Anonymous-0
Well-known Member
I have an out building about 700 feet away from any power source,would like to put a couple lights and maybe 3 outlets in ,can I run a 12-2 wire out that far,if so should I put a small breaker box in it? any info thanks
- Thread starter Anonymous-0
- Start date
There are several electrical gurus on here that answer this question about every other month, so be nice to them even if they are a little short with the answer - again and again. 
The answer will be no. 12 won't even be _close_, you are looking big fat wire for 700 feet - even for 'just' 20 amps.
And you _do_ need some sort of breaker box in the building. You even need to be feeding from a breaker wherever you are coming from.
You'll find you have to dig the trench, buy the boxes, and do all the labor anyhow and buy fatter wire anyhow - it would be _really_ smart to plan for a 60 amp box out in the building, and burry wire that will support 60 amp right from the get go. Yes you will have sticker shock on the price of the wire, but then it is done right and will do what you need to do.
In today's code, you likely need to run _four_ wires out there to get 220v, or 3 wires to get 120v. You need the ground, the nuetral, and one hot (for 120) or 2 hots (for 220v).
The nuetral & ground are _not_ the same and _can't_ be interchanged and we just had that discussion a couple days ago.
Good luck with the planning & work.
--->Paul
The answer will be no. 12 won't even be _close_, you are looking big fat wire for 700 feet - even for 'just' 20 amps.
And you _do_ need some sort of breaker box in the building. You even need to be feeding from a breaker wherever you are coming from.
You'll find you have to dig the trench, buy the boxes, and do all the labor anyhow and buy fatter wire anyhow - it would be _really_ smart to plan for a 60 amp box out in the building, and burry wire that will support 60 amp right from the get go. Yes you will have sticker shock on the price of the wire, but then it is done right and will do what you need to do.
In today's code, you likely need to run _four_ wires out there to get 220v, or 3 wires to get 120v. You need the ground, the nuetral, and one hot (for 120) or 2 hots (for 220v).
The nuetral & ground are _not_ the same and _can't_ be interchanged and we just had that discussion a couple days ago.
Good luck with the planning & work.
--->Paul
Gonna need 4 conductor wire for that, Neutral (white) and the bonding(green or bare)wire. They can only meet in the main panel. Aluminum wire is cheaper use SER cable and run it in PVC pipe with a sub panel in the garage. wouldn't hurt to drive a ground rod either. use number #4 awg.
And I'm gonna catch hell for posting an answer.
And others will have different opinions on how to do it.
Good luck
Jim K
And I'm gonna catch hell for posting an answer.
And others will have different opinions on how to do it.
Good luck
Jim K
http://www.elec-toolbox.com/calculators/voltdrop.htm
This site is a bit dramatic, some say it goes overboard giving you a wire for a 3% voltage drop, while 5% is allowed and would use a smaller wire.... True, but you are going to have wires running through the building yet, so the wire will be longer, accounting for another % or 2 of drop perhaps..... There are other calculators online, might want to find a less conservative one if you want to skimp a bit.
If you plug in your numbers, you will find that running a 240v run out there will probably be cheaper than trying to get anything useable at 120v..... Looks like you'd only get 2 amps or less useable at such a long distance on a #12 wire!
--->Paul
This site is a bit dramatic, some say it goes overboard giving you a wire for a 3% voltage drop, while 5% is allowed and would use a smaller wire.... True, but you are going to have wires running through the building yet, so the wire will be longer, accounting for another % or 2 of drop perhaps..... There are other calculators online, might want to find a less conservative one if you want to skimp a bit.
If you plug in your numbers, you will find that running a 240v run out there will probably be cheaper than trying to get anything useable at 120v..... Looks like you'd only get 2 amps or less useable at such a long distance on a #12 wire!
