ECN Forum Forums Code Related Discussion NEC & other Code issues Walkway and boat dock

I have a walkway to a boat dock that I'm going to have to wire and install at least 3 lights on each side, then pull the switch leg to lights that are going to be under the canopy of the boat dock. I'll have 3 general use outlets on the boat dock that are NOT for boat lifts. Just for a charger and general use purposes. I know that all has to be on GFCI protected circuit, etc. Right now I'm just in the process of figuring out the best way to run my pvc along the walkway to the lights and boat dock. Problem I can't seem to figure out now is that pvc has to supported every 3ft. The pilings are approx. 8 to 10ft. apart. I can't go under the walkway, it is too close to the water. If I put 45's at every piling it's going to look really tacky and hard to pull wire. I'm going to try to post a picture if it works out alright. If not I'll try again in another post. Nope, looks like I will have to try in another post. I'll have to read up on how to get it here. I've already uploaded it to the photo section. Will try again.
Thanks

Hopefully this is 3 photos

Well, only one came through I guess, but this is the main one I'm working on right now. There will be a weather proof panel at the left of the entrance to the walkway, with GFCI breakers for each circuit going to the walkway and to the boat dock. I understand I will have to drive a ground rod, if not 2, at the panel, and will have to have a equopential? ground ring at the panel according to the inspector. Thanks again for your comments..
The lights for the walkway will have to be mounted on the side of the post, due to caps they have put on the top of the pilings. The lights are mainly for illumination so boats can see them instead of running into the walkway. I'm going to try to position them if I can so they will provide light for the walkway also. They have flat caps on the pilings, so I may if I have to, bore through the top of the caps at an angle, and put lights on the top of the pilings. I'm not that far yet.
Thanks again.

Thinking again on the top mounted fixtures. I'd have to be able to use UF cable from the top of the piling to the side where the junction box would be if it is allowed, which I wouldn't think so. It would be hard to get flex or pvc in at that angle....

Thinking about running 1/2" pvc down left side, coming up at light locations into a 7 hole wp 2 gang box, coming back out of 2 gang up to a round wp box for fixture, back out of 2 gang for fixture on opposite side under dock, (hope there's no snakes) 90 ing up to fixture on other side.(Trying to keep most of the conduit where it's not seen as you approach the walkway). Still don't know exactly how I'm going to strap it horizontally though, unless I add some kind of support between the pilings.

Might I suggest a different approach?

Try running strut horizontally, at about 'knee height,' along the walk (the idea is to make it look like it was a middle rail for the walkway). Attach the conduit to the strut using parallel clamps like these: http://www.mcmaster.com/#strut-channel-straps/=12r82g6

I'd prefer coated conduit (Ocal) for this job; in any event I'd use rigid, with threaded fittings wherever possible. PVC just seems to droop and crack. I'd also go up a size, to 3/4".

Forget "Bell" boxes. This is a place for the cast FS-type boxes.

Fixtures are available that will screw directly to conduit. Again, 3/4 rigid will give the support you need.

Coat ALL threads with anti-seize before final assembly, to keep things from rusting together. T&B's "Kopr-coat" is even UL listed for this use.

Thanks for the suggestion of unistrut. I'm trying to get away from metal pipe. Some of the emt I pulled out of the boat house was rusted into and hanging by the wires "with no ground wire in it:( I got the inspector to look at it before I started any wiring, and he said to change it to pvc ( overhead lighting). They(the one's in charge) were going to try to get power put back on it like it was. He said "No way", which is what I wanted him to say. It was easier for him to tell them than me. Didn't want to make them think I was saying that to make my job bigger. Now it is quiet a bit bigger. I've got to pull another feeder from the main building also. The feeder that was feeding it previously was only a piece of 12/2 UF. He wanted me to get a load calculation, etc.. When I told the Executive Director, He said just pull a new one. That's about 220ft. just to the entrance of the walkway underground. Thanks again.. I'll think about the Unistrut...

If you install a PVC-coated rigid conduit like Reno suggests you'll find that it doesn't sag like PVC does and the coating (inside and out) will protect it from corrosion.
Our plant has the worst environment imaginable for corrosion and the PVC-coated conduit installed 12 years ago still looks like new.
It's a bit more money up front but you'll never have to replace it.

You are in Article 555. I don't see anything that limits the height of conduits above the water, in fact the standard practice for boat lifts is to run the conduit under the water.
The limit is for the splices and devices,



PVC seems to be the choice here but we are dealing with salt water, that looks like a lake and it is much more forgiving.
I would run the PVC under the dock. That is also pretty standard here. "T" the "UP"s for the lights, just be sure there are no splices below the dock.

