the metal parts of the ramp with approved terminals. 
12. #6 grounding wire jumper shall be installed between all pivot points in the ramp, dock stiff arms, breakwaters, etc. 
13. All metal enclosure and exposed metal parts of the electrical system shall be bonded to the grounding bus with approved terminals. 
14. All metal parts, metal piping and all non-current carrying metal parts must be bonded to the panel board. 
15. All outlet receptacles shall be GFCI protected unless the outlet is a dedicated outlet in an enclosed structure. 
16. All general use outlet receptacles shall be a minimum 36 inches from the finished dock surface. 
17. All outlets dedicated for a piece of equipment shall be of the Marine Twist Lock type and GFCI protected. A disconnecting means must be within 30 inches of outlet or approved pedestal installation. 
18. All GFCI outlets receptacles shall work when tested. 
19. All cabinets and cutout boxes shall be a minimum of ¼ inch of airspace between the enclosure and supporting surface. 
20. All enclosures below 8 feet or exposed to weather shall be in weatherproof enclosures and suitable for wet locations with allowable weep holes. 
21. All fixtures above 8 feet and below a roof or overhang shall be suitable for damp location. 
22. All general use receptacles shall have an attachment plug cover (“in use” type). 
23. All switches shall be in weatherproof enclosures or cabinets. 
24. Receptacles, switch boxes and junction boxes shall not be within 6 feet of a ladder for the dock. 
25. Any metal ladder on the dock shall have #6 wire jumpers to dock frame from ladder base and to ladder if hinged (Frame can be bolted to dock frame). 

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36 minutes ago, chris4x4gill2 said:

ThaHere is some info from my notes.

 

 

 

From our Electrical Engineer here at work:

- a GFI breaker at the panel box at the house

- GFI breakers at the boat dock's panel box

- a GFI receptacle at the beginning of each series of receptacles

- PVC conduit (not galvanized).

 

Thanks for the info.

1 - done

2 - GFI at the box near the water, done

3 - most likely will be included once electronics are added to dock

4 - biggest question mark.  Clearly using PVC would be the best to run, but I am stumped as to the best way to achieve this with the water variability.  I essentially need a way for it to feed outward and recoil in while the water levels change

Edited by ckhokiehi
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Just now, ckhokiehi said:

Thanks for the info.

 

4 - biggest question mark.  Clearly using PVC would be the best to run, but I am stumped as to the best way to achieve this with the water variability.  I essentially need a way for it to feed outward and recoil in while the water levels change

What is your setup for the shore mount? Is it permanently mounted in one position or do you roll the walkway in / out to chase the water?

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2 hours ago, ckhokiehi said:

4 - biggest question mark.  Clearly using PVC would be the best to run, but I am stumped as to the best way to achieve this with the water variability.  I essentially need a way for it to feed outward and recoil in while the water levels change

Kind of depends on how much change in length you'll have.  A hanging length of plastic outdoor flex can work well if you can protect it from traffic (coolers, skis, etc.).   In your situation I would go from two 15 amp GFCI breakers on your house panel, get the circuits outside (buried UF rolmex) to a weather proof box with cut off switches by the gangway then 3/4" Schedule 80 (with flex where needed) with two 15 amp (14-2 UF) conductors to two GFCI outlets on the dock.  That should handle the lift on one and misc. stuff on the other.  Also suggest your pump (assume for washing?) be UL listed for submersion. Oh, and don't mount the cut off switch box to a live tree or anything like that :whistle:

NEC citation is nice but NEC tends to be so over the top as to be impractical.  Does anyone actually ground every piece of metal?  Your local inspector may or may not be understanding about strict adherence to the code so consider that before hiring a pro who will then get the inspector involved.  Maybe check with neighbors.  Most inspectors take a "don't ask, don't tell" approach as long as it's not too ghetto.  In other words, they don't go around looking for code violations - but if you call and ask them to come find some, they will.

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@chris4x4gill2Even out here in Cali I read about that. Tears came to my eyes when I read it. Sorry to hear it was so close to home for you.  

As an Electrical contractor and per @chris4x4gill2 post above.

PLEASE FOLLOW THE NEC!!!

The bonding at the hinge point is to maintain bonding throughout the dock. Without bonding at the hinge point, when rust begins, the bond will fail. 

We do not need anymore tragedies like mentioned above.

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1 hour ago, Sparky450 said:

As an Electrical contractor and per @chris4x4gill2 post above.

PLEASE FOLLOW THE NEC!!!

