AC -> DC -> AC pond wiring - good idea or stupid?

Discussion in 'Pond Construction & Equipment' started by johnkim, Jun 1, 2018.

  1. johnkim

    johnkim

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    Hi,

    I want to build a fountain in my front yard. The only problem is that I don't have any easy way running any power to center part of my yard because of my driveway. However, there is an existing DC wire for my landscape lights.

    Technically, I can have someone run an AC wire under the driveway but that's gonna be costly... Alternatively, I can try to power my fountain using low voltage DC as I already have DC wiring to the location. Unfortunately, most DC pumps are underpowered.

    The final idea is to convert my DC line back to AC near the pond using an inverter. This seems to be the safer and cheaper option than running an AC line under my driveway.

    Is this a good idea? Any safety issue?
     
    johnkim, Jun 1, 2018
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  2. johnkim

    Sparky

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    Numerous issues. Power loss factors, voltage loss on LV side. What size wire is the LV? What’s the transformer rated at. Would the LV circuit also be feeding lights. Voltage loss on any DC circuit will be large at anything over 15 feet. I could ramble off some math for you if you like or you can trust me (electrician). I see where your going with this but not the right approach. Damage to supply transformer, the inverter, supply conductors and the pump are highly likely if you got it to fire up at all. For info purposes if you had the wattage rating on the pump, the power rating in VA of the transformer I could come up with some startling numbers for you. Alternatives? Solar power.....eh cost factor. Cheaper to dig it in. No way to scratch in some UF cable?
     
    Sparky, Jun 1, 2018
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  3. johnkim

    poconojoe

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    Sparky is correct. How wide is your driveway? There's no way you can approach it from another side of your house? How is your driveway laid out in relation to your house/garage? Have you looked into the cost of hiring someone to at least install a conduit just under the driveway part? This way you can pull in whatever wire you need. There are machines that do this with ease. It might not cost that much.
     
    poconojoe, Jun 1, 2018
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  4. johnkim

    johnkim

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    Hi Sparky & poconojoe,

    Thanks for the tips. I've attached a photo of my property. The red area is the pond. The blue area is the 110V GFCI power source and also the source of the LV line. I think the distance is about 25 feet.

    The existing LV line is pretty thin gauge but I'm thinking fishing another low gauge LV line(12 or lower) and a dedicated transformer for the garden pond:

    1. One 120w(or 200w) transformer just for the fountain pump ($150)
    2. One dedicated 12gauge or lowerLV wire just for the fountain pump ($30)
    3. I only need a pump with about 1000-2000 GPH hour. I checked the wattage. They seem to be less than 100W. 200w+ inverter just for pond pump ($100)
    4. 75w pond pump ($200)

    Would this work better?

    The setup existing pond pump seems to be about $300. I didn't get any quote but to dig up a 24" trench through paver and grass that is deep enough for AC wire and reinstall pavers would seem to cost an arm and a leg.
     

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    johnkim, Jun 1, 2018
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  5. johnkim

    Mmathis TurtleMommy

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    Hello and welcome, but sorry I can’t help — electrical is something I leave to the experts!

    Where do you live? I don’t recognize the flag that shows up in your profile.
     
    Mmathis, Jun 1, 2018
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  6. johnkim

    poconojoe

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    I would stay away from any transformers or inverters. Too costly and not an efficient way of doing things. Everything would need to be waterproof which could end up being very costly for something that might not work out too well anyway. I would look for another 120V power source. If standing where the pond is and looking at your house, that area to the right looks like a path that could be taken. There appears to be grass and maybe shrubs or trees.
    You don't necessarily have to tap into an existing outdoor outlet. If you're handy enough or know someone capable, you can make a connection to any interior outlet thats on an outside wall. You can drill through an inside outlet box and mount a weatherproof outlet box on the exterior of your house. Then run from there via that grassy area.
    Now this has to be done properly with the correct wiring and or conduit. Electricity is nothing to fool with if you don't know what you are doing. Best left to a professional if you have any doubts.
    The other option would be a solar pump, but I don't know how good those are.
     
    poconojoe, Jun 1, 2018
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  7. johnkim

    johnkim

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    Thanks popconojoe.

    What if I just go with a DC powered pump? Do you have any recommendation of a DC pump that can do 1500 GPH?
     
    johnkim, Jun 1, 2018
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  8. johnkim

    Sparky

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    Distance from proposed transformer to pump?
    12 or 24v?
    Are sure we are talking DC lowvoltage? A lot of lighting is step down 24 AC.
    Who told you 24” depth?
     
    Sparky, Jun 1, 2018
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  9. johnkim

    johnkim

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    HI Sparky,

    the 24" is just what I've researched online about AC line burial.

    You're right. I think the low voltage is 12vac rather than 12vdc...
     
    johnkim, Jun 1, 2018
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  10. johnkim

    Sparky

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    So there inverter is out. Btw, not stupid idea. I see where you’re going however, laws of physics and electricity say no. So how to solve? Seeing the property, it is a long way around however 18” is your depth if you can get it. Kid and a sharpshooter shovel, day of labor. Run 12-3 UF. Gives you a spare conductor. Meet it at the house close to existing outside receptacle or where you can get the wire inside. If your handy with electrical you can take it from there. If not do the digging and lay the wire and call one of us. Me? I’d run a sleeve under that drive way. You will be glad you did. When I say sleeve, 2” schedule 80 pvc. It’ll come in handy believe me! Option 1 if I did it all? Completed? That’s everything...750-1000. That’s hooked up and functioning and materials
     
    Sparky, Jun 1, 2018
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  11. johnkim

    johnkim

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    Thanks Sparky. I really appreciate your tips. Will investigate further!
     
    johnkim, Jun 2, 2018
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  12. johnkim

    Sparky

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    Here to help when I can but mostly being guided by these kind folks.
     
