# Wire gauge for 150 ft run



## sinclair1

I want to run power to a dock. Circuit is alone and was just a receptacle and light in a crawl space. I want to just use the wire you can just bury and not encase in conduit, but not sure about gauge for a run that long. I could go straight and save distance if needed but want to run along the fringe ( long way). If possible I would like a light in the middle of the run ..good idea or bad for a run that length?
I am not there so not sure of open spaces. Currently use the wire that ran from the T pole at build and just plug in a recepticle but that bootleg deal is failing as it was indoor wire just run above ground.


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## Horns

It doesn't sound like you plan on having a big load overall but more worried about voltage drop.


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## Jake Allen

How many watts of power will be needed?


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## sinclair1

Jake Allen said:


> How many watts of power will be needed?


Just regular light duty, maybe a radio, a LED light that doesn't stay on all the time, but half way maybe a dusk to dawn light if possible.


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## jimbo4116

sinclair1 said:


> Just regular light duty, maybe a radio, a LED light that doesn't stay on all the time, but half way maybe a dusk to dawn light if possible.



YOu are not talking about many amps there but I would not undersize for the sake of a few dollars.

My suggestion would be google charts for wire size to length of run or just talk to the guys at the electrical supply house.  Have a good idea of what the max amps you would pull.  Like an air compressor or something that you might not keep there but would have occasion to use.


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## Jake Allen

Just suggestions. I recommend talking to a licensed electrician before committing or buying materials.

Personally, I would not go to the trouble and expense for anything less than 20 amps. 150 ft, 20 amps, you are likely looking at 6AWG copper at the smallest. (As Jimbo said, check with the wire supplier).
If you run THWN-2 in rigid conduit, it only has to be buried 6". PVC pipe with the same conductors will need to at least 18".
No conduit, I would suggest looking at UF-B, but it needs to be buried at least 24" and will need rigid conduit where it enters and exists, (at least 18" in the ground). Personally, I would no go this route.

I would also suggest the box on the dock will need to be well grounded, be an exterior and waterproof enclosure, and use a Tamper Resistant GFCI receptacle. Anything less could be dangerous.


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## 95g atl

http://www.paigewire.com/pumpWireCalc.aspx?AspxAutoDetectCookieSupport=1

Quick search and its 8 or 10 @15 amps. 
I suspect you wouldn't be approaching 15 amps so possibly can get away with thinner 12. Probably not 14. 

But like the others said. I wouldn't skimp over a few bucks. Get the thicker stuff
My humble opinion.


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## REUSSERY

When suppling power to my new dock, I ran single GFI circuit, 12/3 wire, in PVC conduit. The run is 165' long and pulls one metal hydride 150w dusk to dawn security light, two 100w halogen dock fishing lights and a single 110v covered dock outlet (for my on board batt charger). It all works great. I do suggest for additional safety, you run the wire in conduit, its only a $20 dollars for 10, 10' pipes. That's a small investment which could make all the difference, if someone were to accidentally dig up the run someday.


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## ryanh487

I thought GA building code required all buried electrical wire to be inside of conduit?  Or maybe that's just cobb county or a certain size of wire.  I know that's what I found when I was looking into adding a fuse box and outlets for the greenhouse that used to be in my back yard.


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## notnksnemor

Make sure it is GFCI protected.


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## Horns

I would not use less than a 10 gauge wire for the run


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## NE GA Pappy

Horns said:


> I would not use less than a 10 gauge wire for the run



this... at least 10 gauge.

pull it in 3/4 pvc conduit. You can push the wire through 10 ft, then glue it. Another 10ft and glue again.  

Run a gfi receptacle, and a gfi breaker back at the panel, minimum.


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## Oldstick

I wouldn't assume anything about what is going to be plugged in.  Your choice of the receptacle(s) and breaker sub panel (if used), determines the amperage of the wiring.

If you install a 20 amp rated receptacle, then make sure the wire gauge vs length is also more than adequate for 20 amps and without significant voltage drop.  Then the circuit breaker back at the main panel (or sub panel) is 20 or less.

Like others said, consult the charts or advice at the electrical place for load capacity vs length.

And actually it IS the circuit breaker chosen that should determine the rest of the circuit.  I could be wrong but I think they only make standard breakers in 15, 20 and higher.  From the description it sounds like a 15 amp breaker is more than enough.  So that would mean every other part of the circuit, (wiring and receptacle) MUST be rated 15 or higher for future safety.

I come up with 8 gauge copper for 15 amps using the calculator linked in the above post.


