Dock/Boatlift/Shorepower Wiring

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  #1  
Old 10-18-06, 06:27 PM
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Dock/Boatlift/Shorepower Wiring

Basics: My house service panel is 200 amps. Dock is 42' long and I have a 12.5k lb overhead galvanized I-beam lift with two 1.0 hp GE motors from United Boat Lift, Inc.

I have run 50amp 6/3wg UF line approx. 100' to a subpanel at the bulkhead end of my dock. UF wire is not connected to the panel just yet.

The dock subpanel is a Homeline Square-D 100amp, 8 breaker/16 circuit outdoor panel. It has of course two hot lugs and a neutral lug. I have also purchased the ground bar if necessary, though I'm not sure at this point?

My lift up/down switches "currently" are the twin "Furnas" style switches, but will shortly afterwards install a Gem Remote control switch panel. I want to connect my lift up in the 240V mode vice the 120V. It will do both of course, but I've been told it's easier on the motors when utilizing 240.

I have also yet to connect it to my house panel which is a tad clobbered right now and I was thinking of piggy-backing it to another breaker pending a total replacement with a bigger service panel, though I'm not sure which of my current breakers is best to do this "temporarily". It has been suggested to me to install a subpanel directly below the main to supplement the additional breakers/feed needed outside. Most likely I will do this.

Okay working back towards the house beginning with the lift switch/motors.....

I have temp-rigged (using a makeshift 12/3wg extension cord, hard wired to lift, plug on other end) and have wired the switch/motors to the various setups recommended for each with the caveat told me they're not necessarily always correct??? So of course I can't get it right for running up AND down. I've got it to run one way or the other, but not both. Again I'm looking to set them up in the 240 volt configuration. Anyone hip on these motors and switch setups?

Okay then run a 3 wire (two hots/ground) setup back to the dock panel.

At the panel with GFCI shutoff breaker nstalled and others, how should that be grounded in terms of the feed from the house (i.e. ground bar with copper wire run to pipe driven in yard?) and what about the ground coming from the lift wire?

Any insight would be greatly appreciated.

Rick
Va. Beach, Va
 

Last edited by Boater59; 10-19-06 at 04:57 PM.
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  #2  
Old 10-19-06, 04:59 PM
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I cleaned this post up a little bit and made it more specific as I realized I was jamming too many questions into one post.

I have a separate post for the house main service & subpanel issues called "Add Subpanel to exisitng Service Panel?"
 
  #3  
Old 10-20-06, 10:58 AM
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> I have run 50amp 6/3wg UF line approx.

That's actually good for up to 60A.

> I have also purchased the ground bar if necessary

It's required.

> it's easier on the motors when utilizing 240.

It is best to use the highest voltage a motor can take; 240 in your case.

> I have also yet to connect it to my house panel which is a
> tad clobbered right now and I was thinking of piggy-backing
> it to another breaker pending a total replacement

Technically, piggy-backing is not a legal option. Can your panel take a quad/tandem breaker? This is essentially two double-pole breakers that fit into the space of a single double-pole breaker.

> how should that be grounded in terms of the feed from
> the house

At the dock panel, the black and red wires from the UF cable go to the panel hot lugs, the white from the UF cable goes to the neutral lug, and the bare wire from the UF goes to the add-on ground bar. The ground bar and the neutral bar should be isolated, which requires you to remove (or not install) the green included bonding screw/strap from the neutral bus.

> and what about the ground coming from the lift wire?

It goes to the add-on ground bar. Nothing is connected to the neutral bar from the 240V motor circuit.
 
  #4  
Old 10-20-06, 01:35 PM
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Excellent. Thanks. So the screw/bond strap would be found or placed on the "neutral" bar not the add-on ground bar "if" it were used which in my case is NOT used and will be removed if installed. Sounds easy enough to me. So no pipe in ground with copper wire running from ground bar to pipe?

Nutha question:
I'll be running a 240V line from the dock panel to the switch box at the lift controls which are two manual up/off/down switches made by FURNAS fed by one line. This line is a of course 240v with 2 hots (black/white) and one copper ground. I believe the ground will be connected to the equipment service ground from the switches & motors. Does this copper ground also connect to the separate ground bus inside the dock panel?
 
  #5  
Old 10-20-06, 04:01 PM
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> screw/bond strap...removed if installed

Yep. The instructions that come with the panel usually include a diagram that points out what pieces to remove.

> So no pipe in ground with copper wire running from ground
> bar to pipe?

A ground rod would be required if this subpanel fed an outbuilding, but I don't think it is mandatory for an outdoor panel mounted on a post. It also would not be wrong to add a ground rod, in my opinion. I'm not certain so someone else may want to weigh in with a code reference.

> 240v with 2 hots (black/white) and one copper ground.

When you install this (or any 240V) circuit you should mark the last few inches of the white wire with a red sharpie marker or some red electrical tape to re-identify it as a hot wire. This is required by code to prevent accidents down the road when someone mistakes a hot wire for a neutral.