    Sparky, Jun 2, 2018
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  13. johnkim

    GBBUDD

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    How old is the driveway ?
    Two simple saw cuts no more then 6" wide will do the job. A ditch witch will get you to depth or make you cut a foot wide and dig it out if you have easy digging soil. sparky correct me if I'm wrong but to run a simple 115/ 15 amp direct burial that should run most fountains including install well from what we know from the house should be around a grand, i'd also plan on upping the amps so you can hook up some x mass lights or what ever may come your way next
     
    GBBUDD, Jun 2, 2018
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  14. johnkim

    Sparky

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    Exactly. Which is why I would go ahead with the sleeve. Those look like pavers to me. Might peel right up. Nowadays, if I bury anything which is almost everyday I run multi conductors. I can justify the extra cost easily and usually costs the customer little or nothing extra. Nothing creates a repeat customer like telling the homeowner we’re already covered when they want to add something. Lately I have been running cable tray wire. Although not it’s intended use, it’s UV rated and the jacket is tough as nails. I keep it on my wire trailer. 12/6 stranded. I can get it in any size.
     
    Sparky, Jun 2, 2018
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  15. johnkim

    johnkim

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    Hi GBBUDD & Sparky,

    Yes, the driveway is paver that is about 20' wide. I think now there are two options to tunnel the driveway. First is using a waterjet tunnel kit. Apparently, it uses water pressure to tunnel through the soil underneath the paver. The second option is to peel up the paver then dig a 16" trench then install a 2" PVC like Sparky recommends.

    What multi conductor will you recommend? Also, if I want to add additional wiring later, can I fish the wire through the PVC pipe easily?

    While I have the trench up, should I install a sprinkler pipe? Is it ok to have it next to the 2" PVC?
     
    johnkim, Jun 3, 2018
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  16. johnkim

    Sparky

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    Now you’re on the right track! Yes, you can run waterline in the same ditch or sleeve under the driveway. Yes you will want access to the sleeve for future use. Since you have the option to later run more stuff, I would get yourself a roll of 12-2 UF cable and run two through there. You might want to up your sleeve to 3”. Make sure it’s schedule 80 pvc.
     
    Sparky, Jun 3, 2018
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  17. johnkim

    poconojoe

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    Just as a note: if you're still going with your original idea of tapping into that existing GFCI, you will be limited to that single existing circuit. What size wire is feeding it and what size circuit breaker? And most likely that GFCI is not the only load on that circuit. So, if you go this route, spare conductors, as suggested, although a good idea, will be useless.
    So, what I'm getting at is feeding you new circuit(s) directly from your circuit breaker panel. This way it will be on a separate circuit dedicated strictly for your new pond. Also those suggested spares will be in your panel for future use.
    Me personally.. I would run a PVC conduit throughout the whole run. I don't mean to put down anyone else's ideas, but I wouldn't use direct burial cable. A 3/4 conduit would allow you to run many individual conductors or at least have the option to add circuits in the future. If you use direct burial cable, you are permanently limited to what you bury. 3/4" PVC conduit and it's fittings are not very costly. You could mount a junction box on the outside of your house and can always tap into that for future use.
    So, where is your electrical panel located in relation to the pond and driveway? Are there any spare spaces open for use in you panel?
     
    poconojoe, Jun 3, 2018
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  18. johnkim

    Sparky

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    Poconojoe is correct about homerunnng to the panel. Conduit the whole way is always better. However, I was looking cost and the givens. Except for well systems and septic fields, the majority of outside wiring I do is SPL (source to pipe to load). Have to up here with frost heaves and rock EVERYWHERE. Ground looks pretty forgiving where you are.
     
    Sparky, Jun 3, 2018
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  19. johnkim

    johnkim

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    Hi popconojoe & Sparky,

    Thanks. I dug 10 feet of trench of 18" depth today and found something interesting. The front yard has a 12VAC line already from the house. I didn't know how the line was buried until I dug it up today.

    It appears to be buried by a 3.5" white PVC pipe running across the driveway. Measuring from the top of the pipe, the depth is about 15" below the ground. If we account for the 3.5" diameter of the pipe, it seems to be buried 18" deep which should be safe and meet the code

    I have two options now:

    1. connect the existing PVC pipe to a new conduit for the new section and bury the new conduit in the trench I dug. Feed 12/3 UF wire through this existing pipe. This will save me time from digging up the 20 feet paver driveway.

    2. dig up the existing PVC pipe and run a new conduit. This will take more time


    What should I do?


    [​IMG]
    The trench is dug up on the grass area. Still need to dig up the driveway

    [​IMG]
    Existing PVC pipe with 12VAC wire

    [​IMG]
    PVC depth from top of the pipe is 15"

    [​IMG]
    PVC diameter is 3.5"

    [​IMG]
    Exit hole of the other side of the PVC
     
    johnkim, Jun 4, 2018
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  20. johnkim

    Sparky

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    Brilliant! Fantastic work. Use that pipe as a sleeve under the drive. Run your waterline through it or anything else since it’s exposed. Run two 12-2s as one could be used for a switch leg or traveler (3way) or spare just in case. That UF can just lay in the ground now that I see your ground exposed. You are golden. White pvc not so much but it’s not being used as a “raceway” just a sleeve. No need to replace. Your depth is fine. Now to get the end to a hot or the panel. Can you sketch me your house with the drive, sleeve, exterior boxes and panel location. You can do this! Legally and safely I might add.
     
    Sparky, Jun 4, 2018
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