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## sinclair1

So I have a few questions. Can I run 6Ga to the half point in conduit where most of the load will be as far as stuff that stays on all the time(gazebo) then run the ground bury in 8-10 ga to the dock. The dock will only have a light load and will be in the off position most of the time via a switch at the half way point. The run from the half way point can be less than 40 ft if it helps. I don't have to take the long way. 

To be honest, I won't bury it 24" but it will be switched, so it's not a worry. If I sell one day I will just clip that run off since it's not to code.

The gfci I take serious, but 24" in the terrain the wire is running is not a concern.


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## oldfella1962

I've been an electronic tech for many years - I have a great respect for the hazards of electricity! What everyone else said - that's a pretty long run - not only can power drop due to energy loss, but whatever you are trying to power will have to work harder, which will wear it out faster. So better to have thicker wire (can carry more electrons) than thinner wire.


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## sinclair1

oldfella1962 said:


> I've been an electronic tech for many years - I have a great respect for the hazards of electricity! What everyone else said - that's a pretty long run - not only can power drop due to energy loss, but whatever you are trying to power will have to work harder, which will wear it out faster. So better to have thicker wire (can carry more electrons) than thinner wire.


Can I run my half way plan using 6 ga on all of it. I am 153 miles away, so I build my project bag months ahead and then just chip away at large projects. 

Next trip is finish staining a deck and make one leg of the wire project.


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## NE GA Pappy

you can run 6ga into a non fused disconnect and then come out of the disconnect with 12 gauge for 40 ft to the dock, and run smaller wire to the point of use at the gazebo too.


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## sinclair1

NE GA Pappy said:


> you can run 6ga into a non fused disconnect and then come out of the disconnect with 12 gauge for 40 ft to the dock, and run smaller wire to the point of use at the gazebo too.



Deal


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## WayneB

Voltage drop for 150 ft of 12 gauge wire is 7.14v, net will give 112 VAC, which is in the acceptable range for most appliances, and certainly enough for your anticipated use.
12 gauge wire is also adequate for a 20 amp circuit, and will allow you 4 receptacles and two lights (incandescent). LED lighting will allow more overhead, Metal Halide or halogen will allow substantially less.
Add a ground rod at about the high water line near your dock, and bond to all devices and boxes to reduce potential to ground and shock.
Per the math, a 12 gauge 4 conductor UF (alternate SOOW) (direct sunlight) from your panel, picking up the ground conductor at the ground rod, and run to your device locations should provide you serviceable amperage... However you can reduce the voltage drop by increasing wire gauge to 10 gauge.
A GFCI receptacle is not the preferred method of installation near open water, a GFCI breaker would be required. Do NOT install both, it tends to lead to premature failure or worse, failure to activate in the appropriate timeframe to prevent injury.
Your panel box will have a separate ground bus, and neutral bus;  bare copper to ground (and also to ground rod at dock), neutral (white) to neutral bus, black to breaker, and green also to ground bus.
Many 12/4 UF and SOOW will have white, black, red, green (or bare) You will use green tape to 'label' the red wire indicating it as ground at both ends for use as a secondary ground.
Should you use metallic conduit, ensure you use bushings (anti-chafing insert or cap) at each box, bond the native green or bare wire to each box and splice. Only bond the secondary ground to box and device at the receptacle box, and/or the furthest from the panel.
It may sound counter-intuitive at first glance to some; however this method increases your path to ground AND lowers the chance of a differential potential to ground, both enhancing the principal trigger to make a GFCI work correctly.


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## sinclair1

WayneB said:


> Voltage drop for 150 ft of 12 gauge wire is 7.14v, net will give 112 VAC, which is in the acceptable range for most appliances, and certainly enough for your anticipated use.
> 12 gauge wire is also adequate for a 20 amp circuit, and will allow you 4 receptacles and two lights (incandescent). LED lighting will allow more overhead, Metal Halide or halogen will allow substantially less.
> Add a ground rod at about the high water line near your dock, and bond to all devices and boxes to reduce potential to ground and shock.
> Per the math, a 12 gauge 4 conductor UF (alternate SOOW) (direct sunlight) from your panel, picking up the ground conductor at the ground rod, and run to your device locations should provide you serviceable amperage... However you can reduce the voltage drop by increasing wire gauge to 10 gauge.
> A GFCI receptacle is not the preferred method of installation near open water, a GFCI breaker would be required. Do NOT install both, it tends to lead to premature failure or worse, failure to activate in the appropriate timeframe to prevent injury.
> Your panel box will have a separate ground bus, and neutral bus;  bare copper to ground (and also to ground rod at dock), neutral (white) to neutral bus, black to breaker, and green also to ground bus.
> Many 12/4 UF and SOOW will have white, black, red, green (or bare) You will use green tape to 'label' the red wire indicating it as ground at both ends for use as a secondary ground.
> Should you use metallic conduit, ensure you use bushings (anti-chafing insert or cap) at each box, bond the native green or bare wire to each box and splice. Only bond the secondary ground to box and device at the receptacle box, and/or the furthest from the panel.
> It may sound counter-intuitive at first glance to some; however this method increases your path to ground AND lowers the chance of a differential potential to ground, both enhancing the principal trigger to make a GFCI work correctly.


