Trenching line from off grid power shed to house -- what to include?

[PorkChopsMmm]

So we are building a 12x24 shed that will, God willing, have all of our solar panels mounted on the roof and solar equipment installed inside prior to winter. I am in the process of planning what to include in the trenched line that will deliver AC power from the shed to our house. The distance from the new solar shed to the house is < 500ft and the run would be almost entirely straight and at level grade. the biggest trencher I can rent goes down to 36" to 40" -- freeze depth is 42". AC power for the shed will be provided by the equipment in the shed -- just to clarify -- I am trying to get AC power from the shed to my house.

My understanding is the main AC power either needs to be sheathed for direct ground burial or be in it's own conduit. Lower power stuff, like Cat5 can be in a different conduit run but shared with other lines, etc. Can you help me clarify this and identify anything I am forgetting?

Here is my list of things to include in the trench, in no particular order:
- Main AC line -- either direct burial or in it's own conduit. I only run 120 in my house, no 240 breakers or outlets, my inverter only does 120 and I am offgrid. If I am going 500ft any recommendations for wire size and direct burial or conduit?
- Cat6 ethernet (for serial communications) -- I have an Outback inverter, charge controller, etc. so as such I am using their MATE display for controlling the solar equipment. This uses Cat5 (or Cat5e or Cat6) to send a serial protocol -- not IP. As such, it can exceed the theoretical 324ft limit of Cat5 and go up to 1,000 feet. In conduit.
- Cat6 ethernet (for IP communications) -- I was thinking of putting an IP security camera out on the soffit of the power shed, facing the house. This may need an ethernet booster inline, but at least it would be in the trench. I am imagining this would go in the same conduit as the other Cat6 cable.
- 12/3 Romex -- I was also thinking of putting a 3-way switched light out on the soffit of the shed that is switched on/off from within the house and from within the shed. Since this would be another AC line, would it need it's own conduit or could it be shared with the ethernet cable? Or, does anyone know of any better way to remotely switch a light off/on from so far away?
- Water line -- I was also contemplating burying a 1/2" line for watering a garden that is nearby. I was thinking PEX since I can buy a roll in the length I need. Would poly-pipe be better?
- Rope -- Something like para-cord in the conduit with the ethernet (and if I need separate conduit for the 12/2, then para-cord in there as well) for pulling any future runs through the conduit.

Anything else you can think of? When I started thinking about all I could possibly need in the power shed this trench started to get a lot more complicated.

[alex trent]

I ran just 120v power from genset to house. 200 feet.

Used 2' PVC pipe and inside 10/3 Romex.

Found that pulling the wire through the PVC was a tough deal...not sure what as a straight run, except for a 90 on the lead in end where we could assist.  Point is use strong enough cord so you can pull it w/o breaking.

I had an exhibition trailer wired a while back and they ran elec and coax for the computers in same conduit.  Had problems with computers till I changed.  Plus the rewiring guy said dangerous to run hot wire in with computer stuff as in unlikely event of a breech, could whack someone on the computer side. sounds logical, but not verified.

[davidj]

I'd definitely skip the 12/3 for the light.  Run another cat5 cable and use low voltage to control the light (or use IP on the camera link).  You'll need a breaker and a relay (or IP switch) but you'll save a lot of money on copper and you can do other things with it too.

I'd never put hight voltage and low voltage in the same conduit.

I'd definitely run water too whilst you're at it given it's cheap to do (even if you don't connect it initially).  I'm pretty sure regular internal pex isn't approved for direct burial and it's also expensive - I think poly or PVC would be the way to go.  You probably want to oversize the pipe too given the distance - 3/4" or 1".

Be sure to find a voltage drop calculator before sizing the wire - 500ft is gonna knock you up several wire sizes.  I believe you can drop one wire size on the ground on higher current runs.  If you think you might ever increase inverter capacity I'd pull the 4th wire now too - 33% more copper but double the power if you move to 240V.

[PorkChopsMmm]

Thanks for the help guys. I will research using low voltage light switches -- I wasn't aware of that. My plan was to do what MtnDon did -- have the wire lying beside the trench and place the conduit over the wire -- instead of pulling wire through the conduit. That looked easier but maybe I am naive.

[muldoon]

So we are building a 12x24 shed that will, God willing, have all of our solar panels mounted on the roof and solar equipment installed inside prior to winter. I am in the process of planning what to include in the trenched line that will deliver AC power from the shed to our house. The distance from the new solar shed to the house is < 500ft and the run would be almost entirely straight and at level grade. the biggest trencher I can rent goes down to 36" to 40" -- freeze depth is 42". AC power for the shed will be provided by the equipment in the shed -- just to clarify -- I am trying to get AC power from the shed to my house.

