Shed wiring questions

[Paul P]

I am planning to wire my shed for outlets and lights. I plan on a dedicated circuit and the shed is about 70 feet from the panel. I am going to use 12 gage wire. So ...



If I make it a 20 amp circuit, then my understanding is need to use all 12 gage wire and 20 amp devices. Correct?



If I use 12 gage to run power out to the shed and go with a 15 amp circuit, do I need to use 12 gage running to the various devices in the shed or can I use 14?



If I use a 15 amp circuit and 12 gage wire to the devices, do the devices need to be 20 amp or 15 amp rated?



For a 15 amp circuit using either 14 gage or 12 gage can I use 20 amp devices and assume they will hold up better in the long haul?



Thanks!



Paul

 

[JD Johnson]

If I make it a 20 amp circuit, then my understanding is need to use all 12 gage wire and 20 amp devices. Correct?

Yes



If I use 12 gage to run power out to the shed and go with a 15 amp circuit, do I need to use 12 gage running to the various devices in the shed or can I use 14?

Yes but I would use 10ga to the shed and 12ga for the circuits in case I wanted to run a circular saw or other power tool I tend to overdo things though.



If I use a 15 amp circuit and 12 gage wire to the devices, do the devices need to be 20 amp or 15 amp rated?

Technically all componets are safety devices, #1 circut breaker, #2 device, #3 the wire if all the others fail.



For a 15 amp circuit using either 14 gage or 12 gage can I use 20 amp devices and assume they will hold up better in the long haul?

See above

 

[John Glover]

Just did the same thing last summer. My unlicensed, but very skilled, electrician gave me the same advice: Use 10ga wire from the panel to the shed, where I installed a circuit breaker box. From there, I used 12ga to lights and sockets. Have run power tools, two battery chargers at once, etc. with no problems. I buried the 10ga wire using the kind made for that so did not use any conduit from the panel to the shed. At the shed, I used conduit for the 12ga, but still used the wire that doesn't need it. The sides of my shed will remain open for ventilation...it's strictly for a boat.

Buy a quality box for that shed from an electrical supply store. I did, and found out they were less expensive than the cheapies at home improvement stores and better quality.

jag

 

[Bob G.]

Just keep it simple.....use a 20A circuit breaker at the panel, 12 gauge copper wire 12/2 NMB w/ground and 20A devices (outlets) in the shed. Light switches can be 15A. Are ya running conduit or using UF cable??



Bob G.

 

[Mike Simard]

Hey Paul

I am a Licsenced electrician in NH and all you need to rememder is 10 ga copper is good for 30 amps,12 ga for 20a,and 14 ga for 15 amp! If you run 10 gauge from the Main panel to a "Sub-Panel" (Small 6-8 circuit panel)you need to run 10/3 copperw/ground protected by a 2 pole 30 amp breaker in the main panel, then you must protect your branch circuits(in the shed) with breakers according to wire gauge size(12G-20a,14G-15a) and yes if you use a 20 amp breaker all the wire must be 12 gauge!



Now having said all that, The easiest way to do it (if you just want general lights and outlets)would be to run 12/2 uf(underground rated direct burial cable) from your main panel(protected by a single pole 20 a breaker) directly to the shed (to an outlet)burying the cable at least 18" then branch off and hit lights and other outlets keeping in mind to keep everything in 12 gauge (inside the shed you can switch to 12/2 rx regular indoor rated cable) and finally the 20 amp rated devices(plugs and switches) are better made and will last longer than 15 amp rated devices! Hopefully this helps and doesnt confuse you anymore:wacko:

 

[JD Johnson]

Don't forget to figure the power drop for the distance travelled in wire so you have the right size wire to provide the correct powerat the shed.

 

[Paul P]

Thanks for all the great info!



The shed is basically just for storage. Once in a great while I will run one power tool at a time and will use the circuit mostly for lighting. So far the plan is point to point:



1. 20 amp single pole breaker

2. 12/2 rx to plastic box with 20 amp GFCI outlet on inside of exterior house wall.

3. 12/2 rx through exterior wall to of house into exterior outlet with 20 amp recepticle.

4. Three 12 ga solid wires out of exterior plug into PVC conduit.

5. PVC conduit with three 12 ga solid wires goes from exterior outlet into 18 inch trench to shed and up through the shed sill into a single gange box with a 20 amp Double pole/Single Throw (DP/ST) switch so power to all devices in the shed can be switched off.

6. Branch from DP/ST switch to outlets and to switched lights using 12/2 rx and 20 amp devices.



Thanks!



Paul

 

[Paul P]

J.D.



Shed is not more than 70 feet from the panel to the first box in the shed.