I am not at the location, but I am pretty sure this crawl space circuit has a gfci breaker. Actually the box is loaded with them compared to my home here in Woodstock.
It was built in 2009, so there's no bootleg wiring to worry about either.


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## WayneB

2009 code did not enforce GFCI in crawl spaces, but most inspectors 'suggested' it strongly.
2009 construction would likely also eliminate GFCI 'no ground' which is common in older structures.
I meant to clarify; the UF wire is direct burial, and can be trenched from structure to dock, the SOOW is flexible like an extension cord, you can strap to your dock tucked under a handrail.
 Splice from one type to the other where the added ground rod splice is made using a weather proof ground or post mounted box.
If your dock articulates (floats with hinges) SOOW will not break internally as a solid conductor would, and you can leave a slight loop as strain reliefs at hinge points.


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## Jake Allen

I am confident 12 gage wire pulling an 80% load of a 20 amp service will generate way too much heat at 150 feet. That is the reason for using a larger conducter, like 6 gage copper.

I believe you are best to hire a competent electrician to do this job. There are too many risks involved, and you want things to be done right for the next person who may own your property.


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## sinclair1

Jake Allen said:


> I am confident 12 gage wire pulling an 80% load of a 20 amp service will generate way too much heat at 150 feet. That is the reason for using a larger conducter, like 6 gage copper.
> 
> I believe you are best to hire a competent electrician to do this job. There are too many risks involved, and you want things to be done right for the next person who may own your property.



I settled on 6ga to the halfway switch at gazebo and will probably do the whole thing in 6ga as the roll pricing evens the score on buying two ( cut feet ) wires.

Trust me, this will be the best job on my whole cove. Most of these folks have wire stapled to trees and wires run below the high water.

It's going in conduit to the halfway point. The only Liberty I will take is not going 24" on the ground bury, it's not an option in the terrain of the last leg. The last leg will be switched as well. 

Thanks for all the help.


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## Nitram4891

sinclair1 said:


> I settled on 6ga to the halfway switch at gazebo and will probably do the whole thing in 6ga as the roll pricing evens the score on buying two ( cut feet ) wires.
> 
> Trust me, this will be the best job on my whole cove. Most of these folks have wire stapled to trees and wires run below the high water.
> 
> It's going in conduit to the halfway point. The only Liberty I will take is not going 24" on the ground bury, it's not an option in the terrain of the last leg. The last leg will be switched as well.
> 
> Thanks for all the help.



Dont forget you are only allowed 360 of bends in one run of conduit, and you use 90 degrees going into the ground, and 90 degree coming out....so only 180 degrees left to make bends!


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## sinclair1

Nitram4891 said:


> Dont forget you are only allowed 360 of bends in one run of conduit, and you use 90 degrees going into the ground, and 90 degree coming out....so only 180 degrees left to make bends!



I am good on the section going in conduit,its a straight shot. The second leg is every man for himself.


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## sinclair1

Electrician at supplier laughed at me and said 10ga is fine


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## Oldstick

Sounds like a good plan to me.  

I was a little concerned that some seem to be suggesting to size the wire according to the anticipated load use.  That would be fine if they made standard breakers for say 5 or 10 amp circuits, but not sure that they do.

And don't forget to take pictures and/or make a sketch of the ditch, noting positions and distances from permanent structures etc.  For future reference when you need it.


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## GA native

You will not see any voltage drop in 150'.

Buy the 14/2 copper wire in the gray sheathing. And put a 15 amp breaker on it. And whatever safety outlet at the dock.

http://www.nooutage.com/vdrop.htm voltage drop calculator.


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## Jake Allen

sinclair1 said:


> Electrician at supplier laughed at me and said 10ga is fine



Maybe it will work out for you. We have used 10-2 for a 75' run on a 30 amp breaker for a camper hook-up, and had no troubles. 
It would be terrible to go to all of that trouble and have the insulation melt in the conduit though.