My understanding is the main AC power either needs to be sheathed for direct ground burial or be in it's own conduit. Lower power stuff, like Cat5 can be in a different conduit run but shared with other lines, etc. Can you help me clarify this and identify anything I am forgetting?

Here is my list of things to include in the trench, in no particular order:
- Main AC line -- either direct burial or in it's own conduit. I only run 120 in my house, no 240 breakers or outlets, my inverter only does 120 and I am offgrid. If I am going 500ft any recommendations for wire size and direct burial or conduit?

To determine wire size, you need to determine the number of amps you intend to run over the line.  Voltage and current define the amps, and wire size is determined by amps and line loss. 

For type of cable, I like THHWN single wire.  As in you would have three indivual wires in the conduit.  Romex is not suitable for underground runs. 

- Cat6 ethernet (for serial communications) -- I have an Outback inverter, charge controller, etc. so as such I am using their MATE display for controlling the solar equipment. This uses Cat5 (or Cat5e or Cat6) to send a serial protocol -- not IP. As such, it can exceed the theoretical 324ft limit of Cat5 and go up to 1,000 feet. In conduit.

I would always say to go cat6 over cat5e as you have increased bandwidth; with 5e being 100Mhz and cat6 being 200Mhz.  You will have less crosstalk and bleedover with cat6.  In a normal house, it doesn't matter.  Over 500 feet, I think it would greatly matter. 

- Cat6 ethernet (for IP communications) -- I was thinking of putting an IP security camera out on the soffit of the power shed, facing the house. This may need an ethernet booster inline, but at least it would be in the trench. I am imagining this would go in the same conduit as the other Cat6 cable.

A few things about this.  twisted pair wiring is not designed for 200 meter runs, it is specifically about 320 feet by the standard.  That being said, I have installed it at longer distance and seen it working just fine plenty of times in different locations.  Buy the best cable you can find as all cat6 is not created equally. 
Second, cat5/5e/6 also can come in what they call direct burial cable.  Dont direct bury it, you still use a conduit, but it is somewhat shielded and will hold up longer.  Keep in mind that underground pvc conduit is considered a wet location.  It will have water in it no matter what you do, so consider getting cable that will last in it. 
Third, you should also consider the fact that any exterior ethernet is a lightning risk even underground.  They make ethernet lighting protection but I have never priced it. 
Lastly, you want the ethernet to be 6 to 8 inches away from the electrical line.  As in bury your electrical at 40" backfill a few inches, then lay in your data conduits.  Keep the EMI interference away from the data, especially as this is already a long distance run. 

- 12/3 Romex -- I was also thinking of putting a 3-way switched light out on the soffit of the shed that is switched on/off from within the house and from within the shed. Since this would be another AC line, would it need it's own conduit or could it be shared with the ethernet cable? Or, does anyone know of any better way to remotely switch a light off/on from so far away?

romex does not meet code for underground burial even in conduit.  You would need either THHWN or Service entrance or direct burial rated wire.  That being said, if you have ethernet running, perhaps an X10 enabled outlet could be used and control the light that way? 

- Water line -- I was also contemplating burying a 1/2" line for watering a garden that is nearby. I was thinking PEX since I can buy a roll in the length I need. Would poly-pipe be better?

poly would certainly be the way to go, however I do not know the rules about mixing water and electrical in same trench.  I have heard its ok in some areas and definitly not ok in others.  I personally would not want to ever hit that scenario with a trencher in the future and have not only a cut water line but a cut power line in the same trench. 

- Rope -- Something like para-cord in the conduit with the ethernet (and if I need separate conduit for the 12/2, then para-cord in there as well) for pulling any future runs through the conduit.

Good idea, but not rope or paracord.  The most common product for pullstring is called jetline.  They also make cable lube that will make pulling easier.  With a distance of 500' I think you will find it would be mandatory to use both. 

[muldoon]

- Cat6 ethernet (for IP communications) -- I was thinking of putting an IP security camera out on the soffit of the power shed, facing the house. This may need an ethernet booster inline, but at least it would be in the trench. I am imagining this would go in the same conduit as the other Cat6 cable.

Actually, you would likely be better served to use two wireless bridge devices with one at each building and use directional antennas to point at each other.  It would work better and it might even end up being cheaper.   

This should convey the idea
://www.youtube.com/watch?v=7nTgQQbF9zo

[alex trent]

Romex is not suitable for underground runs.