PVC is what I'll be using. My only problem is that I won't be able to run it under the walkway due to not being accessible because of the water level. I'm planning on running it down the left side, but I don't have anything right now to support it too except the post and I'll need some support in between the post. I'll either have to get some sort of bracket or have them nail another piece of 2x12 treated on the outside of the post for me to run my conduit on. Got to have something that won't make it look too tacky.

Why is the water level an issue if there are no splices below the dock? You could run that conduit under water if you wanted to. I said you could use "T" conduit bodies but it might be better to use 2 hole boxes and have the conduits daisy chain with no openings under the dock at all, (one in, one out) although they will accumulate water no matter where they are if they are below the boxes. I have never pulled a wire out of an underground conduit that wasn't wet it it had been there a while.
That is the standard install around here. The conduits run under the dock and come up to each box. These docks may be submerged in salt water occasionally. They were on Monday anyway. (T/S Colin)

Just my two cents....
Did you or anyone check with a building inspector regarding the walkway, with only the top & lower rails?? I don't think that would fly here.

The additional 2x12 would be a lot more inexpensive a solution, and 'maybe' be required.

The PVC coated RGS is a great solution, but keep in mind it is $$$, and requires a dedicated bender.

Unistrut makes fiberglass and stainless strut FYI.

Schedule 80 PVC would be my choice, and I would seriously 'nudge' the 2x12s perhaps on both sides for appearance. (And it may make the insurance co. happy)

Greg, I'm talking about the walkway out to the dock. I don't think the inspectors here are going to go for the pvc in the water. As far as running it under the walkway, I'd have to swim under the walkway and use a "snorkel" or something, plus run out all the snakes if any. Already had to run out one snake on the dock itself. After the inspector seeing what shape it was in before, I'm sure it's going to have to be out of the water. And yes, I did have an inspector out there before I did anything. He's the one that required me to rewire it. I tried to meet with one of the plan review personnel this morning, but he referred me to the same inspector over the phone, and he pretty well didn't give me any other information than I knew. I guess this is just a "design issue" and they didn't want to get into it. I guess he figures I can read the Code just like them, which I can, but there's sometimes "gray areas" in there as we all know. Plus where this job is, is back in the "boonies" so to speak. Takes a while to get there. No supply houses real handy, so I have to try to make each trip effective as possible.
I've already pretty well got the lights under the dock roof wired, just a few more things. I'm just getting ready to run the feed and switch legs. Still got some bonding to do on the ladders, ramp, etc..
John I will check on the fiberglass or stainless Unistrut.
Thanks for all your comments. Just wanting to do it right and safe as possible and not make it look too tacky at the same time. This establishment if for "The Lions Club" which
does things for the blind and visually impaired. They have certain times they come in big groups and have staff members help them enjoy boat rides and swimming. Actually they are there now, so I'm limited when I can work. It has to be late in the afternoons or on Saturdays. After all the news about the fatalities of electric shock around boat docks for swimmers, I'm trying to be extra safe as I can. I know most of those fatalities are associated with boat lifts etc., but they don't want me to cut corners.
Thanks again

I believe strut is also available in aluminum .... check McMaster-Carr for a full selection.

OK, fine, use PVC .... but support it as continuously as you can. Like, lengthwise along strut as pictured with the clamps I linked to. You could even do most of that using wood and 2-hole straps.

The key is complete support under the PVC for the entire length. Otherwise, PVC will sag, look poor, and it becomes brittle with time. There's also the risk of the pipe being used as a tie-off point foothold, etc. These are additional reasons for 'going big.'

As for the fear of electrical shocks in the water .... just a silly idea here ... How about running a #4 copper wire down each pier into the water, and bonding them to your circuit ground? That would surely reduce the chance of any "voltage gradients."

Contrary to common practice in our trade, I'd also clean & prime the PVC before applying glue.

BTW, stainless conduit and fittings exist.

If you do not want to get in the water, no problem but I do not see an issue code wise about running it under the walk way. It looks to be above the water anyway in your picture but there is no code reason why it can't be underwater if it had to be. It is still a wet location.
I do agree with Reno, PVC will never look great if you have to look at it but those PVC 2 hole straps do not hold up. I would use something else.

Call the AHJ and ask what he wants to see. This can't be the only dock they have wired around there.

I agree that the PVC-coated rigid costs a bit more, but here's an 'outside the box' idea since you said that it's for such a worthy cause.

