Up the hill

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petersonra

petersonra

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Northern illinois
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Semi-retired engineer
There was an interesting post during the night from a guy asking for advice on how to run power a thousand foot up a hill. It seems to have been deleted because it was from some kind of non-electrician. But I thought it was interesting. Just curious how you guys would go about it.

Not even 15 amps at 120 volts.

Conduit laid on the surface? Poles? Buried cable?
 
I used to have a 1kw wind turbine at the top of my hill, about 1300 feet away. I used 10-2 UF laid on the ground. I intended to bury it but never got around to it. It was problematic because Rodents would nibble on it and it shorted out a few times.

I have mentioned this in the past here but the brown bed edger is a great tool for burying small cables and conduits if you don't need to go real deep. I have one. Super low impact, cuts thru roots pretty good and you can weave around trees.

TrenchMaster

brownproducts.com brownproducts.com
 
the post is still there. this bed edger, is not a ditch witch, so would be great for small stuff. I am not a fan of ditch witches. I dug thru 7200 volt primary feeding a hospital as the old guy running the job wanted me, the young guy running the machine to go a bit deeper. The POCO showed up and he went to lunch
 
petersonra said:
There was an interesting post during the night from a guy asking for advice on how to run power a thousand foot up a hill. It seems to have been deleted because it was from some kind of non-electrician. But I thought it was interesting. Just curious how you guys would go about it.

Not even 15 amps at 120 volts.

Conduit laid on the surface? Poles? Buried cable?
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I think it depends on what the hill is made out of.....is it rock? Dirt? Is it a soil cap on a superfund side you wouldn't want to be digging in?
 
jimport said:
Don't you need to consider voltage drop if it runs downhill instead of uphill?
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Not just voltage drop, but also the time it takes for the breaker to open during a fault.

14, 12 and 10 gauge wire are nothing more than elongated resistors.
 
petersonra said:
There was an interesting post during the night from a guy asking for advice on how to run power a thousand foot up a hill. It seems to have been deleted because it was from some kind of non-electrician. But I thought it was interesting. Just curious how you guys would go about it.

Not even 15 amps at 120 volts.

Conduit laid on the surface? Poles? Buried cable?
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#2 alum triplex (or duplex if you can find it) laid up and tied in the trees or laid bare through the woods for something real simple.
Its relatively inexpensive and easy enough to splice
Turn it off when I’m not there.
I have ran 200’ #2 before to run a house for a night or two to temporary a bad underground service
 
petersonra said:
There was an interesting post during the night
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IIRC, he wanted to feed 1000ft #4 AL USE cable, as 240v MWBC, and splice box for 2 convenience duplexes.

That feeder hits 3% VD after 8 Amps at unity, if loads are balanced on both outlets. Of course thats 6% VD going up hill against gravity.

tom baker said:
I dug thru 7200 volt primary feeding a hospital as the old guy running the job wanted me, the young guy running the machine to go a bit deeper. The POCO showed up and he went to lunch
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You are a walking miracle. How does anybody survive cutting into 7200 volts?
 
Hv&Lv said:
#2 alum triplex (or duplex if you can find it) laid up and tied in the trees or laid bare through the woods for something real simple.
Its relatively inexpensive and easy enough to splice
Turn it off when I’m not there.
I have ran 200’ #2 before to run a house for a night or two to temporary a bad underground service
Click to expand...
Table 310.17 says 1000ft #2 AL triplex 240v on messenger hits 3% VD after 13 Amps
 
ramsy said:
Table 310.17 says 1000ft #2 AL triplex 240v on messenger hits 3% VD after 13 Amps
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Correct, but what does that matter? Your not limited to 3%. If you want to go to 10%, what’s stopping you?
So if you have 124 you end up with 120 or 121. I wouldn’t worry about 4 volts anyway.
If this was 1950 as long as your above 115V, your good to go.
Plus we would be griping about high voltage at the end if it ends up being 120
 
ramsy said:
IIRC, he wanted to feed 1000ft #4 AL USE cable, as 240v MWBC, and splice box for 2 convenience duplexes.

That feeder hits 3% VD after 8 Amps at unity, if loads are balanced on both outlets. Of course thats 6% VD going up hill against gravity.


You are a walking miracle. How does anybody survive cutting into 7200 volts?
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A friend of mine dug thru a MV line with a mini ex early this year. I am not sure of the voltage. He didnt even know he dug thru it until he saw the wire sticking out into the ditch.
 
ramsy said:
You are a walking miracle. How does anybody survive cutting into 7200 volts?
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I have cut a 13.2 kV line with a pair of circle cutters years ago. If it hadn’t spit a time or two I wouldn’t have known it.
We didn’t have cable spikes back then. The MV cable has a concentric neutral around it, so your basically providing a “bolted” fault path when you cut it.
MOST people that cut these lines with a piece of equipment assume they are no good because there isn’t a big flash and a fire. Unless you hear a fuse blow its doubtful you will know until the POCO shows up, or you just assume you’ve cut a good line and call in…
 
Although I am often against these transformer step up/step down schemes, they do sometimes have their place. This may be one of them. What people often dont think about is, its not just about the cost of the wire and equipment, but the trenching requires consideration too. For example, if you can keep your wire in a 1/2 or 3/4 pipe, then you can use that brown mini trencher and avoid a potential trenching nighmare where you are on a steep slope and have to clear a bunch of trees just to get the machine through, etc. If 600V doesnt do, it, use PV wire and go up to 2KV. Some #12 PV wire goes a long way at 2KV. That brown will go code compliant for IMC/RMC, or just use PVC if you dont need code compliance.
 
Hv&Lv said:
If you want to go to 10%, what’s stopping you?
So if you have 124 you end up with 120 or 121. I wouldn’t worry about 4 volts anyway.
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124v minus 10% VD is ~111.

IIRC they wanted IT equipment atop hill.

Switch mode power supplies shut down below ~105v, as shown on equipment nameplate.

Those pesky computers, TV's, & just about all electronic appliances nowadays have similar nameplates.
 
Hv&Lv said:
I have cut a 13.2 kV line with a pair of circle cutters years ago. If it hadn’t spit a time or two I wouldn’t have known it.
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I heard those concentric neutrals are the first to get corroded away over time. What happens if you hit a spot missing the neutral?

My area enforces Dig Alert (811), which makes sure all utilities mark their lines before we're allowed to dig.

Contractor's who don't notify dig alert are liable for damages & casualties.
 
electrofelon said:
..if you can keep your wire in a 1/2 or 3/4 pipe, then you can use that brown mini trencher ..use PV wire and go up to 2KV..
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Is there a table for 2000 volts?

Table 300.5 only goes up to 1000 volts, but column 2 allows 6" for RMC & Sch-80, and your mini trencher is rated for ~7" deep.
 
ramsy said:
124v minus 10% VD is ~111.

IIRC they wanted IT equipment atop hill.

Switch mode power supplies shut down below ~105v, as shown on equipment nameplate.

Those pesky computers, TV's, & just about all electronic appliances nowadays have similar nameplates.
Click to expand...
I understand that.
10% was an arbitrary number..
What I’m trying to convey is to not get hung up on the 3% VD. Pushing VD to 4.3, or 5.7% is fine..
 
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