Need to run electric for NINE water trough heaters

[GPintheMitten]

I need to help my daughter run electric to 9 water troughs to power trough heaters for the winter in Michigan. Her heaters are 1500 watts each. That's 12.5 amps each for a total of 112.5 amps. This is going to be a challenge to do it in the most economical way. Not only are the total amps high but the runs are long. We are going to bury the wire in trenches when we install buried water lines to frost free hydrants in the same project.

I'm going to attach a rough diagram to show the placements.

I'm going to need to replace the subpanel in the barn to support this but that's not my problem. I've done that before. I'll check the exact wire gauges that supply the barn and size the feeding breaker in the main panel and the main breaker in the sub. But at first glance it looks to be pretty heavy guage aluminum but is only on a 60 amp breaker now. I'm hoping the existing wire to the subpanel will be large enough for a 150 or 125 amp subpanel. If not, I'll need to get my daughter to decrease the number of heaters. I would rather not have to re-feed the sub panel.

Anyway. The reason I'm posting, is that I could use your ideas on how best to supply all this in the pastures. Typically 10 guage will support 30 amps will will handle 2 heaters with some spare but the runs are long. I know I can up size to avoid voltage drop.

After looking at my diagram attached. How would I best supply the 4 heaters on the right (marked A, B, C, and D totalling 50 amps draw)? Run a 3 wire with ground to location A, attaching 2 to A and B, then running the other hot to C then D along with neutral and ground? The total run for the neutral would be 830 feet. This would be supplied by two, 30 amp single pull breakers (120 volt).

The group on the left totals 62.5 amps with a total of 890 feet.

I am aware of some heaters that are 1200 watts (10 amps) so that might have to factor into this.

Just as background, I know how to wire and have done several subpanels, a main panel and wired a previous house that I owned... all with permits and inspections. What I'm trying to figure out is a strategy to keep the wire costs down to a reasonable cost. I could home run a 10-2 w ground for each heater but that might not be the best way to go and may be more expensive than other options.

Sorry for long post. Ideas? Suggestions?

 

[dave1949]

How "future" is the future barn and what will its electric supply be?

If it will have its own service drop and/or meter, then maybe you could put that in and use a temporary construction site-type pole & panel for the heaters. If that worked, then you would save on heater wire, and save on changes to the existing barn panel to offset the cost. Eventually, that money will be spent on the new barn electric anyways.

 

[RedNeckRacin]

Your not going to do it cheaply to run that kind of distance. I believe that there are some calculators on the internet that would help to work things out.

I did a quick google search and came up with a 25 amp load at 830 feet for simplicity sake, and got 2/0 AWG for that run using 120v single phase.

Runtime Error I don't even know if that is accurate but its a starting place.

 

[GPintheMitten]

Thanks Dave. I'm not sure. My daughter wants the new barn before winter but her husband doesn't think it is affordable right now. Maybe in a year or two. And I don't know if it would be cheaper or not to have its own service drop, but maybe. There is so much to consider on this whole venture.

How "future" is the future barn and what will its electric supply be?

If it will have its own service drop and/or meter, then maybe you could put that in and use a temporary construction site-type pole & panel for the heaters. If that worked, then you would save on heater wire, and save on changes to the existing barn panel to offset the cost. Eventually, that money will be spent on the new barn electric anyways.

 

[GPintheMitten]

Thanks RedNeckRacin. I agree this is going to cost a lot. I'm seeing a need to up size a lot more than I anticipated earlier. Thanks for the link to the calculator.

Your not going to do it cheaply to run that kind of distance. I believe that there are some calculators on the internet that would help to work things out.

I did a quick google search and came up with a 25 amp load at 830 feet for simplicity sake, and got 2/0 AWG for that run using 120v single phase.

Runtime Error I don't even know if that is accurate but its a starting place.

 

[GPintheMitten]

Anyone know what might be an acceptable voltage drop for these electric trough heaters?

Anyone know of the best place to buy direct bury wire? I'm going to need some spools up to 500' assuming I use a junction box to splice. If no spice then I'll need up to 850' foot.

 

[boggen]

copper vs aluminum, and distances you have, ya might try the bigger size aluminum. the only issue is corrosion at your end connectors.

looks like...

house panel -> barn panel -> sub panel (left side), (sub panel right side)

then again your getting up in so many amps... the service upgrade on both house and barns.... might be better off with new service line to a central area. and splitting the house completely off of everything else. (getting billed separately for house, getting billed separately for everything else) pending on how electrical company wants to do it for billing.

also ya going buried vs over head wires... which may bring up cost / size of wire needed. from direct burial, to piped in, to a single combined wire (that has all the wires in it you need)

water line and electrical = not in same trench, at least for codes around here. they need to be split apart by so many feet, (when running parallel) water line most likely going to be deeper to get below frost depth, and electrical most likely going to be closer to surface (do to not needing to worry about wires freezing).

you talking 550 feet in one run... that is pretty good length of run. plus a good amount of length in other runs. if you had a machine that could trench it all up, lay down your pipes for water, and pipe of going with pulling wire through some pipe. you might have some better luck off setting some cost and ease, letting a 3rd party company pull the wires for you. 3rd party company more likely to bring in a big spool of wire and machine to handle it, and just start unraveling it off for each long pull. water hose is one thing, but electrical wire *WOW* that stuff gets heavy quickly.

==========
*rubs chin* i actually would call electric company, most likely they will send someone out, at least they have here over the years and free of charge. and walk through cost of this vs that. and different options. what is needed and were.

i realize diagram is all good. but someone able to actually step foot and see trees, fence lines, barns, etc... and have knowledge of this and that plus knowledge of local codes. can go a long ways

 

[RedNeckRacin]

I'm not sure what the acceptable drop is, but v=ir and the less voltage you have the less your going to get out of those heaters. The calculators I looked at said a 3% voltage drop was acceptable. I don't know if that's a good window or whether you can stretch that a bit. I'm not an electrician by any means but I had to double up some wires due to a shortcut by someone else to run some 1500w water trough heaters.

 

[CobyRupert]

Assuming you have a 120/240 single phase panel, here's a couple notes :

Remember, with single phase your circuit distance is twice the cable distance ( i.e. "to" and "back")
Also remember, voltage drop in a resistive heating element isn't a big deal. Usually it's no problem if a heater gets, say 90 volts instead of 120v, then the 1500W heater is a 843.75 Watt heater. It's just going to run longer.

1. Can you run the heaters at 240V, then they'd only draw 6.25 amps each?
2. If not, run a 3 wire 240V circuit consisting of L1-Blk wire, L2- Red wire, Nuetral-wht wire) (& gnd -green wire (not counted)) from a double pole breaker (i.e. must have 1 handle), yet connect 2 of 120V heaters from L1-N and the other 2 on L2-N. Each hot conductor (L1 & L2) will only see the current of two heaters (25 amps).
When all 4 heaters are on, the current in the neutral is ZERO. The maximum current the neutral could ever see is when only 2 heaters on 1 "leg" are on and the other 2 on the other leg are off, then the neutral sees 25amps (and your voltage drop gets worse because now the current is traveling twice the distance (i.e. "to" and "from").

 

[JPRambo]

Do they all have to be "on" at the same time? Could you use timers for them to be on long enough to thaw the water and turn off. Then the next heater come on, thaw turn off and the next, etc...