I have an smallish building about 300 feet from an electrical outlet that I wish to make kinda an extension cord for so that I will have electricity to when I need to run a fan or whatever. I've thought about making an extension cord out of romex/house wire for job and using male/female extension cord plugs. My question is what size wire would I use. Or does anyone else have any ideas on how to do "on the cheap?"
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Electrical wire question
- Thread starter Mike8623
- Start date
Not enough information.
What are you planning on running?
300 feet will require a couple size increase due to length.
Number 12 wire good for 20 amps but only for say 50 cable feet.
Google "voltage drop calculator" and you will find tools to help you size the wire.
Direct bury romex can be used but being solid it does like to be rolled up.
So cord better but $$$
Cheap extension cords possible but number 10 minimum size for that distance.
Best to trench and do it right.
Budget?
Sent from my SAMSUNG-SM-G930A using Tapatalk
What are you planning on running?
300 feet will require a couple size increase due to length.
Number 12 wire good for 20 amps but only for say 50 cable feet.
Google "voltage drop calculator" and you will find tools to help you size the wire.
Direct bury romex can be used but being solid it does like to be rolled up.
So cord better but $$$
Cheap extension cords possible but number 10 minimum size for that distance.
Best to trench and do it right.
Budget?
Sent from my SAMSUNG-SM-G930A using Tapatalk
- Joined
- Jul 10, 2013
- Messages
- 1,190
This is just an idea. How about installing a solar panel and run a 12 volt fan. Might be able to do it less then a hundred bucks.
- Joined
- Jan 2, 2019
- Messages
- 6,526
If you never want to add anything else besides a fan and a radio you can cheap out and run the smallest wire you dare, those loads won't matter much and the wire is unlikely to catch anything of consequence on fire assuming you're not in the forest.
But, If you're going to the expense of running #10 wire it would be a waste IMHO to not dig a trench and bury conduit. If nothing else it will keep you from tripping on the wire going across your yard.
Solar is a definite option but doing it right will cost a fair amount and more if storage is required. Do you have any old car batteries laying around that hold a charge, if so that would make solar easier (assuming you want the exhaust fan running 24/7.
But, as things happen you will probably end up needing more power there like if you decide to do any plating or anodizing. If it was me I'd bite the bullet and trench for conduit and run an appropriate service for a sub-panel. Especially if I owned the property....
John
But, If you're going to the expense of running #10 wire it would be a waste IMHO to not dig a trench and bury conduit. If nothing else it will keep you from tripping on the wire going across your yard.
Solar is a definite option but doing it right will cost a fair amount and more if storage is required. Do you have any old car batteries laying around that hold a charge, if so that would make solar easier (assuming you want the exhaust fan running 24/7.
But, as things happen you will probably end up needing more power there like if you decide to do any plating or anodizing. If it was me I'd bite the bullet and trench for conduit and run an appropriate service for a sub-panel. Especially if I owned the property....
John
- Joined
- Feb 1, 2015
- Messages
- 9,610
Copper wire has a resistance of 1 ohm per thousand feet for 10 AWG. For every three wire gauge increase, the resistance foubles and for every three wire gauge decrease, the resistance halves. An easy rule of thumb to remember.
You have a 600 ft run, 300 out and 300 back so for 10AWG, the resistance would be .6 ohms. for a 10 ampere draw, the voltage drop would be 0 x .6 or 6 volts. If you had hypothetical 13 AWG wire the drop will be doubled to 12 volts. 12AWG will be somewhat less than that (actually, 9.5 volts)so 120 volts would be 110 volts at the far end. This would be an acceptable drop for me. !0 amps is well within the current capacity of 12 AWG wire so you're safe on that end as well.
If you ran 8AWG, the drop for a 10 ampere load would be 3.8 volts. Double the current draw and the voltage drop doubles.
- Joined
- Feb 13, 2017
- Messages
- 2,138
A lot of good answers here. Every electrical install should be considered on its' own merits, not necessarily what the "code" calls for. Actually the wire size tables in the NEC are pretty good if you take ALL the factors into consideration. I'm way out of date, well, my knowledge is, so I stand on what I remember rather than the current code. The best call I can make here is what I've done, not what a code calls for.
The first consideration is distance. Most codes call for wire size increase for each hundred feet. The next is for anticipated load. If you want a fan and light fixture now, what about in the future? The next consideration is insulation class, you don't want romex cable for open air, exposed install. If you will be burying, use UF(direct burial) or NM conduit. If aerial, use SE Triplex. If along a wall, use SER, but that isn't likely. If you opt for conduit, install SE cable.