--->Paul
No way . Run at least 6 gauge 4 conductor cable & set a small branch panel with breakers plus drive an 8' ground rod outside . As I've seen in the past , guys want to do what you wanted for just lights & 1 or 2 recepts . Then pretty soon they see how convenient it is to have electric out there & then they decide , hey I'll put a welder out here or maybe a couple wood working machines . Then they start popping breakers or fuses & wonder why . Good theory is to always think ahead when doing this . Sit down & figure, now what all possibilities can I use the building for , then figure out what draw you'd have . Then wire accordingly .I plan on running a branch feed overhead from my garage to my small barn/machine shed eventually .I'm doing it in steps as I can afford it . I've set one pole & need to set one more .Its about 200' . I only plan on having about 8 recepts & about 4 overhead lights . But just incase I need to do some welding & grinding up there & too I may decide to install an outside security yard lite so I'm going to run #2 triplex . Also remember to drive an 8' ground rod at each building for that additional ground . Safety is a #1 key for you & insurance purposes .Wiring will be expensive but please don't take short cuts & regret it later .Never leave any electrical boxes uncompleted or open .HTH ! God bless, Ken
Anonymous-0
Well-known Member
At 700 feet, the voltage drop will be so bad that your "60 amp" service will hardly be a true 20 amp service.
Gerald J.
Gerald J.
Doug Steinbach
Member
You definately need to run 4 conductor wire, in conduit, and do not use SER cable, it is not rated to be in wet conditions and you will have water in the conduit - I promise.
You can certainly use aluminum, but no matter what you do it won't be cheap. Aluminum URD will be the cheapest but you will have to buy another conductor to put with it to use for ground as URD is only 3 conductor.
If you would like I can do the calculation for you, once I go back to my office tomorrow, and let you know what size wire you need. As others have suggested I would plan to put at least 60 amps out there.
You can certainly use aluminum, but no matter what you do it won't be cheap. Aluminum URD will be the cheapest but you will have to buy another conductor to put with it to use for ground as URD is only 3 conductor.
If you would like I can do the calculation for you, once I go back to my office tomorrow, and let you know what size wire you need. As others have suggested I would plan to put at least 60 amps out there.
buickanddeere
Well-known Member
To be "legal" with 5% voltage drop with 120V, 15 amp load at 700ft. The code book says #4 copper cable.
So four conductors of #4 copper will provide the same power at the shed as a split receptacle in your kitchen. Two 15amp 120 circuits or one 240V 15amp circuit.
Paul is correct that 12/2 at 700ft is rated for 2.5 amps.
The solution would be to save a couple of 10kva single phase air cooled transformers. 120/240V to 480V or better yet a 120/240V to 600V.
Step 240V up to 600V at the main service. Run 600V out to the shed. Step the shed 600V back down to 120/240V.
12/2 gauge 700ft feed with 600V out to the shed would operate four 120V 15amp receptacles or one 30amp 240V receptacle.
So four conductors of #4 copper will provide the same power at the shed as a split receptacle in your kitchen. Two 15amp 120 circuits or one 240V 15amp circuit.
Paul is correct that 12/2 at 700ft is rated for 2.5 amps.
The solution would be to save a couple of 10kva single phase air cooled transformers. 120/240V to 480V or better yet a 120/240V to 600V.
Step 240V up to 600V at the main service. Run 600V out to the shed. Step the shed 600V back down to 120/240V.
12/2 gauge 700ft feed with 600V out to the shed would operate four 120V 15amp receptacles or one 30amp 240V receptacle.
Just the typical farm wiring job around 'here' - they stop measuring the wire in 'gauge' any more and start using lots of 'M' & 'C' type letters. My farm has several runs 300-500 feet long to get to all the buildings, 200amp about 2/3 of the way, 60 amp to the ends.
The wire is about as thick as my thumb - not counting the insulation!
Whatcha gonna do? Gotta have power.
There _is_ an ag exception to the rule of needing 4 wires, if the remote building is considered it's own service - in some locations. So depending on location, he might be able to run 240v out there with 3 wires. All depends on the local inspectors....
--->Paul
The wire is about as thick as my thumb - not counting the insulation!
Whatcha gonna do? Gotta have power.
There _is_ an ag exception to the rule of needing 4 wires, if the remote building is considered it's own service - in some locations. So depending on location, he might be able to run 240v out there with 3 wires. All depends on the local inspectors....
