How to wire a shed for electricity

I found myself in need to move my noisy woodworking to my back yard to avoid waking up my lady who works night shift. I decided to wire my shed and after some homework and the help of the Instructables community I started my project. Before we start I assume that you know how to wire the different fixtures.

First you will need:

• Liquid tight conduit or direct burial electrical cable
• Electrical wire (12-2)
• Switch box
• Switches, electrical outlets, light fixtures

Step 1: The right conduit

The right conduit to use is a liquidtight conduit approved for use underground or outside installations. It is a metal conduit covered by resistant plastic. You should find out if there is a code regarding buried electrical lines. My conduit will be buried between 18" and 24". You do not need to worry about frost lines because you are dealing with electricity and not pipes carrying water.
I bought 50 feet of conduit, more than the distance between my house and my shed. The conduit will be connected to a switch box in my basement and to a junction box inside my shed.
You will need an electrician's fish tape to pull the wire inside the conduit. If you find difficult to pull the wire there is a clear lubricant that you can use to make the job easier. Make sure that the lubricant dries before you connect the wire to the main box.

Comments

[dufus2506]

You should never run jacketed wire through a conduit. You should buy the spools of individual conductors, and use those.

Part of a wire's rating (how much current it can carry) is it's ability to give up heat. If you put insulated wire into a conduit, it becomes like a little oven trapping the heat that the current creates.

If you MUST use jacketed wire, you should de-rate the wire. So, a 12 gauge wire that would normally be rated for 20 amps, would instead have a 15 amp circuit breaker.

Be safe.

[irishalan]

hi i could do with your help would i be ok wiring frima double plug socket in house to shed .i got two little sheds out back joined to each other first one i want one double plug socket one switch one celling light. next i want to drill through to second shed have two double plug sockets one switch one celling light i all ready have one of the double wired in from house i can use it for chop saw light eg; i wont be uesing every thing together but need to know if one double plug from house be enough irishalan ta

[blkhawk]

Your setup should work. Make sure that the wire or extension cord that you plan to use is approved for outdoor use.

[mrbigtw]

Hello, thanks for this writeup. I'm looking to do something similar for my shed. I'm thinking 2 overhead lightbulbs with switch, a very small window like a/c unit in the summer,and small space heater in winter, and a couple other outlets for skillsaw, etc. Its about a 75 foot run, so I'm almost thinking 10 gauge, 20amp. Maybe 30 amp breaker? I'm curious about your wiring to your mainbox. Do you have this line with a new single breaker box and also a breaker in your mainbox? so a double breaker?

[blkhawk]

The small box that you see is only a switch to turn the electric off at the shed whenever I am on vacation or if I am performing an electrical upgrade in the shed. I am not an electrician and I am not sure about the power requirement for your a/c and heater. You could post a question in the Question and Answers forum to find out the breaker amperage rating needed.

[Retanotech]

what about shop vac and parachute to pull string through burried pipe or unburried pipe to then pull wire?

[blkhawk]

Have you tried it?

[evad]

I'd think about adding a ground fault interrupter type outlet...

[blkhawk]

Thank you for the suggestion. I also thought about it, since most of my woodworking is done outside the shed.

[tinker234]

excuse me could i somehow make a quick removable system for this

[blkhawk]

If you have an idea, please share with us!

[tinker234]

well i was thinking of using telescopic rods that would run from my home to the shed

[lemonie]

Useful I like it. However, I notice the NM-B cable says "INDOOR" on the pack, and is intended for normally dry conditions - you are confident that it will last in the ground?

L

[altontoth]

Although technically you shouldn't be running a multiconductor cable like that through a conduit (dissipating heat is harder for a cable in pipe), the outdoor rated cable is typically intended for direct burial (to full voltage yard lights, for example). When I did a friend's shed, we used PVC pipe ($8-10 per stick), and bought the wire (3 separate conductors, not as a cable). Also picked up a yard plug this way (put a PVC elbow into a bucket with a small post, poured concrete, planted it in the ground). Cheers

[blkhawk]

If a wire gets too hot it means that the wrong wire is used. Liquid tight conduit is approved to be used outside or buried. PVC is commonly used but I would not recommend it because it is not designed with weatherproofing in mind. If you rather use PVC, wouldn't you run with the same overheating problem like you claimed?

[2 stroke]

sorry a little late but i use the grey electrical conduit made of pvc it is made by scepter and is approved for out door use and my wire inside does not get hot it is fine but liquid tight is better and easier to install if you are wiring under ground like you did my uncle is a electrician so im sure he did a good job :P

[2 stroke]

i run indoor cable 12/3 romex through a conduit to outside my house from my garage breaker panel where i do my welding its about 12ft of a run for the cable through PVC conduit and i use a small 120 volt welder with full 20 amp draw i think you should be fine for wood working, liquid tight under ground u should be fine :P

[nagehmai]

Its technically against code to run regular indoor sheathed 12/2 Romex inside an underground conduit. The reasoning behind this is, as altontoth mentions, is due to heat dissipation issues. You can, however, run unsheathed wires inside the conduit instead. Since you're just powering a shed, you're not likely to burn anything up with what you've done though. Another, and probably cheaper alternative for anybody else looking to do this, is just to drop direct-bury NMWU Romex into your trench and forget about the conduit. This is what I used to run power to my chicken coop.

