250MCM for 21.7 amps? Voltage drop calc must be wrong?

[kwired]

That was actually my first thought (solar panel) but I was concerned about reliability. If there happened to be a few cloudy days and if the gates couldn't open I would be held accountable so I abandoned the idea. I know solar and batteries are getting better but am not up on it. I'll have to research it more so I am informed in the future.

Thanks for the reply BTW

How often does the gate typically operate, sizing the battery to make it through a few cloudy days is probably the most critical part here. The panel will still charge if there is light, just may not be at as high of a rate as with full sun.

 

[Cloud]

Sure it is, even if you already have three phase 480 volt system - take any 2 conductors besides a neutral to a load and you essentially only have 480 single phase available to that load.

Most of the discussion on 480 volts has been about stepping up with a single phase transformer.

But yes of course. L to L. What I'm trying to say if it is a single load, can it still be possible?

 

[Cloud]

But yes of course. L to L. What I'm trying to say if it is a single load, can it still be possible?

sorry wasn't able to read all the posts. If he will use motors on the guard house bars, will 480 1 PH motor be readily available?

 

[kwired]

sorry wasn't able to read all the posts. If he will use motors on the guard house bars, will 480 1 PH motor be readily available?

The intention of sending 480 volts over the long distance was to minimize voltage drop, there was still going to be transformation back to 120 volts at the load end.

 

[Bri22]

I like the 600 volt idea with the exception mentioned so you dont need the EGC - just two wires. Here is an example of some transformers, not sure how good the price is.
http://www.transformeronline.com/product/600v-120240v-single-phase-transformers/

Use aluminum wire. For the 120 V option, say 20 amps = 350 URD aluminum (2 X 350 USE/RHH plus 1 X two size reduced neutral/ground) is $3 per foot, keeps you around 4% drop. With 600 volts, you would just need 2X #6 aluminum which is about .20 per conductor per foot, plus smaller pipe as a bonus. So save $3500 on wire, a little more on smaller pipe, but have to pay a grand for the two transformers. Still seems worth it.

Another option I didn't think of. I guess I just always use copper so I never thought of it. Thanks

 

[kwired]

Didn't crunch any numbers but if there is 120 volts at the source end then there is likely 208 or 240 volts there as well - can possibly save cost of one transformer and needed accessories but still need a larger conductor then needed for 480 or 600 volts if you ran a 208/240 feed to the remote location then transform to 120 volts.

 

[Bri22]

How often does the gate typically operate, sizing the battery to make it through a few cloudy days is probably the most critical part here. The panel will still charge if there is light, just may not be at as high of a rate as with full sun.

I'm not sure exactly but the gates will probably open several hundred times per day. There is also communication equipment out there, video/intercom, card reader and license plate reader.

 

[Bri22]

Didn't crunch any numbers but if there is 120 volts at the source end then there is likely 208 or 240 volts there as well - can possibly save cost of one transformer and needed accessories but still need a larger conductor then needed for 480 or 600 volts if you ran a 208/240 feed to the remote location then transform to 120 volts.

The source is 120/208 3phase. I'm pretty sure were going to bump it up to 600 volts because I want to keep the wire as small as possible for that long of a run. I have never pulled wire that far but I'm pretty sure a #10 or #8 could be pulled with a couple guys. Other wise I'm going to have to invest in a tugger and some bigger wire real stands.

 

[electrofelon]

Another option I didn't think of. I guess I just always use copper so I never thought of it. Thanks

For the 120 volt option price out both cu and AL and ask yourself which one you would go with if you were paying for it :happyno: for 600 volt the wire is small enough it may not be a big deal. Actually #6 AL was even overkill but it's the smallest size commonly available around here.

 

[kwired]

I'm not sure exactly but the gates will probably open several hundred times per day. There is also communication equipment out there, video/intercom, card reader and license plate reader.

Sounds critical enough that reliability will get some priority then and so would cost to have it.

If you need to dig a trench anyway, you have a lot of options of what to put into it. Maybe even let POCO bring their primary out there (they should have primary close enough to your supply end anyway) and set you a single phase service out near the gate. 7200 volt line will not have any voltage drop issue for the load being served.

One concentric MV cable, one fiber optic cable, install with plowing method, unless soil conditions are not favorable for that, would be fastest and least destructive to landscape. May even be able to put them in with one pass.

 

[electrofelon]

The source is 120/208 3phase. I'm pretty sure were going to bump it up to 600 volts because I want to keep the wire as small as possible for that long of a run. I have never pulled wire that far but I'm pretty sure a #10 or #8 could be pulled with a couple guys. Other wise I'm going to have to invest in a tugger and some bigger wire real stands.

I would probably sleeve it for that length. Just reel out the conductors and glue up 40 feet at a time and walk it down

 

[Bri22]

The source is 120/208 3phase. I'm pretty sure were going to bump it up to 600 volts because I want to keep the wire as small as possible for that long of a run. I have never pulled wire that far but I'm pretty sure a #10 or #8 could be pulled with a couple guys. Other wise I'm going to have to invest in a tugger and some bigger wire real stands.

The source for the gates is also a new panel at a guard house away from the main buildings. Now that I'm thinking about it, I think I'll ask the engineer change that to 480. It will make that wire smaller to. It's not as long as a run as the gates but it's still around 350 feet. I think it would be worth it.

 

[kwired]

I would probably sleeve it for that length. Just reel out the conductors and glue up 40 feet at a time and walk it down

You can come help run lines for center pivot irrigation - have done exactly that process for nearly 30 years now. Though the "walk it down" is sped up considerably by going 60 -100 feet at a time and using an ATV to help you along.

They also make cable in conduit - conductors already installed in HDPE conduit - but on huge reel and I have to go about 80 miles and back to the nearest place that stocks it. I have used it a few times but if you don't have the right equipment to handle those huge reels the other method still works out better in the end. Between the higher cost per foot of CIC, having to pick it up, my other supplier can deliver conduit and wire directly to site if I want, and heavy equipment needed to handle the CIC - I still stick to the old way of doing it. If I did a lot more of these installs maybe buying the needed equipment would be worth while.

 

[jumper]

Sorry dont know how to rotate the image.

I do.

View attachment 14353

 

[Cloud]

I would probably sleeve it for that length. Just reel out the conductors and glue up 40 feet at a time and walk it down

Have powered a metmast using also manual pulling, with some rollers and a lot of workers. actually, this is the same process we are doing even for MV up to 630mm² and FO, not efficient but opted to that method since cost of labour here is cheaper than hiring a dedicated equipment- reeling it out at the middle and pulling both ways.

 

[Bri22]

I would probably sleeve it for that length. Just reel out the conductors and glue up 40 feet at a time and walk it down

Sounds like a good idea. Just need to be careful to keep the dirt out.

 

[Cloud]

I do.

Thanks! But those calculations are useless now, since that is for a 3% VD tolerance.

 

[jumper]

Thanks! But those calculations are useless now, since that is for a 3% VD tolerance.

I am not really participating here, I was just skimming through scanning the thread.

Use paint to rotate your pics if needed.

 

[JFletcher]

I would probably sleeve it for that length. Just reel out the conductors and glue up 40 feet at a time and walk it down

Is that compliant with 300.18(A)? (2008 NEC)

 

[electrofelon]

Is that compliant with 300.18(A)? (2008 NEC)

Correct. Sleeving is technically not code compliant. I'm ok with violating that one.