--->Paul
Anonymous-0
Well-known Member
Yes it will supply loads with three wires on 240, but it may also kill the user of a metal cased tool if the neutral breaks or corrodes in two as aluminum will if the insulation is breached. Also an aluminum neutral connection overstressed by a shorted cord can sometimes go open. And I've seen both happenings kill the tool users, more than once. I wasn't there. I had to investigate why and explain it to the survivors and their insurance companies. Sometimes to a jury. So I'm more than a little picky about that fourth wire.
After 4/0 wire common wire sizes are 250 MCM, 300 MCM, 350 MCM, up to 4000 MCM usually in 50 MCM steps... 250,000 circular mils cross section. M for 1000, CM for circular mils cross section. A circular mil is a wire .001" diameter having an area of pi/4 mil squared. So a solid conductor 250,000 CM would be 0.500" diameter. A stranded conductor is larger because of the air spaces between the strands. Circular mils are a little more logical than wire gauges (different for iron than copper, and different for different countries), but are a short hand ignoring the pi/4 factor by simply squaring the diameter.
After doing a 4/0 wiring job, I set my limits at 0, hire someone else for the larger sizes, they take tools I don't have and muscles too.
Gerald J.
After 4/0 wire common wire sizes are 250 MCM, 300 MCM, 350 MCM, up to 4000 MCM usually in 50 MCM steps... 250,000 circular mils cross section. M for 1000, CM for circular mils cross section. A circular mil is a wire .001" diameter having an area of pi/4 mil squared. So a solid conductor 250,000 CM would be 0.500" diameter. A stranded conductor is larger because of the air spaces between the strands. Circular mils are a little more logical than wire gauges (different for iron than copper, and different for different countries), but are a short hand ignoring the pi/4 factor by simply squaring the diameter.
After doing a 4/0 wiring job, I set my limits at 0, hire someone else for the larger sizes, they take tools I don't have and muscles too.
Gerald J.
Thank you for the explination of the lettering system of those big wires! Appreciate that. Never quite knew what they ment, other than 'spendy!'
I had the pros redo my wiring, and of course inspected. Everyone was happy with the 3 wire & grounding rods setup.
Those are sure some stiff wires to work with! Al of course.
--->Paul
I had the pros redo my wiring, and of course inspected. Everyone was happy with the 3 wire & grounding rods setup.
Those are sure some stiff wires to work with! Al of course.
--->Paul
Anonymous-0
Well-known Member
It would cost less to move the building.
John M
Well-known Member
- Location
- Nunyafn business
Id call the power company and see what heyd charge to run a line out there.
Anonymous-0
Well-known Member
I am NOT a fan of the local ground wire replacing the fourth (ground) wire. A local ground may have too much resistance to divert current away from the operator of a tool to save him from shock, whether that shock is annoying or deadly it can cause a lot of damage if the tool happens to be a Skil saw and the shock causes it to saw into a body part because the shock took away muscle control which is what electric shock not strong enough to upset the heart does.
Its no fun to have to explain to the widow and kids that another $37 spent on another bit of wire could have prevented the shock.
Gerald J.
Its no fun to have to explain to the widow and kids that another $37 spent on another bit of wire could have prevented the shock.
Gerald J.
Walt Davies
Well-known Member
Personally I would call the local power company it might save you some to put in another service to the barn the minimum charge would be less than the cost of installing a lot of heavy wire. If the have a line close by then it won't cost anything or very little for the drop.
Walt
Walt
In a three wire setup the return path for fault current to the service transformer (grounded neutral) is tested each and every time the lights are turned on in the outbuilding. The wire gauge is also larger. In a four wire setup the fault current return path (green/bare)is only tested when it is needed. After 30 years it may not be there or the connections maybe loose, you never know. An added bonus of three wire is that the neutral will be anchored to ground at the end of a 700ft run.
I have alot of respect for you Gerald I am not argueing just something that I have thought about.
I have alot of respect for you Gerald I am not argueing just something that I have thought about.
buickanddeere
Well-known Member
The neutral is not "anchored" at the end of the 700ft run. We have discussed "ground loops" here for a couple of years now and people still don't get it.