 

[Barry Dufour]

Paul:

The electrical code is the minimim standards used in wiring buildings. You can always go better and in the long run you will be safer. If you can afford it, you should run a sub-panel circuit to a small sub-panel. I wouldn't go less than a 60 amp / 220 volt circuit / 6 breaker. Once the sub-panel is in then you can run the right sized wire to whatever outlet, light switch, or whatever and you will have no problems in the future. If you already having to trench then the hardest part is done. You can use direct burial wire which is the easiest. I see that you are coming from an exterior outlet from your house. With the distance and the size wire you have chosen you will get a voltage drop which will effect the breaker for the circuit in the house and will effect the tools, lights, etc. that you want to use in your shop. With the sub-panel you can safely run your equipment and have future power for whatever yo need.

Barry

 

[JD Johnson]

The electrical code is the minimim standards used in wiring buildings

Excellent point Barry, folks tend to forget that and think if it is ok'd by the city or county it must be the best but that is far from the case.

 

[Paul P]

Hi Barry



Great info. My original plan was to dedicate a new 20 amp circuit from the house panel to the shed. From reading your last reply I think you may have thought I was going to tap off of an exterior outlet but that is not the case. The shed is only 10 x 12 and is primarily for storage and will not be a workshop. Outlets are for the infrequent case that I may need to run a power tool in that area of the yard. Do you really think its necessary to go the sub-panel route with heavier gage even though its just a storage shed?



Thanks



Paul

 

[Gene B]

For your stated needs a sub panel is way beyond over kill. It makes a lot of extra work for something you don't need. People who don't do electrical work for a living seldom get it right. Just remember the exterior outlet has to have an in-use type cover ( it will have a bubble type cover on it so you can still close the lid with something plugged into it) if its in a wet location. The voltage drop for a 70 ft run should be within the 3% recommended by the code.



Gene

 

[Barry Dufour]

Paul:

I didn't realize the size of the shop. A dedicated 20 map 110 volt circuit will work. Sorry about that. I still would use direct burial wire. It's the easiet to run and will last a long time. Just make sure that any outlet that will be used ouside should be a ground fault or the breaker should be a GFI and that will protect the whole circuit. . It will protect you., also.

Barry

 

[Paul P]

So the circuit from point to point (more detail in one of my posts above) using 12 ga wire is:



1. 20 amp breaker in house panel

2. Interior GFCI outlet

3. Exterior Outlet

4. Double Pole/Single Throw switch in shed

5. branch to outlets and to lights in shed.



Gene -



What are the conditions where a bubble cover is required for an exterior outlet? Is it because it leads to downstream devices?





Barry -



I'm assuming the GFCI outlet mentioned about should do for the circuit ... right?



Thanks!



Paul

 

[Barry Dufour]

Paul: Yes the GFI should be for any outside outlet and the bubble Gene talked about was the cover for the outlet which allows you to have something plugged in and keeping it dry.

Barry

 

[Paul P]

The reason I asked about the in-use/bubble cover is that all the exterior outlets on my house do not have one. I was wondering if there are circumstances where one is required by code or if its just a good idea in general for outdoor outlets.



Paul

 

[Barry Dufour]

Paul:

Both. Years ago it wasn't required, now codes are requiring it. I still have the old ones at my house but upgrade whenever I have to replace any. You can change them all if you want to.

Barry

 

[Jeff Griffeth]

I wired my boat shed this spring and put a commercial (cheap, but not pretty) ceiling fan in. I am so glad I did. When my boat is wet, it is dry in a few hours instead of days. I just have the fan on low and it's amazing how quickly it dries with that amount of circulation compared to none before.



Jeff

 

[Paul P]

Hi



I'm hoping to complete my shed wiring project this weekend. I have the three solid 12 G wires buried in the grey PVC conduit so I need to wire up the house side and shed. I'm adding a 20 amp circuit for the storage shed which will have lighting (exterior spot lights and interior lighting and a couple of outlets (interior and exterior). At the same time I also want to add a few exterior outlets to the back of the house and a few outlets for my basement workshop. My current plan is to branch the circuit to the interior basement workshop outlets and a GFCI outlet placed in my basement workshop. From the interior GFCI outlet I would then feed the buried wire and the exterior house outlets. So ...



Is there any downside to feed both the shed outlets and shed lights from a GFCI?



Is a GFCI breaker more reliable/durable than a GFCI outlet?



Should I just go to a GFCI breaker for the entire circuit?



In general, does a buried wire require a GFCI device upstream?



In general, does exterior lighting (door lights, spot lights, etc) require a GFCI upstream?(i.e. as far as the shed part of this circuit goes, do just the exterior shed outlets require a gfci and not the interior shed outlets or lighting?)



Thanks!



Paul