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

[johnkim]

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?

 

[Sparky]

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?

 

[poconojoe]

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.

 

[johnkim]

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.

 

[Mmathis]

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.

 

[poconojoe]

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.

 

[johnkim]

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?

 

[Sparky]

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?

 

[johnkim]

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?

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...

 

[Sparky]

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...

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

 

[johnkim]

Thanks Sparky. I really appreciate your tips. Will investigate further!

 

[Sparky]

Here to help when I can but mostly being guided by these kind folks.

 

[GBBUDD]

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

 

[Sparky]

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

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.

 

[johnkim]

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?