Even in a PVC pipe?  Is this reasonable or something that is not really bad.  Mine is in already, but getting ready to do another and want to make it right if necessary.

[muldoon]

There is a difference between will it work and is it right.  Code says NM-B cannot be used in wet locations.  Romex is NM-b cable. 

Go google this term "romex conduit underground" and you will find plenty of references for it and opinions about it.  I am not going to argue the merits of following code, everyone makes their own choices. 

Alex - I see you are from central america, and likely do not have the same codes we use.  As for how dangerous it is to put romex in pvc, it really would depend on many factors.  How corrosive is the dirt?  Whats thew pH of the ground water?  See, water will get into the wires as the sheath is not rated for water and over time corrode the copper and create a patina.  This in time will lead to the cable failing or partially failing.  Perhaps it just looses effectiveness over years, perhaps you lose neutral and create a shock hazard in the circuit, or perhaps it just works fine for 40 years.  You'll see people with all of those experiences if you look hard enough. 

[alex trent]

Alex - I see you are from central america, and likely do not have the same codes we use.

You might say that. In the countryside we have no codes and no inspection.

Have a person from the environmental agency come out and permit for that end of it because I am on the perimeter of a protected area. So you are on your own and it can get dicy because the builder mentality here is save a penny and a lot is done on hand me down knowledge which has become warped by time.

I worked around most of that by asking questions on here and doing a LOT of additional research on line and talking to folks here and in the states. amazing how little some people really know what you ask specific questions and how much bad info is out there.

My big weakness is electrical. I know the very basics. My electrician was careful and knew the basics, but i do not think much beyond that.  I believe i have "safe" connection, wire and junctions as that is fairly easy to see and I checked it all as was done. I am fused low amperage on all. I have a very low amperage fuse from batteries to inverter, so i guess i am ok there.  Have not idea at all about grounding or such things. We do have on ground from the box to a rod in the ground. Nothing on the genset which is 200 feet away and powers the house and the battery charger when running and nothing on the inverter.  My man says do not need anything above the house box ground.  Running 120v all over...no 220 as he seemed unsure about that part of it, so i just said leave it 110.

Any good basic reference on this stuff...I have looked but either too simple or too complicated.

[JRR]

A slightly different matter:  In 10 years or more, you may have difficulty remembering exactly where the trench is.  This could be a problem if you, or someone else,  needed to avoid the buried items, or perhaps if someone needed to uncover them.  So you may want to consider, as you are refilling the trench, leaving a "trail of crumbs" a foot or two beneath the surface.  "Crumbs" sometimes don't last very long .... but a row of football size stones, or bricks, or metal debris, ... or etc., etc.  This will warn anyone digging later that.... "someone has been here before"!

[PorkChopsMmm]

JRR, thank you for the advice. That reminds me, I was thinking of buying foil tape that they sell for the purpose of alerting metal detectors. That way if someone is looking for the trenched line they should be able to find it with a metal detector.

Rubble is a good idea for the times when someone just brings a shovel and starts digging.

[PorkChopsMmm]

To address the wireless bridges -- I am up for this but if I can run a hardline I would. We are off-grid so any extra power used is prohibitive. I am sure the power used by the bridges is small but that would be two additional AC devices that would need to be powered 24/7.

[Dave Sparks]

Romex is not suitable for underground runs.

Even in a PVC pipe?  Is this reasonable or something that is not really bad.  Mine is in already, but getting ready to do another and want to make it right if necessary.

If the romex is 600 V wire from a decent manufacturer and it is in decent PVC conduit that is glued or watertight you will be OK. Why you would go to the trouble of snaking romex thru conduit is beyond me. A much easier and code compliant install would have been flexible stranded individual hot, neutral or hot2, and ground in conduit.

[AdironDoc]

Now that my trench is done, I wish I'd have buried a length of bell/control wiring for any relays, etc. (remote start switch for my electric start generator), for example. Also, now that my antenna is at the peak of the roof and still only gets two channels, I'm envying my neighbor. He gets 22 channels, same antenna. He shot a line over a tree limb, 80ft up, and hoisted his unit up. I'd have run a coax in my trench to the shed at the forest edge and done the same. So, UF, Coax, CAT, and control wire.

[PorkChopsMmm]

Bringing this back from the dead as I am ready to begin trenching in the next 2 weeks. I used a large tape measure and actually shot my distances. I rounded up to 500' to be on the safe side but 250' is all I need. Guess I am not good at judging distances. I have the Cat6 and coax nailed down, think I am going to use 1" poly pipe (http://menards.com/main/plumbing/rough-plumbing/pipes-tubing-fittings/pipes/polyethylene-pipes/1-cenflo-hdpe-80-ips/p-1767878-c-8570.htm) and am now looking at how to run the power.

