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We are building a path and stairs from our cabin to the lake which is about 200' away. Eventually I plan to build a shed to store Kayaks.

In the short term I want lighting at the lake. Other than lights and potentially running light-duty 120V equipment (powerwasher, electronics, air pump) I can't imagine what else I would need power for at the shed. On the other hand I like to plan for "unknowns".

I was planning on running a combination of buried PVC conduit and PVC conduit attached to the stairs to get to the final destination.

I'm wondering if my plan to use 1" conduit, 8# CU (4 conductors) to a a 40amp subpanel sounds reasonable.

Update 6/24/2021:

It's been over 6 months and the stairs are finally finished. I am now looking at running power to my lakeside deck. I have run 60 feet of 1" conduit underground from the load center to the top of the stairs. There are 150+ feet of stairs including MULTIPLE landings. I am now rethinking the task of running rigid conduit attached to the decking/stairs (I count 10 (ten) 45 degree angles just to get to the first main landing). Putting this underground would be very difficult given the rocky soil and steep embankment. I've priced several options and while I have time I don't feel like slogging for 3 days trying to make conduit follow this circuitous route when a marginally more expensive option might work in the long run.

Questions:

  1. Is there a problem stapling UF to the stair risers and deck supports? UF 6/3 is available and the mot expensive option but I could do this work in a day.
  2. Can URD be exposed (stapled to risers) or as the name implies, does it have to be buried? Quadraplex URD AL is only $1/foot. This is the cheapest route and fast.
  3. Is there any quick way to make the twists and turns following the stairs and landings down the hill with PVC conduit other than a copious number of 45degree angles? Mix water-tight flexible with Schedule 40 PVC? enter image description here
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  • Note that you'll also need to add a ground rod at the shed. And since it's near a lake, I highly recommend putting everything on GFCI breakers, and keep the breaker panel far back from the water -- electrical drownings are a serious danger, and GFCI will keep things safe.
    – Nate S.
    Sep 4 '20 at 16:27
  • Would you recommend a GFCI breaker in the main panel, GFCI breakers in the subpanel, or both? Yes, I was aware of the ground rod requirement which I am not looking forward to due to all the rocks.....
    – drjrt
    Sep 4 '20 at 16:34
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    I'd recommend GFCI in the main panel if you can't avoid putting the subpanel close to the shore, but if you can I'd skip it. The reason is that if the GFCI in the main panel trips, you lose power to everything until you walk back to the house in the dark and reset it. The principle you want to go by here is that no wire that's not GFCI protected should get anywhere near the water, including the subpanel's feeders.
    – Nate S.
    Sep 4 '20 at 16:38
  • @drjrt -- as to that ground rod requirement, I'd just put a concrete-encased electrode in the shed footings, myself (which can be just a thickened slab edge even) -- this works as long as you don't put plastic under the footing Sep 5 '20 at 3:28
  • This is gathering "opinion based" votes to close, most likely because of the "Should I..." in the title. Should you is something only you can decide. Edit your question to focus on the conduit, wiring and/or voltage drop and make the 120/240v decision yourself.
    – FreeMan
    Sep 8 '20 at 17:57
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The experts will come along to discuss a ton of issues, but I'll point out a few to get you started:

  • Conduit Size

The big cost with PVC conduit is not the conduit. It is the digging. Whether you do it by hand or with a machine, the digging is the hard part. At current Home Depot prices (and you may do better elsewhere), the difference between 3/4" and 1" is $ 1.20 for a 10' piece, or a grand total of $ 24 for 200'. Go "big" now. It doesn't cost much, and the cost of having to redo it is a lot more than $ 24.

  • Subpanel

Even if you only need one circuit, a subpanel makes sense. There are a bunch of reasons. One of them is GFCI protection. With a single circuit, a GFCI trip will turn off the lights as well as the tools. With a subpanel, you can easily separate the lights from the receptacles. The main breaker on the subpanel will also function as a shutoff switch for all power to the shed. You can also put in a 40A or 60A or much larger subpanel even if the feed is 30A (which would typically be enough to provide for 4 15A or 20A 120V circuits). Again, the big cost is the labor involved, so don't put in a "just big enough" subpanel, go up a size so you have expansion room - e.g., if you decided later to turn the shed into a real workshop then you would only have to replace the feed wires and the breaker in the main panel but not replace the subpanel.

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So far as shaping PVC is concerned, yes there are means other than buying lots of pre-made elbows. You can bend PVC in the field. Several methods use heat; another is done cold.

The conduit path need not strictly follow the handrail path -- if you mount the conduit to the bottom side of the walkway you'll be able to avoid several bends at the landings. Still, I'd suggest adding several junction boxes along the path as wire pulling points.

Heating with an electric heat gun or gas (propane) flame works. With the heat gun it's a little challenging to heat a section long enough to make a gentle, sweeping bend and avoid kinking the pipe. With the torch it's a little challenging to avoid scorching the pipe.

Another method heats from the outside with an oven-like tool. There are a few on the market; here's one example. (image credit: ktool.net) After the tool is warmed up a straight section of PVC is laid on those 4 rollers and the lid is closed. The PVC is rotated for even heating. After a minute or so the PVC is limp like a spaghetti noodle and can easily be formed to just the right angle.

PVC heater/bender

Another method is to put an electric heating element on the inside of the pipe. Here's one such tool: (image credit: pvcbendit.com)

internal PVC heater

Lastly, an option for bending PVC "cold": wrap the pipe with a spring to prevent collapse/kinking and bend it around your foot, knee, a post, etc. I haven't actually used this method, but I'll guess it might be hard to do for pipes 1" and larger. (image credit: rack-a-tiers.com)

spring bender

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Run the 240v and subpanel it.

I often see people make the mistake of a 120v run because initially it's cheaper (less wires) and easier (no need for a subpanel). The problem comes when you want to do something more than your wires will allow. Now you're kicking yourself for not adding one wire (cheaper) vs running new wires and adding the panel anyways.

I'd also upsize your wire. For that long a run, I'd suggest an 8 gauge THHN setup in 1" conduit, on a 20 amp 240v setup (4 wires total since you need a ground wire). Should handle the voltage drop easily.

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  • Why only a 20 amp breaker? 8 ga is good for 40 amps. I get the voltage drop issue, you wouldn't want to be pulling a full 40 amps continuously, but still, just a 20 amps brkr, seems odd. Sep 4 '20 at 14:20
  • Yes, why only a 20amp and would use use a lug panel or breakered panel?
    – drjrt
    Sep 4 '20 at 16:20
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    @drjrt, use a breakered panel, but the breaker doesn't have to match the feeder breaker -- it's fine if it's larger. It's just acting as a shutoff switch, which code requires in an outbuilding, and a main breaker is cheaper than a separate switch before a lug panel.
    – Nate S.
    Sep 4 '20 at 16:25
  • You might be able to get away with 30A, but I didn't want to push it on a light duty circuit.
    – Machavity
    Sep 4 '20 at 16:39

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