> Does this copper ground also connect to the separate
> ground bus inside the dock panel?

Yes. At the subpanel, the bare grounds land on the add-on ground bar.
 
  #6  
Old 10-20-06, 05:38 PM
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>A ground rod would be required if this subpanel fed an outbuilding, but I don't think it is
>mandatory for an outdoor panel mounted on a post. It also would not be wrong to add
>a ground rod, in my opinion. I'm not certain so someone else may want to weigh in
>with a code reference.

[Edit: So as not to confuse anyone... this post is wrong. I recanted later in this thread.]

Nah, it still wouldn't be required- permitted, but not required- a grounding electrode is only required at the service entrance from the poco. All outbuildings fed from that grounded service can use the main building's ground, and don't need to derive their own. EG, if you run power to a shed or detached garage from your house, you don't need another ground rod, just a bare copper wire from the house. There's nothing probibiting adding more ground rods if he wanted to. In fact, if he'd run metal conduit, that metal conduit would be considered a grounding electrode if properly bonded to the ground bar.
 

Last edited by grover; 10-24-06 at 02:27 PM.
  #7  
Old 10-23-06, 11:05 AM
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I have wired four residential boat docks this year and have always driven grounds( NEC 250.32) at the panel for the seperate structure. I place a panel at the shore next to the dock to satisfy NEC 225.32. Most of the inspectors have wanted ground rods.
 
  #8  
Old 10-23-06, 02:19 PM
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[Edit: So as not to confuse anyone... this post is wrong. I recanted later in this thread.]

Mike, 250.32(A) clearly states the grounding electrode is not required in this case, and probably not in any of the docks you've worked on recently. There's nothing wrong with running an extra rod (only makes it safer!) but it's completely optional:

250.32(A) Exception: A grounding electrode shall not be required where only a single branch circuit supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the non-current-carrying parts of equipment. For the porpose of this section, a multiwire branch circuit shall be considered as a single branch circuit.

Is there anything in Articles 680 or 682 that would overrule this? I only see references back to Article 250, but I'm not all that familar with these articles. (Boater: you probably should be, though there are a lot of special rules you need to be aware of!)
 

Last edited by grover; 10-24-06 at 02:28 PM.
  #9  
Old 10-23-06, 03:10 PM
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Grover, a subpanel is NOT a single branch circuit.
 
  #10  
Old 10-23-06, 03:30 PM
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ooooookay.

So am I to take away that an additional grounding rod is necessary? or not? If not, I guess what I'm understanding is IF I went a head and installed one worst case is it would simply be considered overkill. Correct?

For discussion sake, which is best, copper pipe driven in, or good ole fashioned Rebar?

MikeVa....Can I do this right next to the bulkhead? It would end up in wet soil at about 5 feet down. Would that be good enough?

The copper wire simply attaches to the add-on ground bus bar then to the pipe/rod where it is attached by one of those clamps. Is just wrapping the copper wire around it tight good enough?
 
  #11  
Old 10-23-06, 04:21 PM
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> would simply be considered overkill. Correct?

Correct.

> which is best, copper pipe driven in

In the electrical section of the store, you will find ground rods. They are copper plated 1/2" or 5/8" rod, 8 feet long.

> to the pipe/rod where it is attached by one of those clamps.

An acorn clamp; the wire goes in the notch and the screw goes against the rod. The other end of the wire attaches to one of the lugs on the ground bus.

> Is just wrapping the copper wire around it tight good enough?

No.
 
  #12  
Old 10-23-06, 05:33 PM
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racraft, Article 210.2 specifically lists switchboards and panelboards as types of branch circuits. (Edit: still poring over the code on this one, as I'm seriously doubting myself)

Boater59, NEC gives plenty of options on what you can use as a ground rod, but they've all got to be 8' long. Easiest just to buy a specially made ground rod- will save you back driving it in! The grounding electrode conductor should be #6 Cu in your case, and it is required to be continuous between the ground rod and your panel, no splices or other connections. Needs to be solidly bonded to the rod with a listed device, and needs to be protected by SCH 80 or other conduit until it gets to the rod.
 

Last edited by grover; 10-23-06 at 06:27 PM.
  #13  
Old 10-23-06, 06:08 PM
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How can the connection remain exposed when the rod is required to be in contact with the ground for 8 feet?

If the connection remains exposed less than 8 foot of the rod will be in the ground.

PS ground rods are required at more than just the POCO connection.
 
  #14  
Old 10-23-06, 06:27 PM
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Ah, you're right, 250.68(A) requires the connection be accessible, but doesn't apply if it's buried. I'll edit my previous post to not confuse.
 