Since PVC-coated conduit is used in water, wastewater and chemical installations, ask around and see if there are any Contractors who have leftovers from a previous job that they're stuck with.
They might be persuaded to donate a few lengths...perhaps for a tax writeoff.
The local water/wastewater plants may even have something usable in their scrap pile from a renovation that you could have for the asking.

Based on the pictures you could do the whole job with several straight lengths and may only have to buy a few fittings and boxes.

Greg, how do you get past the supports every 3 ft. when running under water or even under the walkway I pictured, where I can't get too?
And Reno, your comment about it being a silly idea of electric shocks in the water. I've been reading of a lot of fatalities of people getting eletocuted while swimming. Maybe I'm misunderstanding what you meant. Right now I can't remember the name of what it is technically called.

Next time I get a chance I'll ask our inspectors here about running the pvc under water.
Thanks again for the input.

You should be able to run it inside the horizontal stringers the deck boards screw into but I was looking at your picture again.
You could run the pipe along those tails that stick out at each piling. Maybe have them nail a 2x along the ends for support. Then you won';t have to get in the water at all.

Keep in mind that if it can be reached from the water a swimmer will use it as a handhold sooner or later.

The side that is designated for swimmers is roped off and these swimmers are monitored, because most of them are visually impaired, but I know what you mean. If it's possible it'll be done. If I add the 2x12 it should protect the conduit from being in any sort of strain from hand holds in the future. They will be grabbing hold of the 2x12 .
If it works out, I'll probably just running the 2x12 on the left side of the walkway, which is on the opposite side that is designated for swimming. I'm suppose to go out this afternoon to look it over again, and tomorrow to do work on the dock. I'm going to try to get on the water and see if there is an option before I make my final decision. And no, I'm not for getting in the water. At my age it wouldn't be fun, plus I'm not the Olympic swimmer by no means
But thanks for the inputs. I will certainly keep all of these in mind.

I called my idea 'silly' as a way to downplay it. Call it modesty. There's no harm in doing so, but there is no code requirement - yet! Were this a pool, then there would be a requirement for an 'equipotential grid.'

I'm not aware of any conduit that requires support every three feet. Though, as my earlier description of using strut made clear, I encourage supporting conduit in excess of 'code minimums' where I believe the conduit will be subject to additional loading ... as when a kid climbs on it!

"Stray voltage" and "transient voltage" are terms sometimes used to describe folks getting shocks while swimming. These instances have almost always involved three things:
1) CLEAN fresh water;
2) A pool shell that was effectively insulated from the ground around the pool; and,
3) A municipality-owned electrical utility that was using the earth as a return path for it's various transformers.

The NEC adopted a few things in an attempt to address these issues. The first was to make an equipotential plane around the pool. The next was to require you to "bond" the water, by bonding a piece of metal that was in contact with the pool water.

This installation seems to be a typical Article 555 pier. There are at least 50 of them within a mile of my house and most have power. I can get pictures of the "good, bad and ugly" if you guys want to see some.
You can't confuse this with the Article 682 "natural and artificially made bodies of water" because that refers to equipment in the water, not above it on a pier.
I agree there are inconsistent rules between the two but "welcome to the NEC"

Reno:

Check 352.30

"I'm not aware of any conduit that requires support every three feet."

I understand you do not adhere to the 'minimums' within NEC, but just an FYI.

With that long a straight run, you also need to be thinking about expansion joints.

OK, expansion joints now enter the debate. I thought of bring it in a few posts back, but decided to wait.

NC lake area, venture about 85-105 degree swing??

Add in the proper straps that allow movement of the PVC, as opposed to the 2-hole that fit and screwed really tight.

352.30? By golly, it does say every 3-ft. for the smaller PVC. Thank you!

I don't think I've ever seen it done, though ... hence my comments about it drooping, etc.

I would say, it would be more like 105 down to the teens. I would design for 100 degrees. Even here in the sub tropics we need to deal with 85 degrees or so (in the shade)and it never freezes here. Direct sunlight will add at least 20 more degrees, particularly over a solid surface like a roof, concrete slab, masonry wall etc.
PVC may be the worst for expansion rate and it will pull apart if it is too tight. That "droop" may be a good thing if it is hot. I went with EMT in my screen cage just for that reason but it is not really an option on a boat dock here because it will rust out right away. YMMV on a freshwater lake but it is still just a matter of time.

Reno:
Don't feel too bad, not a lot of guys ever saw that Article.

Heck, I still 'preach' expansion joints to a few!

We talked about this in this thread and I said I would give you the good, the bad and the ugly.

This is a good one
Note the pipe to the outboard motor goes underwater.