A few of you all said to use individual strands of wire but some of my searches have come up with many folks using 2-2-2-4 Aluminum Mobile Home Feeder cable. You all ever heard of this? Here is a link...
http://menards.com/main/electrical/rough-electrical/wire-cable/2-2-2-4-aluminum-mobile-home-feeder-per-foot/p-1469808-c-6441.htm

I am only running 120V but this would give me the added benefit of running 240V in the future, if ever needed. It looks like Menards would sell 250' of this for ~$355 plus tax -- sound about right? I am going to call local mobile home dealers and see if I can find a deal.

AdironDoc Thanks for the heads up on coax. I am going to run in to see if my cell extender (similar to a TV antenna) will work better from the far edge of our field. I wonder if the distance will create a problem. Can you give me more info on the control wiring? Would I just run some low gauge 2 wire for the relay? Thanks!

[MountainDon]

That wire would likely work. The thing to check carefully is how it will work for your particular power situation. The distance is 250 feet. The voltage is 120 VAC, for now. How many watts or amps maximum will be transmitted? Then the calculations can be done to check on the voltage drop. Ideally that should be less than 3%. Less is even better. 

[MountainDon]

By my calculator
250 feet,
aluminum 2 gauge wire,
120 volts AC,

22 amps will yield 2.93% voltage drop.

Is that more or less the maximum current draw?

If the max is higher, what would the duration of the higher load be? You can likely stand short duration loads on ocassion without wasting large amounts of power to voltage drop.

[PorkChopsMmm]

Don, I want to answer you intelligently but I'm not sure if I have all the numbers I need in front of me. If I had to guess the max wattage we use, it would be the numbers below. We don't have AC, electric heat, or any other large electric loads. All lights are LEDs, etc.

- Well Pump 600 watts when running
- Fridge 100 watts when running
- Blow dryer (wife!) 1500 watts running

That is the most I could see running at one time. So ~2200 watts... which means 22 Amps?

[MountainDon]

2200 / 120 = 18.333 amps

Sounds like the number 2 gauge wire would be sufficient. There would be a surge when the well pump starts and a small peak when the fridge starts, but that should be okay as long as the inverter can handle the power.

[rocking23nf]

Dont forget the yellow warning tape for buried electrical lines.

[PorkChopsMmm]

Thanks Don. I think most of our loads save for the water pump and fridge will be more momentary to only a minute or two.

Will do, rocking23nf.

Would you guys put the mobile home cable in conduit? We have very sandy soil with a high water table. The coax and CAT6 I am looking at are both ground burial rated. Could I just dump dirt on this larger AC cable, say a foot, and then add the coax and CAT6 also buried directly in the soil? It would save a lot of work having to enclose it all in conduit -- and separate conduit runs at that (since the high voltage lines can't go in the same run as low voltage lines, I believe).

I would use conduit to enclose the wiring as it comes out of the ground, of course.

[Pine Cone]

Another thing to remember when digging any ditch is that it may be an intentional or unintentional drainage line for groundwater or excess surface water.

My current house had some basement flooding last year associated with the water and electric lines that run from my well to my house.  Turns out that in very saturated conditions excess groundwater travels down the ditch right to the wall of the house.  It appears the house did not have a good foundation drain, so it was easier for the water to go through the wall and into the basement.  This fall we are fixing that by adding french drains that cross this ditch and hopefully move that water away from the house.

At my cabin I put some drain rock and drainage pipe in my ditch dug for electrical lines, and then extended that ditch and associated drain rock and pipe beyond where the electrical entered the cabin so the water could go to a final resting place beyond the cabin footprint.  In that situation there was ground water near the surface and the ditch for the electric would have concentrated that and funneled it into the building footprint if I hadn't continued the ditch beyond what was needed for the electric alone. 

[pmichelsen]

Any time I dig trench I will try and throw in an extra water /electrical or both. Especially when I am running conduit, I always make sure I drop in a spare conduit just in case I want to pull something new in the future.

[PorkChopsMmm]

Pine Cone -- thanks for the heads up on water. We do have a high water table so maybe I will gently slope the water away from the house with a trench that is slightly shallower at the house and gradually deeper towards the barn. It would be going out to a gardening area, which I think would help.

pmichelsen -- I need to research how much it will cost to put in an extra 250ft of conduit and see if it makes sense.

[NM_Shooter]

If not too late, consider dropping in some 5 or 7 conductor sprinkler system wire.  In case you want to implement remote sensing for security, or any control functions.