The bonding at the hinge point is to maintain bonding throughout the dock. Without bonding at the hinge point, when rust begins, the bond will fail. 

We do not need anymore tragedies like mentioned above.

X1,000,000

Electrical work isn't rocket science but at the same time, there is a reason electricians have to go to school and be licensed.  If life safety is involved then cutting corners should NOT even be considered.  

Always remember.  If, God forbid, someone is hurt and your installation is found to be sub standard you will be liable.  

Edited by ID AX
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11 hours ago, chris4x4gill2 said:

What is your setup for the shore mount? Is it permanently mounted in one position or do you roll the walkway in / out to chase the water?

gangplank is on wheels that roll up and down a concrete form which has ramps on the sides (for the wheels) and stairs down the middle.  Gangplank probably travels 15 feet vertically over the course of the year.

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2 hours ago, 95echelon said:

Have you called a local sparky? You cant be the first folks doing this.

We're definitely not.  Just aiming for a bit of a cleaner look, with nothing hanging out in plain sight.  Parents just got their boat down to the lake full time 2 weeks before Memorial Day, so we haven't been able to scope out as many of the neighbors setups as I'd like.

 

 

For all other posts, I appreciate the replies.  All of the electrical work was done by a fully licensed and recommended electrician, and has all passed code checks.  We currently have a cutoff box not far from the water which has it's own circuit and breaker.  It just wasn't finished to the dock because we were re-setting where the dock was on the property after the electrician had finished.  Curious if anyone was in a similar situation regarding an in and outflowing dock.

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3 hours ago, ckhokiehi said:

gangplank is on wheels that roll up and down a concrete form which has ramps on the sides (for the wheels) and stairs down the middle.  Gangplank probably travels 15 feet vertically over the course of the year.

That makes it hard to keep everything neat and tidy for sure. At high water you are going to have slack, sounds like 15 feet worth.  No way around it. Maybe build a storage spot for it, similair to something you would coil a hose in? 

Mine is a stationary mount but a few neighbors have the roll out gangway, I'll try to take a closer look at them this.weekend.

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I'll try to grab a picture this weekend of what some of the docks near us use.  We have plenty of fluctuation and there is a coil reel to contain the slack when the lake goes up or down.  

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On 6/17/2016 at 10:19 AM, blk93jeepzj said:

I'll try to grab a picture this weekend of what some of the docks near us use.  We have plenty of fluctuation and there is a coil reel to contain the slack when the lake goes up or down.  

I was wondering if something like that was out there.  Any details would be greatly appreciated

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I spent almost the entire weekend working, but I did manage to get out for just a bit on the jetski. I checked three roll out setups near me and they are all just swim platforms without power so I'm not any more help.  I have seen setups like mentioned above in the past, where the flex cable is coiled like a waterhose and hung from a post or something. Looked like what you would see at a marina that had shore power hookups.

Edited by chris4x4gill2
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Here are some photos.  Basically a spool on a pipe with the wire attached to the spool with a female receptacle on the outside of the spool.  The male plug comes from the breaker box so that the spool can be unplugged to wind cable in or let cable out.  Let me know if you have any questions.

These first photos are of the older style on our dock, it's a wooden spool.    

IMG_3336.JPG.7a88f35b575230b6d9218f7b10aIMG_3339.JPG.dceb7971ab2da27359453dc02a5IMG_3338.JPG.e94ef4f65be768435322012cb34IMG_3337.JPG.1aa055cff26834dded53b6dae06

These are of the newer style metal spools.

IMG_3343.JPG.6f99711330087675b9ee513b80aIMG_3340.JPG.aff02792c039a09f5b0a984702aIMG_3341.JPG.8812d1d1ae1d0c80af6c1efd36e

IMG_3343.JPG

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  • 5 years later...

We have the same problem. When the water is up for the summer, we can use an extension cord to supply power to the properly wired dock, coiled out of the water, elevated and safe. However, when winter comes and the water drops, the dock moves out 15-20 feet (?). Last year, the extension cord was left plugged in, and it got caught on something under the water and when the dock rose in the spring time, the cord was cut in half. Seems like there should be some sort of spring loaded cord reel that would keep the slack out of the cord during the dynamic water changes during the winter/spring. The current answer is to keep the dock unplugged, however, I would like to keep my boat batteries trickle charged, keep the motion activated lights powered and install cameras for year long surveillance. But this requires us to keep the extension cord plugged in with the chance of it getting caught again and rupturing. thoughts anyone?

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