[blkhawk]

I thought about running the direct-bury cable but I thought that the wire needed some type of protection. Thank you for the suggestion.

[altontoth]

PVC is used in ground level slabs in commercial all the time. The point I'm trying to make is that you're not supposed to pull a multi-conductor line voltage cable through any sort of conduit (PVC, EMT, and liquid-tight). That's actually in both the CEC and the NEC (as far as I'm aware...at least the Canadian Electrical Code). Though to be perfectly honest, if it's just a shed, it doesn't really matter HOW it's done, as long as it's not an installation for someone else, and you're the one who's happy with it and it's safe.

[altontoth]

Hm. And of course, when I go to look up the specific rule numbers. I can't find it. I know that it was quite clearly drilled into our heads through three years of electrical training that if a line voltage multi-conductor cable is going through a raceway, it's for a limited distance only, to protect against mechanical damage. But, lacking the actual page number etc, I'll rescind my point regarding conduit.

[blkhawk]

Thank you. I thought that I was doing everything right. (Proverbs 9:8-9) "Give a reproof to a wise person and he will love you.  Give to a wise person and he will become still wiser. Impart knowledge to someone righteous and he will increase in learning"

[blkhawk]

The liquid tight conduit is weatherproof and waterproof. Its purpose is to protect the wire inside but to be on a safer side I could also use cable designed for underground or outside applications.

[lemonie]

It's down to the conduit I guess. Waterproof should do it.

L

[vincent7520]

Yes it's a real mess and it is also an example of the american contrast : the american are the only people on earth who can send men to the moon or on mars, but I never saw a domestic electric installation which was not a mess like that … 
In europe regulations are so stringent that no handyman would accept to leave an appliance in such a mess : he would be held responsible and the insurance would not cover it ! … 

how funny : same techniques vs different countries / culture => different benchmarks !…

[Hycro]

Man, I would have broke out the hammer, safety glasses, and face shield and broken the rock...but, that's just me...

[beehard44]

i would just make a huge fire pit with the rock as a centerpiece and have a BBQ party using a huge fire pit and pouring severely cold water over the rock.
Done.

[geo_caver]

I am surprise that you did not use PVC pipe as a conduit for the wires as a security against potential animal gnawing or even accidental cut off by simple root removing process or gardening.

[blkhawk]

I used liquid tight conduit but I might as well used a direct burial cable. It is against electrical codes to use a conduit with sheathed cable inside.

[NachoMahma]

.  I see two huge problems.

1. There is no ground! You need to use 12/2 with ground cable.
2. It looks like the conduit runs downhill toward your box in the first picture of step 6. This will allow water to intrude and it will flow straight to your electrical box. Move the box up a few inches. Make sure the conduit starts uphill as soon as it enters the basement to minimize water leaking in.

[blkhawk]

The wire does have ground and once the conduit goes in the shed the conduit goes up and it is connected to a junction box.

[dave566]

Im pretty sure I see a green ground screw in there for bonding the box to ground. Nice work most people ever look that.

[blkhawk]

Thank you for noticing. I became aware of the importance of correct grounding when I was studying for my A+ Certification Exam. A lack of proper grounding is not only unsafe, it is harmful for electronics like computers and other devices.

[NachoMahma]

> The wire does have ground
. Sorry about that. I think I need new glasses.

[blkhawk]

My glasses will be ready in a week. First time ever! Old age is creeping up on me.

[dhandel1]

Your land lady is fine with you running cable? are you a licensed electrician? If not, I don't think you should be giving advice to people (especially those who have never worked with cable before). I work in the real estate industry, and I know an accident waiting to happen when I seen it. IMHO call a professional when it comes to electrical and gas... is saving money really worth the very possible risk of fire?

[blkhawk]

As a matter of fact my landlady is very happy with me! Thank you very much. Some states do not require a licensed electrician to perform every single job in your house. Now if you want to be constructive and you feel that you are a qualified expert point out the danger and I will be more than willing to work on the problem but you are not going to intimidate me by saying that you work in the "real estate industry" a very vague title by the way.

[dave566]

To work on someone else's house you do need to be licensed even if it's something as simple as replacing a light. Only if you own the house can you technically do electrical work. Just use common sense and know when a project is over your head.

[blkhawk]

Indeed I own my home and the reason I feel comfortable working with electricity is that I worked with and I am also related to licensed electricians. Many homeowners do safely work with their own electrical wiring. Also many books out there explain how safely work installing things like fans, outlets, switches, etc. and they are oriented towards homeowners. I should have created a disclaimer for those brave enough to do their own work but not informed enough to do it in a safely manner. I am lucky to live in an area with building codes that are not too strict but I know that it is not the case everywhere.

[dave566]

Even though the conduit is labeled as liquid tight National Electric code recognizes that anything buried underground must use wire rated for wet locations. 12ga UF cable works OK. I like THWN wire in rigid pipe or PVC pipe. Also electrical code limits the length of flexible conduit to 6ft runs, that is from termination to termination. My best advice would be to dig up the flex, lay down 3/4" PVC conduit and fish tape 3 strands of 10ga THWN and 3 strands of 12 ga (shared ground) then you can run 120v shop stuff and you have the capability of a 240v welder circuit.