  #15  
Old 10-24-06, 05:03 AM
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I generally place my panels on a 4x6 post about 3' down. It all depends on far the tide comes in as to how close you can get to the shore. You wouldn't want the tide to come in and lift your panel out. As far as a ground rod it depends if you consider the boat dock a seperate structure. IMO that it is and I drive a rod in which the connection does not have to be accessible(the connector has to be labeled for direct burial). Though the AHJ may want to see it so I usually do not cover it untill after passing inspection. The rod must go 8' down. This depth is fairly easy that close to the water. I have never protected the grounding electrode conductor in anything. The GEC is buried from the rod to the post and stapled to the post as comes up into the panel. The #6 GEC cannot be subject to physical damage

As far saying 250.32(A) does not apply, I disagree.

2002 NEC

250.32 Two or More Buildings or Structures Supplied
from a Common Service.
(A) Grounding Electrode. Where two or more buildings
or structures are supplied from a common ac service by a
feeder(s) or branch circuit(s), the grounding electrode(s)
required in Part III of this article at each building or structure
shall be connected in the manner specified in
250.32(B) or (C). Where there are no existing grounding
electrodes, the grounding electrode(s) required in Part III of
this article shall be installed.
Exception: A grounding electrode at separate buildings or
structures shall not be required where only one branch
circuit supplies the building or structure and the branch
circuit includes an equipment grounding conductor for
grounding the conductive non–current-carrying parts of all
equipment.

In this case I believe Boater59 is running a feeder to a panel at a seperate structure and then running branch circuits. Of course the local AHJ can disagree.
 
  #16  
Old 10-24-06, 10:57 AM
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I guess the interpretation lies in what classifies "structure" in the NEC. Otherwise one would think of the dock as just a wooden platform much like a wooden walkway.

I am in fact running a feeder out to a 100A 8 slot/16 circuit outdoor subpanel to be mounted on a 4x6 bolted to a 2x10 stringer along the side at the base of the dock maybe 4 feet form the bulkhead edge in which it will be split out via breakers into at least three separate circuits (boatlift, shorepower-tower, 120v line for outlet and pole light).

Sooooo, what I'm gathering is I need to drive a dedicated grounding rod into the ground 8' which in my case will be next to the bulkhead since I don't want copper wire all over the place. From there I run the CU wire alongside the dock framing and up into the subpanel and connected to the "unbonded" add-on ground bus bar. Now this ground rod will hammered down just to where I can access the connector. Outside of cosmetics, does the CU wire have be in conduit like the flexible PVC type?

Also I've been reading more "wiring books" and in one it was discussed about using Slimline breakers to help make room for say the subpanel feed breaker without adding a sub inside the house. Any thoughts on this approach, or any negatives/restrictions in doing this?

My current main house panel is a Westinghouse CAT# B24-40 BFN,BSN.
 
  #17  
Old 10-24-06, 01:19 PM
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> Outside of cosmetics, does the CU wire have be in
> conduit like the flexible PVC type?

Only if the wire could be subjected to physical damage such as a lawn mower or vehicle. If you're running alongside an unexposed framing member of the dock, no additional protection is required.

> Slimline breakers...Any thoughts?

I'm not familiar with that panel, but if it permits slimline (sometimes called tandem) breakers, then go for it. That's what they're designed for. Usually, the label on the panel will say if tandems are allowed; sometimes you have to infer they're allowed from the space/circuit limit. For example, your new panel is an 8/16. That means you can have 16 circuits in 8 slots which implies you are allowed to use tandem breakers to get 2 circuits per slot. See if there are similar ratings marked on your main panel.

I'll hazard a guess that the B24-40 is a 24 space panel with 40 circuits which implies you can use some type of mini breaker. Check with an electrical supply house and they will be able to match a breaker to the panel model.
 
  #18  
Old 10-24-06, 02:25 PM
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FYI, I've changed my mind on the grounding rod. Namely, table 210.2 that lists switchboard and panelboards as a type of branch circuit is actually referring only to control circuitry within the switchboard. As everyone else has been trying to tell me, the feeder is a feeder, not a branch circuit. Ergo, the exception that I was certain applies doesn't. So, now I'm going to have to sink a freaking ground rod for my shed, too!

Or maybe not... That said, there are still two weasel factors. One is the definition of "structure". This is debateable. However, the debate would quickly end with the AHJ declaring the dock/shed/etc to be a structure, and that's the end of that.

The other is that even through 250.32 requires a grounding electrode, 250.50 doesn't say where it must be. And 250.64(C)(3) allows the use of panel bus bars as splices- therefore, you could technically run your grounding electrode conductor back through your main panel to the house ground rod and be perfectly legal.
 
  #19  
Old 10-25-06, 02:47 PM
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So in taking the "what the heck" approach of going ahead and running a grounding rod to the debated structure subpanel, the inspector at "worst" would say hey nice job, but the rod was overkill....Sounds easy enough to me.

Thanks everyone for your guidance thus far. Should I run into any more sketchy situations I'll resurrect this post. I might be doing a "similar" deal with my small exterior shed as well which is currently powerless, so this has helped alot.

Rick E.
Bay Island
Va. Beach, VA
 
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