Boat Dock Power

[Dwleo]

Hi Guys,
This summer I am going to run 20A power down to but not onto the dock. It will traverse 150 feet from the main box in the cabin to a sub-panel on an extended deck (affectionately called the wine deck) that is just before the dock ramp. As this is on very rocky ground, I was going to use armored cable attached beneath the stairs leading down to the deck. GFCI outlets on the deck to run the covered bar fridge, tools and whatever. I might run power down the ramp at a later date but probably not as I won't have a lift.
Now questions I have:
1. gauge and # of conductors required
2. Ground rod??? This is rock and would be next to impossible.

Thoughts?

 

[Kevin Essiambre]

I'm assuming when you say armoured cable you mean Teck cable right? If you go 6awg or larger I would use ACWU which is aluminium conductors instead of copper (copper is expensive).

I've attached section 78 of the CEC. I do not know what local code ammendment there are.

You will need class A GFCI protection on the receptacle(s) you install on the dock.

It must be mounted above the waterline at high tide. If the dock is floating I believe you're okay if its mounted on the dock so it will go up and down.

Because its water and power, please remember to get a permit.

I would run #6 3 conductor aluminium cable but I cannot say if the voltage drop would be within CEC requirements and I don't feel like doing the calculation for what amperage that could support. #6 copper at 150' would be 2.21% voltage drop.

There are calculators online for voltage drop too.

Sent from my new phone. Autocorrect may have changed stuff.

 

[tarmy]

Be careful of wiring things on docks (on water)...stray power or improperly grounded equipment can be very dangerous...

I terminated mine at the shore...and had an electrician I trust check it all. The dock winch has a dedicated circuit and disconnect at the top of the gangplank in case there is an issue.

Electrical strikes (lightning) are an issue to think about as well.

 

[walta]

I say pay the man to do this one.

Could you look into your daughters eyes and explain how sorry you are her child is dead because you made a mistake trying to save a few hundred dollars?

I would insist the GFI be in the breaker box of the house as it is the only way to insure safety at the dock, yes it will be a pain in the tail when it trips.

https://www.stltoday.com/news/local...cle_3f5ebfa7-949c-53fe-8ec5-f4d9f258a66e.html

Walta

 

[mike93lx]

In the US, a subpanel outside of the main structure requires a pair of ground rods (one is ok of you can prove resistance meets a threshold, but everyone installs 2). I would be surprised if CA was different.

Do you really only need 20A? 120V or 240V? If 20A 120V, I would probably skip on the subpanel and run a single circuit. Way simpler and no ground rod (in the US)

 

[Kevin Essiambre]

In the US, a subpanel outside of the main structure requires a pair of ground rods (one is ok of you can prove resistance meets a threshold, but everyone installs 2). I would be surprised if CA was different.

Do you really only need 20A? 120V or 240V? If 20A 120V, I would probably skip on the subpanel and run a single circuit. Way simpler and no ground rod (in the US)

I've never had to install additional ground rods or a ground plate up here for a sub-panel.

We have a lot of different codes up here.

Sent from my new phone. Autocorrect may have changed stuff.

 

[Dwleo]

Thank you all for that. To answer a few of the questions:

Kevin: It would be copper not aluminium; closest point to water is 10 feet at high tide;
Mike93lx: 20A 120V

 

[rlitman]

I say pay the man to do this one.

Could you look into your daughters eyes and explain how sorry you are her child is dead because you made a mistake trying to save a few hundred dollars?

I would insist the GFI be in the breaker box of the house as it is the only way to insure safety at the dock, yes it will be a pain in the tail when it trips.

https://www.stltoday.com/news/local...cle_3f5ebfa7-949c-53fe-8ec5-f4d9f258a66e.html

Walta

I think you're going overboard in saying to pay someone else to do this. That's not necessarily a better guarantee of doing it right.