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## Miguel Cervantes

GA native said:


> You will not see any voltage drop in 150'.
> 
> Buy the 14/2 copper wire in the gray sheathing. And put a 15 amp breaker on it. And whatever safety outlet at the dock.
> 
> http://www.nooutage.com/vdrop.htm voltage drop calculator.



I use this calculator and "not see any voltage drop" isn't exactly an accurate statement. 

http://www.calculator.net/voltage-d...ce=150&distanceunit=feet&amperes=20&x=69&y=13

However, I am also not an electrician, so what do I know.


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## Milkman

I will offer this.   Lots of 300-400 ft chicken houses with the power panel at one end and lights and equipment at the other end.   Most of this is run with 12 guage romex type wiring.  

I have an old chicken house I use for a barn. I am powering with underground wire from a house I own.
 It is # 10/3 30 amp service to the disconnect in the chicken house.  I have lights and outlets run the full 250 ft length. I run saws, air compressor, etc. that are fully 400 ft from the panel in the house. I am certain there is voltage drop but everything works fine.


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## GA native

Miguel Cervantes said:


> I use this calculator and "not see any voltage drop" isn't exactly an accurate statement.
> 
> http://www.calculator.net/voltage-d...ce=150&distanceunit=feet&amperes=20&x=69&y=13
> 
> However, I am also not an electrician, so what do I know.



The calculator I used says 0%, at 95 degrees with 14/2 wire. 
150' is nothing, you have longer runs in your house.


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## WayneB

GA native said:


> The calculator I used says 0%, at 95 degrees with 14/2 wire.
> 150' is nothing, you have longer runs in your house.



That calculator must be defective. Loss on 12 gauge is 7 volts per my previous post.
How do you know if your wiring will provide a reasonable efficiency of operation? The National Electrical Code, 210-19(a) (FPN 4) and 215-2 (b) (FPN 3), recommends 5% voltage drop for feeder circuits and 3% for branch circuits. Let's work some examples, using the equations in the sidebar (right). Our examples use uncoated copper wire in steel conduit, for 480V branch circuits; we'll use NEC Table 9's power factor column.

Example 1: Determine voltage drop Run a No. 10 stranded wire 200 ft at 20A. Per Table 9, our "ohms to neutral per 1,000 ft" is 1.1 ohms. To complete the numerator, multiply as follows: (2 x 0.866) x 200 ft x 1.1 ohms x 20A = 7620.8 Dividing 7621 by 1000 ft gives a voltage drop of 7.7V. This drop is acceptable for our 480V circuit. A No. 12 would drop 11.8V. Boost the length to 500 ft, and that No. 10 drops 18V; the No. 12 drops 29V.

Example 2: Determine wire size Run a stranded copper wire 200 ft at 20A. You can find the wire size by algebraically altering the first equation, or you can use the following method. To complete the numerator, multiply as follows: 1.73 x 212.9 ohms x 200 ft x 20A = 89371.2 Dividing the 89371.2 by the acceptable voltage drop of 14.4V gives you 6207 circular mils. NEC Table 8 shows that a No. 12 wire satisfies the voltage drop recommendation.​http://ecmweb.com/content/basics-calculating-voltage-drop


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## CHANDLECTRIC

10-2 UF w/ grn is all you need


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## Oldstick

Thanks to some of ya'll I feel a little more competent now.  Because my gut feeling was that 150 ft. wasn't way above what many house runs are.  So I was originally thinking 12 was probably good enough for 15 amp without much risk or  10 just for good measure.  But I wasn't qualified to argue with what some of those calculator tools said.


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## chris41081

CHANDLECTRIC said:


> 10-2 UF w/ grn is all you need



This..


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## Atlanta Dawg

*I Agree...*



Horns said:


> I would not use less than a 10 gauge wire for the run



a Ten Gauge wire will work fine.  We run 15 campers and our community building from a centralized power pole and all are on 10 gauge drop cords that you can buy from Lowe's, Home Depot, etc...Some have been encased in PVC simply to protect them from being run over-several are not encased in anything.  We have had no wire failures in now 9 years.  (Except mine which I cut through while digging a slit trench to bury it-hit it with the pick axe !)

I would add:  Most of the cords run through 200 feet-even though they may need only 150 feet due to the expense of the cord-a 100 ft is not that much more than a 50 ft cord.  Most of the 200 ft runs are comprised of two 100 ft sections plugged in together).


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