This is the bad
Those Carlon 2 holers just disintegrated.



The ugly. Note the galvanized octagon box is totally gone and the keyless is hanging by the wires

One of the 'things' my work Twp does not have is waterfront except the Twp ramp into the river, and a "Marina" I have not been to in 15 years.

Home, is another story. What "New" I have seen is PVC, PVC boxes, SS boxes. Yes, there are ugly ones also, I'll see if I can get some pics in the next week or so.

The river by my house is lined with docks and lifts. There are also canals for additional dock space so we have lots of work going on. I doubt 20% of it is permitted and inspected.

Got the 2x10s up. I'll try to post a picture when I get time. Just,wondering how many expansion couplings I would need on a 100ft. Run of 3/4" pvc conduit?

If you design for 100f degree swing and 100 feet out, it is 4.06" according to table 352.44
Carlon has a pretty good guide
https://www.platt.com/CutSheets/Multiple/ConduitExpansionFittings-CutSheet.pdf

One thing to remember is if you elbow up and down to each light along the way, you are breaking up that expansion and if you don't strap the vertical too close to the elbow, you get quite a bit of "wiggle room". I don't really see than many expansion fittings if they can do a flexible enough design.

I will have 1 (3/4) run the length of the walkway feeding the boat dock. I will run the lights on the walkway in 1/2". I figure the 3/4" is the one mainly that,will need the expansion fitting.

Both runs them will expand and contract with the temperature changes...and to the same degree.
I'd put 2 expansion joints in each run; it's cheaper than maxing out the one fitting on a really hot day and having to rip everything out and start over.

As long as the run has regular (interval) elbows up and down for the lights, that will usually handle the expansion. Just be careful not to strap too close to the elbow on the verticals so they have some wiggle room. You can strap the horizontal a few inches from the elbow to secure it as long as the pipe can move. On the long run, I would use several expansion couplers so they spread out the work. You don't want the pipe to bind, halfway down and pull apart or rip out the straps. Those plastic straps are junk anyway. I would go for stainless 2 holers if you can get them. I know the dock guys use them here so they are available. It may be a plumbing store thing.

Can't seem to be able to find the exact type flex needed between the pier and the ramp needed for flexibility. I know it has to be watertight, but can it be carflex. Looks like if you use flexible metal that the metal ground would eventually break into with all the up down motion of the water. Also, article 555(I think that's right) says it is not for private or non commercial use. Please refresh6 me on the article that does pertain to it. It's been a rough job bouncing on the the waves and my brain is sorta bouncing too. Thanks

555.13(A)(2) says you can use SO cord (assuming the right grips on each end) If you needed additional protection I guess you could sleeve that in Carflex since it is a chapter 3 wiring method as stated in 555.13(A)(1), pursuant to protection in 555.13(B)(a)(5). If there are sections above the deck you need RNC per 555.13(B)(5)

Just make sure that you get the UV and water resistant cord or you'll be replacing it next season.

You are right. I used the generic "SO" but that seems to end up being SOOW around here.

When bonding an aluminum boat ramp, it seems like with the constant moving of the water, that #6 solid copper would eventually break into, but that's what I'm coming up with as far as requirements go. Any ideas, or should I just do it and not worry.
Thanks

That is worth a call to the AHJ. I would prefer a stranded wire in that application for the reasons you mention and in salt water I might "suggest" for it to be "potted" (gel shrink wrap or something) into a terminal but that would just be a suggestion. I don't think I would find the language to make it so. That is more from wiring boats than docks.
The bottom line for everyone should be safety.
If something is required to be bonded, it should stay bonded.

The braided ground/bond straps have been an acceptable alternative to the flex issue by most (not all) inspectors.

I suppose corrosion may not be a big deal in a northern lake but a braided strap would not last a year in tropical salt water

Greg:
I know your point and agree. However, a comment that I have heard a few times is something like "the inspection is for the time (day) you are there, and you cannot look into the future, or the next day"

You are starting to sound like the guys who have one patio door pool alarm that they take from job to job

Or....the local EC that had his guy swap out the bubble covers for old style flaps, after the final inspection. He 'moved' them to the next job for that final.

OOPS, yes, I was still there when the 'removal' was happening one day!!

I was fortunate that the <state> projects I was inspecting were going to belong to the guy forever so they wanted an installation that would last. It was easy to work together for the best solution on questions. I understand people going for the lowest bidder can't be as choosy

Greg:
This sitem may last for a bit...

http://www.emersonindustrial.com/en...ound_fitting/flex-braids/Flex-Braids.pdf