As for the GFCI, I agree that the feeding breaker should absolutely be a GFCI. For my own purposes, I'd also have GFCI receptacles. Yes, trips may be a nuisance, but GFCI protection is serious life-safety.

Thank you all for that. To answer a few of the questions:

Kevin: It would be copper not aluminium; closest point to water is 10 feet at high tide;
Mike93lx: 20A 120V

Well, being that you said tide, I'm guessing this is around salt water?

The good news is that from an electrocution hazard perspective, salt water docks are counter-intuitively far safer than fresh water ones.

The bad news is corrosion may be a real headache.

At the dock end, I'd coat all my terminals in dielectric grease before making them up, and yeah, forget about aluminum.

 

[ripperd]

I would also make sure to use a GFI tester once everything is complete to be sure it is working properly.

 

[kd3pc]

proximity to other sources of current, stray or otherwise seems to be the culprit in many events. As rlitman says, salt water is actually good news on this point.

I would do a good 360 sweep to see what boats/docks/equipment and so on are within a 200-300 foot circle of your proposed.

Corrosion will be an issue in short order and rlitman hits it again with the grease and AL is not an option for these types of install. You will be chasing gremlins with AL.

 

[rlitman]

I would also make sure to use a GFI tester once everything is complete to be sure it is working properly.

Assuming the wiring is done correctly (and with a breaker it has to be; with a GFI outlet it is possible to get the line/load wrong, though some will have a status light to indicate this), a tester provides nothing that the internal self-test button can't do.

 

[kd3pc]

a current leakage detector would be the best test unit, rather than depending on GFCI.

check them out, they are much more usable today than years back.

 

[Norcal]

a current leakage detector would be the best test unit, rather than depending on GFCI.

check them out, they are much more usable today than years back.

The ONLY recognized test for GFCI’s is the test button of the device itself.

 

[mike93lx]

I've never had to install additional ground rods or a ground plate up here for a sub-panel.

We have a lot of different codes up here.

Sent from my new phone. Autocorrect may have changed stuff.

That's what I used caveats.

Code or not, a ground rod wouldnt hurt

 

[kd3pc]

The ONLY recognized test for GFCI’s is the test button of the device itself.

not meant to say there is a test for the GFCI, you are absolutely correct....

FYI

Where cases of current leakage has caused injury, the leakage test gear is more reliable in reporting current at a level to cause injury. The GFCI did not/had not tripped, even though stray leakage was the proximate cause.

More information at

https://www.boatingmag.com/installing-an-equipment-leakage-circuit-interrupter/


Blue Seas has a test unit for these, the US has been quite lax in endorsing ELCI, but Europe hasn't and in the years between this article and today a lot of lives have been saved.

 

[Norcal]

A normal GFCI trips at 6ma, that device trips at 30ma, just like a RCD used in Europe.

 

[ripperd]

Assuming the wiring is done correctly (and with a breaker it has to be; with a GFI outlet it is possible to get the line/load wrong, though some will have a status light to indicate this), a tester provides nothing that the internal self-test button can't do.

Well yes, but the goal here is to eliminate ALL assumptions, and actually verify it will work properly. What if the electrician was having a case of the Mondays and hooked it up to the wrong breaker?

 

[ard]

why not run conduit? Sounds like you are going to attach this to or under existing decking/steps? PVC- as long as it isnt subject to physical damage- should be easy to install. Could use flex for transitions, etc.

You need #6 copper in conduit for 20Amps (2.21% voltage drop)

#8 Cu will work for 15 amps (2.59%)

 

[dcg9381]

I haven't done a dock before, but I know of at least one death here due to improper grounding (and likely feeding). I'd pay for a GFCI feed from source also (just like a hot tub) if you ever intend on delivering power to the water one day in the future.

It's rocky as @#$#@$ here too, I use PVC and need a rock saw to trench. Rock saws actually take most of the ugly off the rock in the trench, but your geology may be different. Combo of flex and conduit as necessary for the cut, cover it up, and I don't worry about it in my lifetime...