The only bond for the service neutral is at the main panel. Remote and pony panels are not to bond the neutral to ground. The neutral floats.
Otherwise the ground system will start carrying neutral current. That is a problem.
The only bond for the service neutral is at the main panel. Remote and pony panels are not to bond the neutral to ground. The neutral floats.
Otherwise the ground system will start carrying neutral current. That is a problem.
NEC permitted just what I was talking about until the past revision. If the remote panel was in a different structure it was permitted to feed three wires to the panel and ground the neutral at the remote panel. Been done across the country and inspected millions of times by the authorites. For one example see Paul's post above. I have read these boards enough to know that if he does something or has it done it is right.
Which is less resistance? 700ft of earth or 700 feet of cu/al wire.
Which is less resistance? 700ft of earth or 700 feet of cu/al wire.
buickddeere
Member
The code book was revised because the remote ground bond to the neutral causes neutral current to flow in the grounding system.
The code book also used to allow two conductor wiring without a ground wire. And two prong 120V/15amp household receptacles.
So it was wrong then and it's wrong now to bond the neutral to earth at a remote or pony panel.
The code book also used to allow two conductor wiring without a ground wire. And two prong 120V/15amp household receptacles.
So it was wrong then and it's wrong now to bond the neutral to earth at a remote or pony panel.
buickddeere
Member
Doesn't matter soil or cable, a path is a path.It's a ground loop.
In particular should the neutral go open. Now everything "grounded" at the remote panel is live.
So, don't bond the remote neutral to the earth.
Is this a pride thing about who is correct? Or is this about proper wiring?
In particular should the neutral go open. Now everything "grounded" at the remote panel is live.
So, don't bond the remote neutral to the earth.
Is this a pride thing about who is correct? Or is this about proper wiring?
I see I"m not going to get an answer from you in regards to the ground loop.
As far as the open neutral is concened, there are a few things to think about. Like I originally posted would you rather know that your safety is working everytime you turn on the switch and risk an open neutral that may or may not cause you shock if it happens depending on the quality of the ground bond. (Human in parallel with copper) Or have a safety system that is only tested when you need it most. (4 wire). The service drop feeding most everyone"s house is a three wire setup, grounded at both ends. We live with that risk everyday. At the turn of midnight from 2007 to 2008 (new NEC) an acceptable method of wiring became improper?
Look I"m not advocating that people not run 4 wire setups, or go against the code. I would certainly advise somebody that is doing a new installation fo follow the current code. I will admit that you annoyed me when you plastered "wrong" all over everything and asserted that were was only one correct way to do the job. Whether you use three or four wire is a matter of which safety compromise you wish to make. They are both proper. Before you get bent out of shape when I said "safety compromise" there are things involving electricity and safety that are a compromise. The safest thing to do is stay in bed or not even have electricity in your house.
Yes by all means, follow the current code and run four wires. But don"t say something is wrong when it isn"t. I will let you have the last word. Good evening and best wishes.
As far as the open neutral is concened, there are a few things to think about. Like I originally posted would you rather know that your safety is working everytime you turn on the switch and risk an open neutral that may or may not cause you shock if it happens depending on the quality of the ground bond. (Human in parallel with copper) Or have a safety system that is only tested when you need it most. (4 wire). The service drop feeding most everyone"s house is a three wire setup, grounded at both ends. We live with that risk everyday. At the turn of midnight from 2007 to 2008 (new NEC) an acceptable method of wiring became improper?
Look I"m not advocating that people not run 4 wire setups, or go against the code. I would certainly advise somebody that is doing a new installation fo follow the current code. I will admit that you annoyed me when you plastered "wrong" all over everything and asserted that were was only one correct way to do the job. Whether you use three or four wire is a matter of which safety compromise you wish to make. They are both proper. Before you get bent out of shape when I said "safety compromise" there are things involving electricity and safety that are a compromise. The safest thing to do is stay in bed or not even have electricity in your house.
Yes by all means, follow the current code and run four wires. But don"t say something is wrong when it isn"t. I will let you have the last word. Good evening and best wishes.
buickddeere
Member
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