For a 30 Amp feeder, I would recommend a minimum of Nr 6 AWG SE aluminium for the distance involved. Since you are running such a large wire, go the extra mile and make it a 220 Volt service. It won't cost that much more, might even be cheaper because of availability. And you will have it in place if(when) you ever need it. Even as simple as a second 120 volt circuit
My "barn" is actually a heavy shop building for welding, blacksmithing(?) and lumber(actually anything I don't need right away) storage. It is only a hundred feet or so from my residental service. I have a feeder of Nr 2 SER copper to the inside shop(~50ft) with a 75 Amp breaker and a feeder of Nr4 Triplex aluminium submain aerial to the barn. The barn load is nominally a few lights and a dusk to dawn flood.
But, and this is what matters, there is a buzzbox welder and a travel trailer feed, and a generator backfeed to the residence for outages. So, a 50 Amp circuit, minimum. I used what I had on hand so it may be a little large. But oversize is handy if I want to add something in the future.
Guesstimating an install remotely is difficult at best. Call it the largest wire size needed. Plus two sizes for distance. Plus another wire size if you opt for aluminium. It's a helluva lot cheaper than copper, but there is a small price to pay. You got to allow one wire size just for material. For long spans(>100ft) I usually recommend it. You're pushing the limits for a DIY project. Make sure that everything is large enough wire. And suitable sized fusing. Don't trust the NEC tables for this without allowing for distance.
.
The first consideration is distance. Most codes call for wire size increase for each hundred feet. The next is for anticipated load. If you want a fan and light fixture now, what about in the future? The next consideration is insulation class, you don't want romex cable for open air, exposed install. If you will be burying, use UF(direct burial) or NM conduit. If aerial, use SE Triplex. If along a wall, use SER, but that isn't likely. If you opt for conduit, install SE cable.
For a 30 Amp feeder, I would recommend a minimum of Nr 6 AWG SE aluminium for the distance involved. Since you are running such a large wire, go the extra mile and make it a 220 Volt service. It won't cost that much more, might even be cheaper because of availability. And you will have it in place if(when) you ever need it. Even as simple as a second 120 volt circuit
My "barn" is actually a heavy shop building for welding, blacksmithing(?) and lumber(actually anything I don't need right away) storage. It is only a hundred feet or so from my residental service. I have a feeder of Nr 2 SER copper to the inside shop(~50ft) with a 75 Amp breaker and a feeder of Nr4 Triplex aluminium submain aerial to the barn. The barn load is nominally a few lights and a dusk to dawn flood.
But, and this is what matters, there is a buzzbox welder and a travel trailer feed, and a generator backfeed to the residence for outages. So, a 50 Amp circuit, minimum. I used what I had on hand so it may be a little large. But oversize is handy if I want to add something in the future.
Guesstimating an install remotely is difficult at best. Call it the largest wire size needed. Plus two sizes for distance. Plus another wire size if you opt for aluminium. It's a helluva lot cheaper than copper, but there is a small price to pay. You got to allow one wire size just for material. For long spans(>100ft) I usually recommend it. You're pushing the limits for a DIY project. Make sure that everything is large enough wire. And suitable sized fusing. Don't trust the NEC tables for this without allowing for distance.
.
- Joined
- Feb 1, 2015
- Messages
- 9,610
Given your conditions of limited use and cheap. if it were me, I would opt for outdoor extension cords. They are not subject to code restrictions, they can be rolled up when not needed and when you need an extension for your power tools out in the back yard, you have one. Here is an offering from a regional DIY. https://www.menards.com/main/electr...ted-end/2589sw8802/p-1566282571053-c-6410.htm
You can most likely find similar offers in your location or you van order from the above.
In contrast, a proper wiring job will more than likely set you back around $1K for materials and, depending on ordinances, may require a licensed electrician. Going overhead would not be an option for me. It will require two or three poles which entails extra cost. You are well aware of the issues with burying electrical from your previous experience.
I wouldn't recommend Romex for an extension. It is solid wire and isn't meant to be flexed more than a few times. Copper work hardedns easily and if you have a break in the cable, you will most likely end up with a lot of short pieces trying to repair it. I would also suggest a dedicated outlet for your source, preferably with a suitable breaker, switched, and GFIC protection.
You can most likely find similar offers in your location or you van order from the above.
In contrast, a proper wiring job will more than likely set you back around $1K for materials and, depending on ordinances, may require a licensed electrician. Going overhead would not be an option for me. It will require two or three poles which entails extra cost. You are well aware of the issues with burying electrical from your previous experience.
I wouldn't recommend Romex for an extension. It is solid wire and isn't meant to be flexed more than a few times. Copper work hardedns easily and if you have a break in the cable, you will most likely end up with a lot of short pieces trying to repair it. I would also suggest a dedicated outlet for your source, preferably with a suitable breaker, switched, and GFIC protection.